The Hitchhiker’s Guide to a Red Rash in Adults

Almost every adult will experience a red rash at some time. The rash may be localized or widespread, and various factors, including infections, allergic reactions, autoimmune conditions, and systemic diseases, can cause it. In some cases, the rash may be acute, presenting suddenly in response to a trigger such as an infection or an allergy. In contrast, in others, it may be chronic, persisting for weeks, months, or even years, as seen in conditions like psoriasis and rosacea. Recognizing the underlying cause of a red rash is essential because it helps determine the appropriate management and treatment.

What is a rash?

A rash is a noticeable change in the skin’s appearance, texture, or color. It can affect a small part of the skin or cover large areas, which may look different depending on the cause. Some rashes may be dry and scaly, while others may be bumpy, swollen, or itchy.

In many rashes, the skin turns red because the blood vessels underneath it become dilated or inflamed. This can happen when the body reacts to various triggers, such as infections, allergens, or irritants. The redness is often a sign that the body’s immune system is responding to something it sees as a threat, even if it is minor or temporary. In some cases, the red may also result from increased blood flow to the area as the body tries to heal or fight off an infection.

Medical terms used to describe rashes

Before we discuss the many causes of a red rash in adults, it is helpful to define some of the key medical terms frequently used to describe rashes. Understanding these terms will help distinguish between different types of rashes and their potential causes.

• Macule: A flat, discolored spot on the skin, usually less than 1 centimeter in diameter, that does not involve any change in skin texture.
• Papule: A small, raised bump on the skin that is less than 1 centimeter in diameter and can be red, pink, or flesh-colored.
• Plaque: A raised, flat-topped area on the skin larger than 1 centimeter, often formed by the coalescence of multiple papules.
• Vesicle: A small, fluid-filled blister less than 1 centimeter in diameter, often seen in viral infections or dermatitis.
• Bulla: A larger fluid-filled blister, typically greater than 1 centimeter in diameter.
• Pustule: A small, raised bump on the skin filled with pus, often associated with infections such as acne or impetigo.
• Wheal: A raised, red, or pale area of skin that appears suddenly and is typically associated with itching, often seen in hives (urticaria).
• Erosion: A superficial break in the skin, usually resulting from the rupture of a vesicle or pustule.
• Ulcer: A deeper loss of skin, often involving both the surface and underlying layers, typically slow to heal.
• Crust: A dried-out layer of serum, blood, or pus on the surface of a lesion, commonly known as a scab.
• Scaly: Refers to rough, flaky skin that often appears due to conditions like psoriasis or eczema.
• Purpura: Red or purple spots on the skin caused by bleeding under the surface, not blanching with pressure.
• Petechiae: Tiny, pinpoint red or purple spots that result from bleeding under the skin, usually less than 3 millimeters in size.
• Lichenification: Thickening and hardening of the skin with increased visibility of skin lines, often caused by repeated scratching or rubbing.
• Excoriation: A scratch mark or superficial abrasion caused by scratching.
• Erythema: Redness of the skin due to increased blood flow, often a sign of inflammation or irritation.

What are the most common causes of red rash in adults?

Allergic contact dermatitis

Allergic contact dermatitis is an immune-mediated skin reaction caused by exposure to an allergen. The condition results from a type IV hypersensitivity reaction, where T-cells recognize the allergen and release cytokines that cause inflammation. Common allergens include nickel, latex, cosmetics, and certain medications.

• Distinguishing features: The rash typically appears as well-demarcated, red, itchy patches or blisters, often confined to the site of contact with the allergen. Chronic exposure can lead to lichenification (thickening of the skin).
• Associated symptoms: The primary symptom is itching, which can be severe. Blistering, swelling, and skin cracking may also occur. There are usually no systemic symptoms unless the reaction is widespread.
• Incidence: Allergic contact dermatitis affects individuals of all ages but is particularly common in people who frequently handle irritants. Incidence varies by geographic location and occupation.
• Management and treatment: Treatment focuses on identifying and avoiding the allergen. Topical corticosteroids are typically used to reduce inflammation and itching. In more severe cases, systemic corticosteroids may be required. Emollients can help restore the skin barrier.

Atopic dermatitis (eczema)

Atopic dermatitis is a chronic inflammatory skin condition that typically begins in childhood but can persist or develop in adulthood. It is thought to result from a combination of genetic and environmental factors that cause skin barrier dysfunction and an exaggerated immune response.

• Distinguishing features: The rash is characterized by red, scaly patches that can be intensely itchy. In chronic cases, the skin may become thickened and lichenified. The rash most commonly affects the flexural areas (e.g., behind the knees, inside the elbows).
• Associated symptoms: Itching is the hallmark symptom, often leading to scratching, which worsens the rash. Skin infections may occur due to the breakdown of the skin barrier.
• Incidence: Atopic dermatitis is common, affecting up to 20% of children and 3% of adults. The condition often runs in families and is associated with other atopic diseases, such as asthma and allergic rhinitis.
• Management and treatment: The mainstay of treatment is moisturizing the skin to prevent dryness. Topical corticosteroids or calcineurin inhibitors are used to control flare-ups. Antihistamines can help relieve itching. In severe cases, systemic immunosuppressants or biologics, such as dupilumab, may be used.

