A rash is a change in the color, texture, or appearance of the skin. Rashes may be caused by irritation, allergies, infections, medications, autoimmune conditions, heat, sunlight, or other conditions.

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Contact Dermatitis
 

Contact dermatitis occurs when the skin reacts to an irritant or allergen.

Common triggers include:
 

• Poison ivy, poison oak, and poison sumac

• Soaps and detergents

• Fragrances and cosmetics

• Nickel and other metals

• Adhesives

• Cleaning products

• Certain topical medications

The rash is usually red and itchy and primarily affects areas that contacted the trigger. Blisters may occur.
 

Treatment involves avoiding the trigger and may include moisturizers or topical corticosteroids.

Hives (Urticaria)
 

Hives (urticaria) are raised, itchy welts caused by activation of mast cells in the skin. They may occur from allergic or non-allergic immune reactions, infections, medications, physical triggers, autoimmune mechanisms, or for no identifiable reason. are raised, itchy welts that may move or change location. Individual hives usually disappear within 24 hours, although new ones may continue to develop. Antihistamines are commonly used for uncomplicated hives.
 

Fungal and Bacterial Rashes
 

Ringworm (Tinea Corporis)

Ringworm is a fungal infection, not a worm.

It typically causes:
 

• Circular or ring-shaped lesions

• A scaly, raised border

• Central clearing

• Itching

Treatment usually involves antifungal medication.

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Candida
 

Candida is a yeast that commonly causes rashes in warm, moist areas such as:
 

• Groin

• Under the breasts

• Abdominal folds

• Diaper area
   

The rash is often bright red with smaller satellite bumps or pustules around the main rash.
 

Tinea Versicolor
 

Tinea versicolor, also called pityriasis versicolor, is caused by an overgrowth of Malassezia, a yeast that normally lives on the skin. It is not caused by poor hygiene and is generally not contagious.
 

It commonly affects the:
 

• Chest

• Back

• Shoulders

• Upper arms

• Neck

The patches may be:
 

• Lighter or darker than surrounding skin

• White, tan, pink, brown, or reddish

• Slightly scaly

• Mildly itchy or asymptomatic

The discoloration may become more noticeable after tanning because affected areas may not tan normally. Treatment may include ketoconazole, selenium sulfide, or other antifungal medications. Skin color may take weeks to months to return to normal after successful treatment. Recurrence is common.

Impetigo
 

Impetigo is a contagious bacterial skin infection, especially common in children.

It commonly causes sores or blisters that rupture and develop honey-colored crusts.

Antibiotic treatment is usually recommended.

Cellulitis
 

Cellulitis is a bacterial infection of deeper layers of the skin.
 

Symptoms may include:

• Expanding redness

• Warmth

• Swelling

• Pain or tenderness

• Fever or chills
   

Cellulitis requires medical evaluation and is generally treated with antibiotics.

Inflammatory Rashes
 

Perioral Dermatitis
 

Perioral dermatitis causes small inflammatory bumps around the mouth, nose, or eyes.

Symptoms may include:
 

• Small red or skin-colored papules

• Occasional pustules

• Dry or flaky skin

• Burning, stinging, or itching

The rash around the mouth often spares a narrow strip immediately surrounding the lips.

Unlike acne, blackheads and whiteheads are generally absent.
 

Triggers may include:

• Topical corticosteroids

• Facial cosmetics or skin products

• Heavy or occlusive creams

• Inhaled or nasal corticosteroids contacting the skin
   

Topical corticosteroids may temporarily improve the rash but can ultimately worsen or perpetuate it. A temporary flare may occur when steroids are discontinued.

Treatment may include gentle skin care, topical metronidazole or other medications, and oral doxycycline or another appropriate antibiotic for more persistent disease.

Rosacea
 

Rosacea is a chronic inflammatory condition affecting the central face.

Symptoms may include:
 

• Persistent facial redness

• Flushing

• Visible small blood vessels

• Red papules or pustules

• Burning or stinging

• Sensitive skin
   

Unlike acne, comedones are generally absent.
 

Common triggers include:
 

• Sun exposure

• Heat or cold

• Hot beverages

• Spicy foods

• Alcohol

• Exercise

• Emotional stress

• Certain skin products

Treatment depends on the symptoms and may include:
 

• Metronidazole

• Azelaic acid

• Doxycycline

• Brimonidine or oxymetazoline for persistent redness

• Laser or light treatment for visible blood vessels
   

Ocular Rosacea

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• Red or irritated eyes

• Burning or gritty sensation

• Dry or watery eyes

• Eyelid inflammation

• Recurrent styes
   

Eye pain, significant light sensitivity, or vision changes require prompt evaluation.

