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Definition

Rashes involve changes in the color, feeling or texture of your skin.

Alternative Names

Skin redness or inflammation; Skin lesion; Rubor; Skin rash; Erythema

Considerations

Often, the cause of a rash can be determined from how it looks and its symptoms. Skin testing, such as a biopsy, may also be used to help with diagnosis. Other times, the cause of the rash remains unknown.

Causes

A simple rash is called dermatitis, meaning inflammation of the skin. Contact dermatitis is caused by things your skin touches, such as:

  • Chemicals in elastic, latex, and rubber products
  • Cosmetics, soaps, and detergents
  • Dyes and other chemicals in clothing
  • Poison ivy, oak, or sumac
Poison oak rash on the arm
Poison oak rash on the arm. Several plants produce toxins that cause skin reaction. This is the appearance of poison oak dermatitis. Note the typical linear streaks produced either by scratching or brushing against the plant. (Image courtesy of the Centers for Disease Control and Prevention.)

Seborrheic dermatitis is a rash that appears in patches of redness and scaling around the eyebrows, eyelids, mouth, nose, trunk, and behind the ears. If it happens on your scalp, it is called dandruff in adults and cradle cap in infants.

Age, stress, fatigue, weather extremes, oily skin, infrequent shampooing, and alcohol-based lotions aggravate this harmless but bothersome condition.

Other common causes of a rash include:

  • Eczema (atopic dermatitis) -- Tends to happen in people with allergies or asthma. The rash is generally red, itchy, and scaly.
  • Psoriasis -- Tends to occur as red, scaly, patches over joints and along the scalp. It is sometimes itchy. Fingernails may also be affected.
  • Impetigo -- Common in children, this infection is from bacteria that live in the top layers of the skin. It appears as red sores that turn into blisters, ooze, then for a honey colored crust over.
  • Shingles -- A painful blistered skin condition caused by the same virus as chickenpox. The virus can lie dormant in your body for many years and re-emerge as shingles. It usually affects only one side of the body.
  • Childhood illnesses such as chickenpox, measles, roseola, rubella, hand-foot-mouth disease, fifth disease, and scarlet fever.
  • Medicines and insect bites or stings.

Many medical conditions can cause a rash as well. These include:

  • Lupus erythematosus (an immune system disease)
  • Rheumatoid arthritis, especially the juvenile type
  • Kawasaki disease (inflammation of the blood vessels)
  • Certain body-wide (systemic) viral, bacterial or fungal infections

Home Care

Most simple rashes will improve with gentle skin care and by avoiding irritating substances. Follow these general guidelines:

  • Avoid scrubbing your skin.
  • Use gentle cleansers
  • Avoid applying cosmetic lotions or ointments directly on the rash.
  • Use warm (not hot) water for cleaning. Pat dry, don't rub.
  • Stop using any recently added cosmetics or lotions.
  • Leave the affected area exposed to the air as much as possible.
  • Try calamine medicated lotion for poison ivy, oak, or sumac, as well as for other types of contact dermatitis.

Hydrocortisone cream (1%) is available without a prescription and may soothe many rashes. Stronger cortisone creams are available with a prescription. If you have eczema, apply moisturizers over your skin. Try oatmeal bath products, available at drugstores, to relieve symptoms of eczema or psoriasis. Oral antihistamines may help relieve itchy skin.

When to Contact a Medical Professional

Call 911 or the local emergency number if:

  • You are short of breath, your throat is tight, or your face is swollen
  • Your child has a purple rash that looks like a bruise

Call your health care provider if:

  • You have joint pain, fever, or a sore throat
  • You have streaks of redness, swelling, or very tender areas as these may indicate an infection
  • You are taking a new medicine -- DO NOT change or stop any of your medicines without talking to your provider
  • You may have a tick bite
  • Home treatment doesn't work, or your symptoms get worse

What to Expect at Your Office Visit

Your provider will perform a physical examination and ask about your medical history and symptoms. Questions may include:

  • When did the rash begin?
  • What parts of your body are affected?
  • Does anything make the rash better? Worse?
  • Have you used any new soaps, detergents, lotions, or cosmetics recently?
  • Have you been in any wooded areas recently?
  • Have you noticed a tick or insect bite?
  • Have you had any change in your medicines?
  • Have you eaten anything unusual?
  • Do you have any other symptoms, like itching or scaling?
  • What medical problems do you have, such as asthma or allergies?
  • Have you recently traveled out of the area where you live?

Tests may include:

Depending on the cause of your rash, treatments may include medicated creams or lotions, medicines taken by mouth, or skin surgery.

Many primary care providers are comfortable dealing with common rashes. For more complicated skin disorders, you may need a referral to a dermatologist.