Psoriasis

Psoriasis is a chronic autoimmune condition that causes the rapid turnover of skin cells, leading to the buildup of thick, scaly plaques. The most common type is plaque psoriasis, which can affect various body parts, including the scalp, elbows, knees, and lower back.

• Distinguishing features: The rash consists of well-demarcated, raised red plaques covered with a silvery-white scale. It can vary in size and number and may be itchy or painful. Nail changes, such as pitting or onycholysis (nail detachment), are common.
• Associated symptoms: Besides the skin lesions, some patients develop psoriatic arthritis, which can cause joint pain and swelling.
• Incidence: Psoriasis affects about 2-3% of the population and typically begins in early adulthood. It is more common in individuals with a family history of the condition.
• Management and treatment: Treatment options depend on the severity of the disease. Topical treatments, such as corticosteroids and vitamin D analogs, are used for mild cases. Moderate to severe cases may require phototherapy or systemic therapies, including methotrexate, cyclosporine, or biologics targeting immune pathways.

Rosacea

Rosacea is a chronic inflammatory skin condition that primarily affects the face. It is most common in fair-skinned individuals and is often triggered by sun exposure, heat, alcohol, and spicy foods.

• Distinguishing features: The rash presents as persistent facial redness, with visible blood vessels (telangiectasias) and sometimes acne-like pustules. In some cases, patients develop rhinophyma, a thickening of the skin on the nose.
• Associated symptoms: Flushing, burning, and stinging sensations are common. Eye involvement (ocular rosacea) can cause dry, irritated eyes.
• Incidence: Rosacea affects about 5% of the population, usually between the ages of 30 and 50. It is more common in women, though men are more likely to develop rhinophyma.
• Management and treatment: Avoiding triggers is essential in managing rosacea. Topical treatments, such as metronidazole or azelaic acid, are used for mild cases. Oral antibiotics, such as doxycycline, are prescribed for moderate to severe cases. In cases of rhinophyma, laser or surgical treatments may be necessary.

Seborrheic dermatitis

Seborrheic dermatitis is a chronic inflammatory condition affecting areas of the skin rich in sebaceous glands, such as the scalp, face, and upper trunk. It is thought to be related to an abnormal immune response to the yeast Malassezia that naturally inhabits the skin.

• Distinguishing features: Seborrheic dermatitis presents as red, scaly, and flaky patches, often greasy. Dandruff is a mild form of this condition, while more severe forms may affect the face (around the nose and eyebrows), chest, and ears.
• Associated symptoms: Mild itching and irritation are common, though symptoms tend to flare and remit over time.
• Incidence: Seborrheic dermatitis affects around 5% of the population and is more common in men than women. It often peaks in infancy (as cradle cap) and again in adulthood, particularly after the age of 40. It is also more common in individuals with neurological disorders like Parkinson’s disease.
• Management and treatment: Treatment includes antifungal shampoos containing ketoconazole or selenium sulfide, and topical corticosteroids for more severe flares. Calcineurin inhibitors can be used for long-term control.

Lichen planus

Lichen planus is a chronic inflammatory condition affecting skin, mucous membranes, hair, and nails. It is thought to be autoimmune in nature, with T-cell-mediated inflammation directed at the skin.

• Distinguishing features: Lichen planus presents with flat-topped, itchy, purple or violaceous bumps, often on the wrists, lower legs, and genitalia. It can also affect the oral mucosa, appearing as white, lacy patches inside the mouth.
• Associated symptoms: Intense itching is common, and the rash may cause considerable discomfort. Oral lesions may cause burning or pain while eating.
• Incidence: Lichen planus is relatively rare, affecting around 1% of the population, most commonly between the ages of 30 and 60.
• Management and treatment: For mild cases, treatment involves topical corticosteroids, while systemic corticosteroids, retinoids, or immunosuppressants may be required for more severe cases. Oral lesions may require topical corticosteroids or other symptomatic treatments.

Herpes zoster (shingles)

Herpes zoster is caused by the varicella-zoster virus (VZV) reactivation, which remains dormant in sensory nerve ganglia after a primary varicella infection (chickenpox). When reactivated, the virus causes a painful rash in a dermatomal distribution.

• Distinguishing features: The rash consists of grouped vesicles on an erythematous base, usually limited to a single dermatome. It is often preceded by pain, itching, or tingling in the affected area.
• Associated symptoms: Pain is a key feature of shingles and may persist after the rash resolves, a condition known as postherpetic neuralgia. Systemic symptoms, such as fever and malaise, may also occur.
• Incidence: Shingles primarily affects older adults and individuals with weakened immune systems. The lifetime risk of developing shingles is about 1 in 3.
• Management and treatment: Early treatment with antiviral medications, such as acyclovir, valacyclovir, or famciclovir, can shorten the duration of the rash and reduce the risk of postherpetic neuralgia. Pain management may involve NSAIDs, gabapentin, or opioids for severe cases. Vaccination (Shingrix) is recommended for adults over 50 to prevent shingles.