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Atopic Dermatitis (Eczema)
 

Eczema is a chronic inflammatory condition that commonly causes:
 

• Dry skin

• Itching

• Redness

• Scaling or cracking

• Thickened skin with chronic scratching

Treatment focuses on regular moisturization, avoiding triggers, and controlling inflammation with topical corticosteroids or other medications when needed.

Granuloma Annulare
 

Granuloma annulare is a usually harmless inflammatory condition that produces raised rings or arcs.
 

It commonly affects the:

• Hands

• Fingers

• Feet

• Ankles

• Elbows
   

Lesions are usually:

• Smooth

• Firm

• Skin-colored, pink, red, or purple

• Minimally itchy or asymptomatic

• Not scaly

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Granuloma annulare often disappears without treatment, although this may take months or years. Persistent lesions may be treated with topical or injected corticosteroids or other dermatologic treatments.

Pityriasis Alba

A mild inflammatory skin condition seen mostly in children and adolescents. It causes poorly defined, mildly scaly patches that eventually become lighter than the surrounding skin, commonly on the face, upper arms, and shoulders. It is associated with dry skin and atopic dermatitis and often becomes more noticeable after sun exposure because the surrounding skin tans. Treatment is usually moisturizers, sunscreen, and sometimes a mild topical corticosteroid. Normal pigmentation gradually returns, although it may take months.

Other Rashes

Melasma 

A benign condition causing symmetric brown or gray-brown patches, usually on the face. It is associated with sun exposure and hormonal changes, particularly pregnancy and estrogen/progestin-containing medications. Hormone-related melasma may fade after pregnancy or after the hormonal trigger is removed, but it can persist or recur. Sun protection is important because sunlight can worsen or reactivate the pigmentation. Treatment begins with daily sun protection. Prescription treatments such as hydroquinone, tretinoin, azelaic acid, or combination therapy may be used when needed.
 

Non-Blanching Rashes
 

Petechiae and purpura generally do not disappear when pressed.

They may result from many conditions, including infections, platelet disorders, blood-vessel inflammation, medications, or other causes. A new unexplained non-blanching rash accompanied by fever or significant illness requires prompt medical evaluation.
 

Heat Rash
 

Heat rash occurs when sweat becomes trapped within the skin.

It commonly causes clusters of tiny red or clear bumps on the:
 

• Neck

• Chest

• Back

• Skin folds

• Areas under tight clothing

Cooling the skin and avoiding excessive heat usually helps.
 

Sunlight Rashes
 

Polymorphous Light Eruption (PMLE)
 

PMLE is a relatively common reaction to ultraviolet light, often occurring during spring, early summer, or after sudden intense sun exposure.

It may cause:

• Itchy red bumps

• Plaques

• Small blisters

• Other itchy patches
   

Common locations include the chest, shoulders, arms, neck, and legs.

The rash usually appears hours to several days after sun exposure and improves after avoiding further exposure. PMLE may become less severe as the skin gradually becomes accustomed to sunlight during the season.

Solar Urticaria
 

Solar urticaria is a rare form of hives triggered by sunlight or certain wavelengths of light. Unlike PMLE, symptoms usually develop within minutes of exposure.

Symptoms include:
 

• Raised itchy hives

• Redness

• Burning or stinging

• Swelling

The rash usually improves relatively quickly after leaving the light.

Extensive reactions can rarely cause systemic symptoms. Difficulty breathing, throat swelling, fainting, or signs of anaphylaxis require emergency treatment.
 

Autoimmune Rashes
 

Cutaneous Lupus

Lupus is an autoimmune disease that can affect the skin and other organs. Several different rashes may occur with lupus. A rash alone does not mean that someone has systemic lupus.
 

-Malar ("Butterfly") Rash

A malar rash typically:
 

• Crosses the cheeks and bridge of the nose

• Forms a butterfly-shaped pattern

• May worsen after sun exposure

• Classically spares the nasolabial folds

-Discoid Lupus
 

• Round or disc-shaped inflammatory plaques

• Scaling

• Pigment changes

• Scarring

• Permanent hair loss when the scalp is involved

Subacute Cutaneous Lupus
 

This form commonly produces a photosensitive rash consisting of:

• Red, scaly patches

• Ring-shaped lesions

• Lesions on the chest, back, shoulders, or arms
   

Other Symptoms Suggesting Systemic Lupus

• Joint pain or swelling

• Unexplained fever

• Mouth or nasal ulcers

• Unexplained hair loss

• Raynaud phenomenon

• Chest pain with deep breathing

• Blood-count abnormalities

• Blood or protein in the urine

Psoriasis
 

Psoriasis is a chronic immune-mediated inflammatory skin condition that causes skin cells to build up more quickly than normal.
 

