Rashes involve changes in the color, feeling or texture of your skin.
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.
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
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, itchy patches over joints and along the scalp. 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:
Most simple rashes will improve with gentle skin care and by avoiding irritating substances. Follow these general guidelines:
- Avoid scrubbing your skin.
- Use as little soap as possible. Use gentle cleansers instead.
- 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, psoriasis, or shingles. Oral antihistamines may help relieve itchy skin.
When to Contact a Medical Professional
Call 911 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.
Skin redness or inflammation; Skin lesion; Rubor; Skin rash; Erythema
- Poison oak rash on the arm
- Erythema toxicum on the foot
- Erythema annulare centrifugum - close-up
- Psoriasis - guttate on the arms and chest
- Psoriasis - guttate on the cheek
- Systemic lupus erythematosus rash on the face
- Poison ivy on the knee
- Poison ivy on the leg
- Erythema multiforme, circular lesions - hands
- Erythema multiforme, target lesions on the palm
- Erythema multiforme on the leg
James WD, Berger TG, Elston DM. Cutaneous signs and diagnosis. In: James WD, Berger TG, Elston DM, eds. Andrews' Diseases of the Skin: Clinical Dermatology. 11th ed. Philadelphia, PA: Elsevier; 2016:chap 2.
Shaw JC. Examination of the skin and an approach to diagnosing skin diseases. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 25th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 436.
Review Date 10/14/2018
Updated by: Michael Lehrer, MD, Clinical Associate Professor, Department of Dermatology, University of Pennsylvania Medical Center, Philadelphia, PA. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.