Fungal infection (tinea)

Tinea refers to a group of superficial fungal infections caused by dermatophytes, which invade the keratinized tissues of the skin, hair, and nails. These infections are commonly named based on the affected body site, such as tinea corporis (body), tinea pedis (feet), and tinea capitis (scalp).

• Distinguishing features: Tinea infections often present as round, red, scaly patches with a raised, well-defined border. The center of the lesion may appear clear or less inflamed, giving it a ring-like appearance (hence the common name “ringworm”). Tinea pedis typically affects the feet, causing redness, scaling, and itching between the toes. Tinea cruris (jock itch) appears in the groin area and can be very itchy. Infections of the scalp (tinea capitis) may lead to hair loss and scaling.
• Associated symptoms: Itching is the most common symptom of tinea infections. The rash may also burn or become painful, especially if a secondary bacterial infection occurs due to scratching. Nail involvement (tinea unguium or onychomycosis) can cause thickened, discolored, and brittle nails.
• Incidence: Tinea infections are very common and affect people of all ages, though they are more prevalent in warm, humid climates and among athletes, particularly those involved in sports that require close physical contact or the use of communal locker rooms and showers.
• Management and treatment: Treatment typically involves topical antifungal agents, such as clotrimazole, terbinafine, or miconazole. Oral antifungal medications such as terbinafine or griseofulvin may be necessary for extensive or resistant infections. Good hygiene practices, such as keeping the affected area clean and dry, are essential to prevent recurrence. In cases of tinea capitis or onychomycosis, oral antifungals are usually required for effective treatment.

Symptoms commonly associated with a red rash in adults

When determining the cause of a red rash in adults, it is important to consider any associated symptoms such as fever, swollen lymph nodes, pain or burning, blisters and vesicles, joint pain, shortness of breath, fatigue, oral lesions, flu-like symptoms, and gastrointestinal symptoms. The following sections explore the causes of red rash associated with each symptom.

Red rash and fever

Red rashes that present with fever often indicate an infectious process or a systemic inflammatory disorder.

Some conditions include:

• Measles (Rubeola): Caused by the measles virus, this viral illness presents with fever, cough, coryza, conjunctivitis, and a characteristic red rash that starts on the face and spreads downward. Koplik spots (white spots in the mouth) are diagnostic. Management includes supportive care, and prevention is achieved with vaccination.
• Scarlet fever: Caused by Streptococcus pyogenes, this bacterial infection presents with fever, sore throat, and a fine red rash that feels like sandpaper, usually starting on the chest and spreading. The tongue may appear red and bumpy (“strawberry tongue”). Management includes antibiotics such as penicillin.
• Systemic lupus erythematosus (SLE): An autoimmune disease characterized by a butterfly-shaped red rash on the face along with fever, joint pain, and fatigue. Lupus rash can be differentiated by its distribution and associated systemic symptoms. Treatment involves corticosteroids and immunosuppressants.
• Rocky Mountain spotted fever: Caused by Rickettsia rickettsii, this tick-borne illness presents with fever, headache, and a red rash that starts on the wrists and ankles and spreads centrally. Early treatment with doxycycline is critical.
• Mpox (formerly monkeypox): Caused by the mpox virus, this condition typically presents with fever, headache, muscle aches, and a rash that evolves from macules to vesicles and pustules, often affecting the face, hands, and genitals. Antiviral treatment may be considered for severe cases.
• COVID-19: Caused by the SARS-CoV-2 virus, this viral infection can cause a red rash in some patients, along with fever, cough, and fatigue. Rashes may vary in appearance but can include maculopapular and urticarial lesions. Treatment focuses on supportive care and antiviral medications in severe cases.
• Toxic shock syndrome: A severe condition caused by bacterial toxins from Staphylococcus aureus or Streptococcus pyogenes, presenting with high fever, a diffuse red rash, and multi-organ failure. Immediate treatment with antibiotics and supportive care in an intensive care unit is required.
• Meningococcemia: Caused by Neisseria meningitidis, this bacterial infection leads to a petechial or purpuric rash, fever, and sepsis. Early treatment with intravenous antibiotics is essential to prevent mortality.
• Adult-onset Still’s disease: A rare inflammatory disorder presenting with recurrent fever, joint pain, and a salmon-colored bumpy rash. Diagnosis requires ruling out other causes of fever and rash. Treatment includes NSAIDs, corticosteroids, and biologic agents.
• Drug-induced exanthems: Certain medications can cause a red rash associated with fever, such as in drug reaction with eosinophilia and systemic symptoms (DRESS). Treatment involves discontinuing the offending drug and supportive care, with corticosteroids used in severe cases.

