Definition and Overview

A skin rash, also medically known as dermatitis, is a skin condition characterized by irritation, swelling or puffiness of the skin. A rash is not considered a specific diagnosis, but a general term to describe an outbreak or abnormal change in the skin’s color or texture.

Types and Causes of Rashes

Today, there are over 20 conditions associated with skin rash. Some of the most common non-infectious rashes and their causes are as follows:

• Seborrheic dermatitis - This is perhaps the single, most common skin condition that causes small bumps and rashes to appear on the scalp, cheeks, brows and forehead

• Atopic dermatitis or eczema - Characterized by red, itchy and scaly bumps, this tends to occur in people with asthma or allergies

• Contact dermatitis - rashes caused by direct contact with allergens (such as fabric, plant, chemical or substance) that irritate the affected area of the skin

• Stasis dermatitis - a serious type of dermatitis characterized by weepy blisters and swelling of the lower legs caused by poor circulation in the veins

• Psoriasis - a kind of rash characterized by silvery flakes on the skin of the scalp, elbows and knees that eventually fall off

• Nummular eczema - associated with dry skin especially during winter and cold seasons, this condition is characterized by weepy dermatitis that appear as coin-shaped plaques

• Hives - these are red, itchy bumps that appear and recur very quickly and subside in less than 24 hours

• Heat rash (miliaria) - as suggested by its name, this skin irritation is caused by the overproduction of the sweat glands during hot and humid season; they may appear as very small blisters or a red cluster of pimples in the upper chest, neck, elbow creases and under the breasts

• Rashes due to insect bites - bites from bedbugs, ticks, mosquitoes and other insects can cause rashes to appear in the affected area; insects may also bring viral diseases such as Lyme disease or dengue fever, which are also characterized by formation of rashes all throughout the body

• Rashes due to drug interruption - certain medications can cause skin rashes to appear due to an allergic response

• Folliculitis - an infection of the hair follicles on the scalp and skin can cause red and tender patches or small blisters

Rashes may also be caused by bacterial, viral and fungal infections, such as those caused by:

• Staphylococcus, Streptococcus and Pseudomonas bacterial infections
• Shingles or Herpes zoster infections
• Measles
• HIV
• Viral childhood illnesses including chicken pox, roseola, rubella, and scarlet fever
• Tinea, candida (“yeast”) or ringworm infections

There are also certain medical conditions that can cause the onset of rashes. These include rheumatoid arthritis and hypothyroidism (especially in young patients), Kawasaki disease (a rare disease that causes blood vessel inflammation) and Lupus erythematosus (an auto-immune disease).

Treatment Options for Rashes

Most simple rashes will improve with proper skin care and avoidance of allergens or irritants. Gentle cleansing with hypoallergenic soap, leaving the affected area exposed to air, application of calamine lotion, or over-the-counter hydrocortisone creams can soothe many rashes until they subside in a day or two.

Medical treatment for more complex to severe rashes can be categorized into two kinds: treatments for infectious and treatment for non-infectious rashes. Most non-infectious rashes are easily treated with:

• Cortisone creams to relieve itching
• Lubrication and skin care lotions to prevent dryness
• Topical steroids to control the rashes
• Antihistamine medication to control symptoms and lessen itching
• Antibiotics for rashes that have developed infection
• Avoidance of the rash-causing drug or substance
• In severe cases, oral steroids to clear the rash

Infectious rashes caused by fungus, virus and bacteria are often treated using any or a combination of the following:

• Topical and oral anti-fungal medications such as clotrimazole or fluconazole
• Oral or intravenous anti-viral medications such as famciclovir, acyclovir, and valacyclovir
• Topical or oral antibiotics or anti-bacterial medications such as penicillin and cephalosporin
• Vaccination to prevent infections such as chickenpox and shingles

The mode of treatment usually prescribed depends on the underlying cause and the severity of the rash.

When to See a Doctor

Rashes are very common conditions. Although they cause a great deal of discomfort, they are often not dangerous and do not require immediate medical attention. However, if you experience a rash or skin irritation that has persisted for at least two days or have recurred, it is best to see consult your doctor. Visiting your family physician can help you pinpoint the cause of your rashes and find the right treatment method available. Your general practitioner may also refer you to a dermatologist, allergologist or other specialists depending on the symptoms exhibited.

There are also rare instances when rashes can be an indication of a life-threatening medical condition. It is best to see a doctor or dermatologist immediately if:

• You encounter a rash or blister that affects the entire body
• The rash is affecting both the skin and mucous membranes (mouth, nose, eyes, anus, or genitals)
• The rash is accompanied by other symptoms such as joint pain, sore throat, and fever
• Your symptoms worsen despite home care or over the counter remedies

What to Expect When You Visit the Doctor

To properly diagnose a rash, your health care provider will perform a physical examination and ask you questions about your rash. Be sure to provide them important information such as:

• Exact areas of the body affected
• Medications or remedies you have taken
• Whether you used any soap, detergent, lotion or cosmetics
• Food you have recently taken
• Places you have recently gone to
• Possible insect bites
• Other symptoms you are experiencing
• Any underlying medical problems

Your doctor may perform further tests to diagnose your rash further including allergy testing and blood tests. A skin biopsy may also be performed where a sample of your skin may be scraped or removed for further laboratory testing.

References:

• Armstrong CA. Examination of the skin and approach to diagnosing skin diseases. In: Goldman L, Ausiello D, eds. Cecil Medicine. 24th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 444.
• Cole, Gary W. MD., “Rash 101: Introduction to Common Skin Rashes” Available: http://www.nlm.nih.gov/medlineplus/ency/article/003220.htm
• U.S. National Library of Medicine. “Rashes” Available: http://www.nlm.nih.gov/medlineplus/ency/article/003220.htm