Gallery

Poison oak rash on the arm
Poison oak rash on the arm. Several plants produce toxins that cause skin reaction. This is the appearance of poison oak dermatitis. Note the typical linear streaks produced either by scratching or brushing against the plant. (Image courtesy of the Centers for Disease Control and Prevention.)
Poison oak rash on the arm
Poison oak rash on the arm. Several plants produce toxins that cause skin reaction. This is the appearance of poison oak dermatitis. Note the typical linear streaks produced either by scratching or brushing against the plant. (Image courtesy of the Centers for Disease Control and Prevention.)
Erythema toxicum on the foot
Newborn infants may have Erythema toxicum, a rash that is characterized by patchy redness with central vesicles. The rash is temporary, and the location may move (transient). (Image courtesy of the Centers for Disease Control and Prevention.)
Poison oak rash on the arm
Poison oak rash on the arm. Several plants produce toxins that cause skin reaction. This is the appearance of poison oak dermatitis. Note the typical linear streaks produced either by scratching or brushing against the plant. (Image courtesy of the Centers for Disease Control and Prevention.)
Poison oak rash on the arm
Poison oak rash on the arm. Several plants produce toxins that cause skin reaction. This is the appearance of poison oak dermatitis. Note the typical linear streaks produced either by scratching or brushing against the plant. (Image courtesy of the Centers for Disease Control and Prevention.)
Poison oak rash on the arm
Poison oak rash on the arm. Several plants produce toxins that cause skin reaction. This is the appearance of poison oak dermatitis. Note the typical linear streaks produced either by scratching or brushing against the plant. (Image courtesy of the Centers for Disease Control and Prevention.)
Poison oak rash on the arm
Poison oak rash on the arm. Several plants produce toxins that cause skin reaction. This is the appearance of poison oak dermatitis. Note the typical linear streaks produced either by scratching or brushing against the plant. (Image courtesy of the Centers for Disease Control and Prevention.)
Poison oak rash on the arm
Poison oak rash on the arm. Several plants produce toxins that cause skin reaction. This is the appearance of poison oak dermatitis. Note the typical linear streaks produced either by scratching or brushing against the plant. (Image courtesy of the Centers for Disease Control and Prevention.)
Poison oak rash on the arm
Poison oak rash on the arm. Several plants produce toxins that cause skin reaction. This is the appearance of poison oak dermatitis. Note the typical linear streaks produced either by scratching or brushing against the plant. (Image courtesy of the Centers for Disease Control and Prevention.)
Poison oak rash on the arm
Poison oak rash on the arm. Several plants produce toxins that cause skin reaction. This is the appearance of poison oak dermatitis. Note the typical linear streaks produced either by scratching or brushing against the plant. (Image courtesy of the Centers for Disease Control and Prevention.)
Poison oak rash on the arm
Poison oak rash on the arm. Several plants produce toxins that cause skin reaction. This is the appearance of poison oak dermatitis. Note the typical linear streaks produced either by scratching or brushing against the plant. (Image courtesy of the Centers for Disease Control and Prevention.)
Bullous pemphigoid - close-up of tense blisters
Pemphigus is classified as one of the blistering diseases. These is a close-up picture of typical lesions. Very small blisters are called vesicles. Larger blisters, like these, are called bullae.
Bullous pemphigoid - close-up of tense blisters
Pemphigus is classified as one of the blistering diseases. These is a close-up picture of typical lesions. Very small blisters are called vesicles. Larger blisters, like these, are called bullae.
Blood test
Blood is drawn from a vein (venipuncture), usually from the inside of the elbow or the back of the hand. A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. Preparation may vary depending on the specific test.
Poison oak rash on the arm
Poison oak rash on the arm. Several plants produce toxins that cause skin reaction. This is the appearance of poison oak dermatitis. Note the typical linear streaks produced either by scratching or brushing against the plant. (Image courtesy of the Centers for Disease Control and Prevention.)
Poison oak rash on the arm
Poison oak rash on the arm. Several plants produce toxins that cause skin reaction. This is the appearance of poison oak dermatitis. Note the typical linear streaks produced either by scratching or brushing against the plant. (Image courtesy of the Centers for Disease Control and Prevention.)

References

James WD, Elston DM, Treat JR, Rosenbach MA, Neuhaus IM. Cutaneous signs and diagnosis. In: James WD, Elston DM, Treat JR, Rosenbach MA, Neuhaus IM, eds. Andrews' Diseases of the Skin. 13th ed. Philadelphia, PA: Elsevier; 2020:chap 2.

Ko CJ. Approach to skin diseases. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 26th ed. Philadelphia, PA: Elsevier; 2020:chap 407.

Last reviewed November 4, 2020 by Elika Hoss, MD, Senior Associate Consultant, Mayo Clinic, Scottsdale, AZ. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team..

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