Red rash and swollen lymph nodes

Lymph nodes are small bean-shaped immune organs found throughout the body. A red rash and swollen lymph nodes are commonly seen in infectious, inflammatory, or autoimmune conditions.

Some conditions include:

• Infectious mononucleosis: Caused by the Epstein-Barr virus, it presents with swollen lymph nodes, fatigue, and a red rash, often after taking amoxicillin. Differentiating features include pharyngitis and splenomegaly. Treatment is supportive.
• HIV acute infection: During acute HIV infection, a generalized red rash may occur along with fever, swollen lymph nodes, and flu-like symptoms. Testing for HIV antibodies and RNA is crucial. Antiretroviral therapy is the cornerstone of treatment.
• Lymphoma: This cancer of the immune system can cause swollen lymph nodes and skin involvement with a red rash. It may be distinguished by persistent, painless lymphadenopathy, night sweats, and weight loss. Treatment involves chemotherapy and radiation.
• Rubella: Caused by the rubella virus, rubella presents with swollen lymph nodes and a fine red rash that starts on the face and spreads downward. Rubella is distinguished by its rapid spread and mild systemic symptoms. Vaccination is the best preventive measure.
• Cat scratch disease: Caused by Bartonella henselae, this bacterial infection leads to regional lymphadenopathy and a red papular rash at the scratch site. Serology confirms the diagnosis, and treatment involves antibiotics like azithromycin.
• Syphilis: Secondary syphilis, caused by Treponema pallidum, presents with generalized lymphadenopathy and a red rash, often on the palms and soles. Diagnosis is confirmed with serologic testing, and treatment is with penicillin.
• Tuberculosis (TB): Extrapulmonary TB can cause lymph node swelling and a red rash. Diagnosis involves TB skin testing, interferon-gamma release assays, and biopsy. Treatment involves prolonged antibiotic therapy.
• Sarcoidosis: An inflammatory disease that causes swollen lymph nodes and erythema nodosum, a red rash on the shins. Diagnosis is based on clinical findings and biopsy, with treatment focused on corticosteroids.
• Castleman disease: A rare disorder that involves lymph node enlargement and systemic symptoms, including a red rash. Diagnosis requires lymph node biopsy, and treatment may include immunotherapy or chemotherapy.
• Kikuchi-Fujimoto disease: A rare cause of swollen lymph nodes and a red skin rash, often affecting young women. Treatment is usually supportive, with nonsteroidal anti-inflammatory drugs (NSAIDs) for symptom relief.

Red rash and pain or burning

Rashes that are painful or cause burning sensations are often linked to nerve involvement, inflammation, or infection.

Some conditions include:

• Herpes zoster (shingles): Caused by the varicella-zoster virus, this condition presents with a painful, burning, or tingling sensation in a dermatomal distribution, followed by the appearance of a red, vesicular rash. Differentiating features include the unilateral, band-like distribution of the rash along a dermatome. Management includes antiviral medications like acyclovir or valacyclovir, pain relief with NSAIDs or gabapentin, and sometimes corticosteroids.
• Herpes simplex virus (HSV) infection: HSV causes painful, burning vesicles that may occur on the lips, genitals, or other skin areas. Differentiation is based on the presence of grouped vesicles on an erythematous base. Treatment includes antiviral medications like acyclovir.
• Cellulitis: A bacterial skin infection, often caused by Staphylococcus aureus or Streptococcus pyogenes, presents with a painful, warm, red rash, typically with swelling. It is distinguished by the diffuse spread of the red rash, often with systemic symptoms such as fever. Treatment involves antibiotics such as cephalexin or clindamycin.
• Erythema nodosum: A painful red rash, typically presenting as tender nodules on the shins. This condition is associated with systemic diseases such as sarcoidosis, infections, or medications. It can be distinguished by its nodular nature and distribution. Treatment often involves NSAIDs and addressing the underlying cause.
• Necrotizing fasciitis: A rapidly progressing bacterial infection, often caused by Streptococcus pyogenes, leading to severe pain, swelling, and red or purplish discoloration of the skin. It is differentiated by the rapid progression of symptoms, severe pain, and signs of systemic infection. Urgent surgical debridement and broad-spectrum antibiotics are required.
• Burns: Thermal or chemical burns cause pain and redness of the skin. They are distinguished by a history of exposure to heat, chemicals, or radiation. Management includes wound care, pain relief, and sometimes antibiotics if a secondary infection occurs.
• Erysipelas: A superficial bacterial infection of the skin, typically caused by Streptococcus pyogenes, characterized by a painful, bright red, sharply demarcated rash. It often affects the face or legs. Treatment involves antibiotics such as penicillin or clindamycin.
• Bullous pemphigoid: An autoimmune blistering disorder causing painful, red, and blistering skin, often in older adults. It is differentiated by the presence of tense blisters that do not rupture easily. Treatment involves systemic corticosteroids and immunosuppressants.
• Stevens-Johnson syndrome: A severe reaction to medications or infections, leading to painful red or purplish rashes with skin peeling. Differentiation includes mucosal involvement and systemic symptoms. Management requires hospitalization, cessation of the offending drug, and supportive care.
• Peripheral neuropathy: Conditions like diabetic neuropathy may cause burning sensations in the skin and a red rash if there is concurrent skin breakdown or infection. Treatment involves managing the underlying cause of neuropathy, such as blood sugar control in diabetes.