The most common form, plaque psoriasis, causes:
 

• Well-defined red or pink plaques

• Silvery-white scale

• Itching, burning, or soreness

• Cracking or bleeding in more severe areas

Common locations include:
 

• Scalp

• Elbows

• Knees

• Lower back

• Buttocks

• Around or behind the ears
   

Other Types of Psoriasis
 

Guttate psoriasis - Causes many small, drop-like scaly spots, often on the trunk and extremities. It may appear after an infection such as streptococcal pharyngitis, especially in children and young adults.

Inverse psoriasis - Causes smooth, red, inflamed patches in skin folds such as the groin, armpits, under breasts, and between the buttocks​. It often has little or no scale because of moisture in these areas.

Pustular psoriasis - Causes sterile, pus-filled bumps surrounded by inflamed skin. Localized forms can affect the palms and soles, while generalized pustular psoriasis can be severe and may require urgent medical care.

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Some people with psoriasis develop psoriatic arthritis. Persistent joint symptoms in someone with psoriasis should be evaluated because early treatment can help prevent permanent joint damage. Symptoms include:
 

• Joint pain

• Joint swelling

• Morning stiffness

• Swelling of an entire finger or toe

• Heel or tendon pain

• Nail changes

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Psoriasis may flare with:
 

• Infections

• Skin injury

• Stress

• Smoking

• Heavy alcohol use

• Certain medications

• Cold, dry weather
   

Treatment
 

• Moisturizers

• Topical corticosteroids

• Vitamin D–related topical medications

• Other prescription topical treatments

• Phototherapy

• Oral systemic medications

• Injectable or infused biologic medications
   

Viral Rashes
 

A viral exanthem is a widespread rash caused by a viral infection. These are especially common in children.

Roseola
 

1. Several days of high fever

2. Sudden improvement in the fever

3. A pink rash beginning on the trunk and spreading outward

Fifth Disease (parvovirus B19)
 

• Bright red "slapped-cheek" facial redness

• A lacy rash on the arms, legs, or trunk

Parvovirus B19 exposure is particularly important during pregnancy and in people with certain blood disorders or weakened immune systems.

Hand, Foot, and Mouth Disease
 

• Fever

• Painful mouth sores

• Spots or blisters on the palms and soles

• Rash on the buttocks, legs, arms, or other areas

Chickenpox
 

• Intensely itchy lesions

• Red bumps that develop into blisters and crusts

• Lesions begin on the trunk, face, or scalp and spread to the extremities

• Red bumps that develop into blisters and crusts

• usually spares palms and soles

• Lesions in different stages of development at the same time

Measles
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• A rash beginning around the face or hairline and spreading downward

• The rash is usually preceded by high fever, cough, runny nose (coryza), and red/watery eyes (conjunctivitis).

• Koplik spots—tiny white or bluish-white spots on the inside of the cheeks—may appear before the skin rash.

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Rubella
 

• Mild fever

• Swollen lymph nodes

• Pink rash beginning on the face and spreading to the body
   

Rubella infection during pregnancy can cause severe fetal complications.

Pityriasis Rosea 

A self-limited inflammatory rash that often follows a viral infection. It begins with a single larger “herald patch,” followed days to weeks later by multiple smaller oval, scaly patches, primarily on the trunk and proximal extremities. The lesions usually follow skin tension lines on the back, producing a “Christmas-tree” pattern. It usually resolves on its own within about 6–8 weeks, although it can last longer. Treatment is generally aimed at itching with topical corticosteroids.

Drug Rashes
 

Medication Exanthems
 

A medication exanthem, or morbilliform drug eruption, commonly produces widespread pink or red flat spots and small raised bumps.
 

The rash often:

• Begins on the trunk

• Spreads symmetrically

• Consists of macules and papules

• Itches

• Blanches with pressure

It commonly develops days to a few weeks after starting a medication, although timing varies.
 

Common triggers include certain:
 

• Antibiotics

• Antiseizure medications

• Allopurinol

• Anti-inflammatory medications

A rash developing while taking a medication does not automatically mean the person is allergic to that medication. Viral infections can produce similar rashes and can sometimes interact with medications to increase the likelihood of an eruption.

 

Signs of a Serious Drug Reaction
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Seek urgent or emergency evaluation for a medication-associated rash with:
 

• Blistering or peeling skin

• Significant skin pain

• Mouth, eye, or genital sores

• Facial swelling

• Difficulty breathing

• High fever or severe illness

• Purple or non-blanching lesions

• Signs of internal-organ involvement
   

Serious reactions include Stevens-Johnson syndrome/toxic epidermal necrolysis (SJS/TEN), DRESS, and anaphylaxis.

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