Red rash and blisters or vesicles

A rash associated with blisters or vesicles (fluid-filled spaces under the skin) can be seen in various infectious and inflammatory conditions.

Some conditions include:

• Varicella (chickenpox): Caused by the varicella-zoster virus, it presents with a vesicular rash, starting on the face and trunk and spreading outward. Lesions appear in various stages of development. Management includes antiviral medications in severe cases and supportive care.
• Herpes zoster (shingles): Caused by the varicella-zoster virus, this condition presents with a painful, burning, or tingling sensation in a dermatomal distribution, followed by the appearance of a red, vesicular rash. Differentiating features include the unilateral, band-like distribution of the rash along a dermatome. Management includes antiviral medications like acyclovir or valacyclovir, pain relief with NSAIDs or gabapentin, and sometimes corticosteroids.
• Herpes simplex virus (HSV) infection: HSV causes clusters of vesicles on an erythematous base, typically on the lips or genitals. The vesicles eventually rupture, leading to painful ulcerations.
• Contact dermatitis: Severe allergic contact dermatitis may cause vesicles, particularly in response to poison ivy, nickel, or latex. Avoiding the allergen and using topical corticosteroids are the mainstays of treatment.
• Impetigo: A bacterial infection caused by Staphylococcus aureus or Streptococcus pyogenes, it typically presents with honey-colored crusts that form over vesicles. It is treated with topical or oral antibiotics.
• Pemphigus vulgaris: An autoimmune blistering disorder characterized by flaccid blisters that rupture easily, leaving painful erosions. It is distinguished by the Nikolsky sign (slight rubbing of the skin causes the epidermis to separate). Treatment includes corticosteroids and immunosuppressive agents.
• Bullous pemphigoid: Characterized by tense blisters on red, inflamed skin, usually in older adults. These blisters are less likely to rupture than those in pemphigus vulgaris.
• Dyshidrotic eczema: Presents with small, itchy vesicles on the hands and feet. It is distinguished by its distribution and chronic relapsing course. Treatment involves topical steroids and moisturizers.
• Porphyria cutanea tarda: A disorder of heme metabolism, leading to fragile skin and blisters on sun-exposed areas. Treatment involves phlebotomy, hydroxychloroquine, and sun avoidance.

Red rash and joint pain

A red rash with joint pain is typically associated with inflammatory or autoimmune conditions, although some infectious conditions can also result in joint pain.

Some conditions include:

• Psoriatic arthritis: A chronic inflammatory condition that affects both the skin and joints. The rash appears as thick, red plaques with silvery scales, and joint involvement can range from mild to severe. It is distinguished by nail changes and dactylitis (sausage digits). Treatment includes NSAIDs, DMARDs, and biologics.
• Systemic lupus erythematosus (SLE): As mentioned previously, SLE can present with a butterfly-shaped red rash and joint pain. Lupus arthritis is typically non-erosive and affects multiple small joints. Treatment involves corticosteroids and immunosuppressants.
• Rheumatoid arthritis: A chronic autoimmune condition primarily affecting joints, but some patients may develop rheumatoid nodules and a red rash. It is distinguished by its symmetrical joint involvement and positive rheumatoid factor or anti-CCP antibodies. Treatment includes DMARDs and biologic agents.
• Viral arthritis (e.g., Parvovirus B19): Some viral infections, such as parvovirus B19, cause joint pain and a red rash. Parvovirus presents with a “slapped cheek” appearance in children but may cause a reticulated rash and arthritis in adults. Treatment is supportive.
• Reactive arthritis: Caused by an infection elsewhere in the body, reactive arthritis can present with a red rash and joint pain. Common triggers include gastrointestinal or genitourinary infections. Treatment involves NSAIDs and sometimes antibiotics for the underlying infection.
• Gout: An inflammatory arthritis caused by the deposition of uric acid crystals in joints, gout can cause redness and pain over affected joints, typically the big toe. Treatment includes NSAIDs, colchicine, and urate-lowering therapies.
• Erythema nodosum: As described earlier, this condition is associated with systemic inflammation and joint pain.
• Behçet’s disease: A rare inflammatory disorder causing recurrent oral ulcers, genital ulcers, and red skin lesions, often with joint pain. It is distinguished by its recurring nature and is treated with immunosuppressive agents.
• Granulomatosis with polyangiitis (formerly Wegener’s granulomatosis): A rare vasculitis that can cause skin lesions, joint pain, and systemic symptoms. It is distinguished by granulomatous inflammation on biopsy. Treatment involves immunosuppressants.
• Sjögren’s syndrome: An autoimmune condition causing dry eyes, dry mouth, and sometimes a red rash and joint pain. It is distinguished by positive anti-Ro/SSA and anti-La/SSB antibodies. Treatment is supportive, with corticosteroids and immunosuppressants used for severe cases.

Red rash and fatigue

Fatigue accompanying a red rash may suggest a systemic illness, infection, or autoimmune disorder.

Some conditions include:

• Systemic lupus erythematosus (SLE): This autoimmune disease often presents with fatigue, a red butterfly-shaped facial rash, and joint pain. Lupus is characterized by autoantibodies such as anti-dsDNA and anti-Smith antibodies. Treatment includes corticosteroids, hydroxychloroquine, and immunosuppressants.
• Infectious mononucleosis: Caused by the Epstein-Barr virus (EBV), infectious mononucleosis presents with fatigue, fever, pharyngitis, and a generalized red rash, particularly after taking antibiotics such as amoxicillin. Fatigue can persist for weeks to months. Management is supportive, with rest and hydration.
• HIV acute infection: Acute HIV infection often presents with fatigue, fever, generalized lymphadenopathy, and a nonspecific red rash. Early recognition is important, and antiretroviral therapy is the cornerstone of treatment.
• Psoriasis: A chronic autoimmune condition causing red, scaly plaques on the skin. Fatigue is common in severe cases, especially when psoriatic arthritis is present. Treatment involves topical therapies, systemic immunosuppressants, and biologics.
• Lyme disease: Caused by Borrelia burgdorferi and transmitted by ticks, Lyme disease can present with fatigue, fever, and erythema migrans, a targetoid red rash. Early diagnosis and treatment with antibiotics, such as doxycycline, are essential.
• Sarcoidosis: A multisystem inflammatory disease that can cause fatigue, pulmonary involvement, and erythema nodosum (painful red nodules on the shins). Diagnosis is based on clinical findings and biopsy, and treatment often includes corticosteroids.
• Chronic hepatitis C infection: Hepatitis C can cause a red rash, fatigue, and systemic symptoms. It is diagnosed via hepatitis C antibody and RNA tests. Treatment includes antiviral therapies such as direct-acting antivirals.
• Dermatomyositis: An autoimmune condition characterized by muscle weakness and a red rash, often accompanied by fatigue. The rash typically affects the eyelids (heliotrope rash) and knuckles (Gottron’s papules). Treatment involves corticosteroids and immunosuppressants.
• Sjӧgren’s syndrome: This autoimmune condition can cause extreme fatigue, dry eyes, dry mouth, and a red rash. Positive anti-Ro/SSA and anti-La/SSB antibodies support the diagnosis. Treatment is supportive, including systemic immunosuppression for severe cases.

Red rash and shortness of breath

When a red rash occurs alongside shortness of breath, it can indicate a severe or systemic illness.

Some conditions include:

• Sarcoidosis: Sarcoidosis often affects the lungs and skin, presenting with shortness of breath, cough, and erythema nodosum. It is diagnosed based on imaging (such as chest X-rays showing hilar lymphadenopathy) and biopsy. Treatment typically involves corticosteroids.
• Systemic lupus erythematosus (SLE): Lupus can cause pulmonary involvement, including pleuritis, pericarditis, and interstitial lung disease, alongside a characteristic red rash. Patients with pulmonary involvement may experience shortness of breath. Treatment includes immunosuppressants.
• COVID-19: SARS-CoV-2 infection may cause shortness of breath along with a red rash. The rash can vary in appearance, including maculopapular or urticarial lesions. Severe cases of COVID-19 require hospitalization, supplemental oxygen, and antiviral or anti-inflammatory treatment.
• Pulmonary vasculitis: Conditions like granulomatosis with polyangiitis (formerly Wegener’s granulomatosis) can cause red skin lesions, shortness of breath, and hemoptysis. Diagnosis is based on clinical findings, imaging, and biopsy. Treatment includes corticosteroids and immunosuppressants.
• Heart failure: In some cases, heart failure may cause redness and rashes due to venous congestion, often accompanied by shortness of breath. Echocardiography supports the diagnosis. Treatment includes diuretics, ACE inhibitors, and beta-blockers.
• Anaphylaxis: A severe allergic reaction that can cause a red rash, such as hives, along with shortness of breath, throat swelling, and wheezing. Immediate treatment with epinephrine is required.
• Disseminated herpes zoster (shingles): In rare cases, shingles can spread beyond a dermatomal distribution, causing systemic symptoms, including shortness of breath due to viral pneumonia. Antiviral therapy and supportive care are needed.
• Tuberculosis (TB): Pulmonary TB may present with shortness of breath, cough, and skin involvement, including erythema nodosum. Diagnosis is made via sputum culture and chest imaging, and treatment requires long-term antibiotics.
• Hypersensitivity pneumonitis: An allergic reaction to inhaled organic dust can cause shortness of breath and skin rashes. Diagnosis involves history and imaging, and treatment includes corticosteroids and avoidance of the offending agent.
• Vasculitis (e.g., Churg-Strauss syndrome): This condition can cause pulmonary involvement with shortness of breath and skin manifestations, including a red rash. Treatment involves corticosteroids and immunosuppressants.

Red rash and oral lesions

When oral lesions accompany red rashes, the cause is often systemic or immunologic.

Some conditions include:

• Hand, foot, and mouth disease: Caused by the coxsackievirus, this viral infection presents with a red rash on the hands, feet, and oral lesions such as ulcers. Management is supportive.
• Pemphigus vulgaris: An autoimmune blistering disorder that affects both the skin and mucous membranes, causing painful oral ulcers and fragile blisters. Diagnosis is confirmed by biopsy, and treatment involves high-dose corticosteroids and immunosuppressants.
• Oral lichen planus: An inflammatory condition that causes white, lacy patches in the mouth and can also present with a red, itchy skin rash. Treatment includes topical corticosteroids and oral hygiene measures.
• Herpes simplex virus (HSV) infection: HSV can cause painful vesicles on the lips, tongue, and inside the mouth, along with a red skin rash. Antiviral medications such as acyclovir are the primary treatment.
• Aphthous stomatitis: Commonly known as canker sores, this condition presents with painful oral ulcers and may be associated with a red rash in certain systemic diseases. Treatment is symptomatic, including topical corticosteroids.
• Syphilis: Secondary syphilis can present with mucosal lesions in the mouth (mucous patches) along with a generalized red rash. Treatment with penicillin is curative.
• Systemic lupus erythematosus (SLE): Lupus can cause painless oral ulcers along with a red facial rash and systemic symptoms. Treatment includes corticosteroids and immunosuppressants.
• Stevens-Johnson syndrome (SJS): A severe reaction to medications or infections, characterized by painful red or purplish skin lesions and mucosal involvement, including oral ulcers. Treatment requires hospitalization, cessation of the offending drug, and supportive care.
• Behçet’s disease: This inflammatory condition causes recurrent painful oral ulcers, genital ulcers, and skin lesions. It is differentiated by the presence of recurrent ulcers and systemic involvement. Treatment involves corticosteroids and immunosuppressants.
• Erythema multiforme: Often triggered by infections such as herpes simplex, erythema multiforme presents with targetoid red lesions and mucosal involvement, including oral ulcers. Management involves supportive care and, in severe cases, corticosteroids or antivirals.

Red rash and flu-like symptoms

Flulike symptoms such as fever, muscle aches, and fatigue, combined with a red rash, often suggest an infectious cause.

Some conditions include:

• COVID-19: As previously mentioned, COVID-19 can cause flu-like symptoms with a red rash that may be maculopapular or urticarial. Management includes supportive care, antiviral medications, and, in severe cases, hospitalization.
• Viral exanthems: Viral illnesses such as measles, rubella, and roseola can cause flu-like symptoms followed by a red rash. Measles presents with fever, cough, conjunctivitis, and a red rash. Rubella causes a milder illness with a fine red rash. Roseola presents with a high fever followed by a sudden red rash as the fever subsides. Management is supportive.
• Mpox (formerly monkeypox): Mpox, caused by the mpox virus, presents with flu-like symptoms such as fever and body aches, followed by a red rash that evolves into vesicles and pustules. Antiviral therapy may be used in severe cases.
• Parvovirus B19 infection: Known for causing erythema infectiosum (fifth disease), parvovirus B19 can cause flulike symptoms with a red “slapped cheek” rash in children and a reticulated rash in adults. Treatment is supportive.
• Systemic lupus erythematosus (SLE): As previously described, lupus can present with flulike symptoms, joint pain, and a red facial rash. Treatment includes corticosteroids and immunosuppressants.
• Rocky Mountain spotted fever: This tick-borne illness, caused by Rickettsia rickettsii, presents with flulike symptoms followed by a red rash that typically begins on the wrists and ankles. Early treatment with doxycycline is crucial.
• Toxic shock syndrome: Caused by bacterial toxins, toxic shock syndrome presents with flulike symptoms, high fever, hypotension, and a red, diffuse rash. Treatment includes antibiotics and intensive supportive care.
• Disseminated herpes zoster (shingles): Shingles can cause systemic symptoms with flu-like symptoms, particularly in immunocompromised individuals. Antiviral therapy is essential.
• Acute HIV infection: Acute HIV infection can cause flulike symptoms along with a generalized red rash. Early diagnosis and initiation of antiretroviral therapy are crucial.

Red rash and gastrointestinal symptoms

Gastrointestinal symptoms such as nausea, vomiting, or diarrhea, combined with a red rash, often suggest a systemic infection or inflammatory disorder.

Some conditions include:

• Viral gastroenteritis with a secondary skin reaction: Gastrointestinal infections, such as those caused by norovirus or rotavirus, may occasionally cause a secondary skin reaction in the form of a red rash. Treatment is supportive, including hydration.
• Kawasaki disease: This vasculitis primarily affects children and presents with fever, gastrointestinal symptoms, and a red rash on the trunk and extremities. It can cause coronary artery aneurysms if untreated. Treatment includes IV immunoglobulin and aspirin.
• Systemic lupus erythematosus (SLE): Lupus can cause abdominal pain and other gastrointestinal symptoms, often in conjunction with a red facial rash. Diagnosis involves antibody testing, and treatment includes corticosteroids and immunosuppressants.
• Celiac disease: An autoimmune disorder triggered by gluten ingestion, celiac disease can cause gastrointestinal symptoms such as diarrhea and malabsorption, along with dermatitis herpetiformis, a red, blistering rash. Treatment involves a gluten-free diet.
• Henoch-Schönlein purpura (HSP): A small-vessel vasculitis that primarily affects children but can also occur in adults. HSP presents with abdominal pain, gastrointestinal bleeding, and a purpuric red rash, typically on the lower extremities. Treatment is supportive, but corticosteroids may be required for severe cases.
• Typhoid fever: Caused by Salmonella typhi, this bacterial infection can cause gastrointestinal symptoms such as abdominal pain, nausea, and diarrhea, along with a red or rose-colored rash. Treatment involves antibiotics such as ceftriaxone or azithromycin.
• Inflammatory bowel disease (IBD): Conditions such as Crohn’s disease and ulcerative colitis may present with gastrointestinal symptoms and extraintestinal manifestations such as erythema nodosum or pyoderma gangrenosum, both of which cause red rashes. Treatment includes immunosuppressants and biologics.
• Toxic shock syndrome: As previously mentioned, toxic shock syndrome can cause vomiting and diarrhea, along with a red rash. Immediate treatment with antibiotics and supportive care is essential.
• Drug reaction with eosinophilia and systemic symptoms (DRESS): This severe drug reaction can cause gastrointestinal symptoms, such as liver involvement and a red rash. Treatment involves discontinuing the offending drug and systemic corticosteroids.
• Whipple’s disease: A rare bacterial infection caused by Tropheryma whipplei. Whipple’s disease can cause chronic diarrhea, weight loss, and a red rash. Diagnosis is confirmed by small bowel biopsy, and treatment requires long-term antibiotics.

Advice for patients

Patients with red rash should seek medical attention if the rash is persistent, widespread, painful, or associated with other concerning symptoms such as fever, difficulty breathing, or mucosal involvement. Treatment depends on the underlying cause. For mild allergic rashes, over-the-counter antihistamines and topical corticosteroids may be sufficient. However, conditions such as vasculitis, severe drug reactions, or infections like meningococcemia require urgent medical attention and specific treatments such as corticosteroids, antibiotics, or hospitalization. If the rash is spreading rapidly, painful, or accompanied by systemic symptoms like high fever, confusion, or difficulty breathing, the patient should seek emergency care.

Answers to commonly asked questions about red rashes in adults

Is my rash contagious?

Not all rashes are contagious, but some are. Rashes caused by infections like chickenpox, shingles, or ringworm can spread to other people, primarily through direct contact. Other rashes, like those from allergies, eczema, or psoriasis, are not contagious and cannot be passed from one person to another. Your doctor can help you figure out whether your rash could be contagious.

Should I be worried about my rash?

Most rashes are not serious and will go away with some simple treatments, like moisturizing creams or antihistamines. However, you should see a doctor if your rash is painful, spreading quickly, accompanied by a fever, or if you have any other symptoms like difficulty breathing, swelling, or a sore throat. Rashes that last for a long time or keep coming back might need special attention.

How long will my rash last?

The duration of a rash depends on what’s causing it. Some rashes, like those from mild allergies, may go away in a few days, especially if you avoid the trigger. Others, like eczema or psoriasis, can last a long time and may come and go. If your rash is from an infection, it usually clears up once the infection is treated. Your doctor can give you a better idea based on what’s causing your rash.

What can I do to treat my rash at home?

You can try simple home treatments for many rashes like keeping the skin clean and dry, avoiding scratching, and using a gentle moisturizer to soothe irritation. Over-the-counter creams like hydrocortisone or antihistamines may help with itching. If you think your rash is caused by an allergy, try to avoid the thing that might have triggered it. However, if your rash worsens or doesn’t improve with home care, it’s a good idea to see your doctor.

Summary

A red rash in adults is a common symptom associated with many conditions. Identifying the cause requires careful attention to associated symptoms such as fever, swollen lymph nodes, or itching, as well as a thorough medical history and physical examination. Allergic contact dermatitis is a common cause, but infections, autoimmune diseases, and drug reactions are also frequent culprits. Proper diagnosis and timely treatment are essential, as some conditions may be life-threatening or require urgent medical intervention.