What are the different types of common skin rashes?

Whether it is used by patients or doctors, the word "rash" does not have an exact meaning or refer to a specific disease or kind of disorder. It's a general term that means an outbreak of bumps on the body that changes the way the skin looks and feels. Rashes can be localized to one area or else be widespread. The way people use this term, a rash can refer to many different skin conditions. Common categories of rash are

• scaly patches of skin not caused by infection
• scaly patches of skin produced by fungal or bacterial infection, and
• red, itchy bumps or patches all over the body.

Although rashes are seldom dangerous, self-diagnosis is not usually a good idea. Proper evaluation of a skin rash requires a visit to a doctor or other healthcare professional. The following guidelines may help you decide what category your rash falls into.

Scaly patches of skin not caused by infection

Scaly, itchy skin patches often represent one of the conditions referred to as eczema.

Atopic dermatitis: Atopic dermatitis is perhaps the most common form of eczema. This is a hereditary skin problem that often begins in childhood as chapped cheeks and scaly patches on the scalp, arms, legs, and torso. Later in childhood, atopic dermatitis may affect the inner aspects of the elbows and knees. Adults get atopic dermatitis on the hands, around the eyelids, on the genitals, as well as on the body as a whole.

The word "dermatitis" means inflammation of the skin. "Atopic" refers to diseases that may be associated with allergies and tend to run in families. Atopic diseases include asthma, hay fever, and atopic dermatitis. In fact, people may refer to what doctors call eczema as "allergic skin." However, this is usually not the case. Patients with atopic dermatitis may have allergies, but most cases of atopic dermatitis are not themselves allergic.

Eczema comes and goes on its own schedule, in a manner not related to the allergy usual suspects—foods, soaps, and detergents—which may be blamed for flare-ups. In most cases, changing diet and detergents helps eczema very little.

Atopic dermatitis is often worse in the winter months, when the air is cold and dry, so that frequent washing may irritate the skin and aggravate the condition Although the skin feels "dry," it really isn't; it is inflamed, and therefore moisturizing alone does not help much.

Skin affected by atopic dermatitis becomes extremely itchy and inflamed. It may look red, swollen, and cracked. In some cases, the skin can also weep and crust. Liquid that oozes out of such crusts is often not infected; what comes out is the body's normal tissue fluid. Treatment specific for eczema is helpful, not antibiotics.

Patches of atopic dermatitis may appear on various parts of the body, but the condition is not contagious. It may appear off and on throughout life, but there may be long intervals between outbreaks. Also, the condition does not get progressively worse with age; if anything, it is most extensive during childhood.

Treatment of eczema involves minimizing irritation if that is contributing to the problem and using prescription-strength steroids (cortisone creams). Nonsteroidal creams like tacrolimus (Protopic) and pimecrolimus (Elidel) have become less popular both because of relative lack of effectiveness and concerns about safety. Tap water soaks with Burow's solution (available without prescription) can help dry up atopic dermatitis in its oozy stages.

Contact dermatitis: Contact dermatitis is a rash that is brought on either by contact with a specific material that causes allergy on the skin or with something that irritates the skin, like too-frequent hand washing.

Common examples of contact dermatitis caused by allergy are poison ivy and reactions to costume jewelry containing nickel. With occasional exceptions, allergic contact dermatitis affects just those parts of the skin touched by whatever material causes the allergy, as opposed to atopic dermatitis, which can be widespread because, as explained above, it is not an allergy to a specific substance.

Treatment of contact dermatitis involves avoiding the allergen that caused it, if there is one, or minimizing whatever exposure is irritating the skin (water on the hands, solvents at work, saliva around the mouth from lip licking). Effective treatments include topical steroids, including over-the-counter 1% hydrocortisone and many prescription-strength creams. Here too, nonsteroidal creams like tacrolimus and pimecrolimus are used less than they once were. Tap water soaks with Burow's solution cab help dry up oozy contact dermatitis as well.

There are of course many other scaly rashes. Two worth mentioning are psoriasis, a hereditary condition affecting elbows, knees, and elsewhere, and pityriasis rosea, which primarily affects teens and young adults, producing scaly patches on the chest and back and generally disappearing in about a month. Xerosis, very dry skin, may also appear as a rash during the cold, dry months of the year.

Scaly patches of skin produced by fungal or bacterial infection

When infections appear as rashes, the most common culprits are funguses or bacterial infections.

Fungal infections: Fungal infections are fairly common but don't appear nearly as often as rashes in the eczema category. Perhaps the most common diagnostic mistake made by both patients and non-dermatology physicians is to call scaly rashes "a fungus." For instance, someone with several scaly spots on the arms, legs, or torso is much more likely to have a form of eczema or dermatitis than actual ringworm (the layman's term for fungus). Likewise, yeasts are botanically related to fungi and can cause skin rashes. These tend to affect folds of skin (like the skin under the breasts or the groin). They look fiery red and have pustules around the edges. As is the case with ringworm, many rashes that are no more than eczema or irritation get labeled "yeast infections."

Fungus and yeast infections have little to do with hygiene—clean people get them too. Despite their reputation, fungal rashes are not commonly caught from dogs or other animals, nor are they easily transmitted in gyms, showers, pools, or locker rooms. In most cases, they are not highly contagious between people either.

Treatment is usually straightforward. Many effective antifungal creams can be bought at the drugstore without a prescription, including 1% clotrimazole (Lotrimin, Mycelex) and 1% terbinafine (Lamisil).

Bacterial infections: The most common bacterial infection of the skin is impetigo. Impetigo is caused by staph or strep germs and is much more common in children than adults. Again, poor hygiene plays little or no role. Nonprescription antibacterial creams like bacitracin or Neosporin are not very effective. Oral antibiotics or prescription-strength creams like Bactroban are usually needed.

Red, itchy bumps or patches all over the place

Outbreaks of this sort are usually either viral or allergic.

Viral rash: While viral infections of the skin itself, like herpes or shingles (a cousin of chickenpox), are mostly localized to one part of the body, viral rashes are more often symmetrical and everywhere. Patients with such rashes may or may not have other viral symptoms like coughing, sneezing, or an stomach upset (nausea). Viral rashes usually last a few days to a week and go way on their own. Treatment is directed at relief of itch, if there is any.

Allergic drug rash: Most allergic drug rashes start within two weeks of taking a new medication, especially if the person has taken the drug before. It is very unlikely for medicine that has been prescribed for months or years to cause an allergic reaction. Because there is usually no specific test to prove whether a rash is allergic, doctors may recommend stopping a suspected drug to see what happens. If the rash doesn't disappear within five days of not taking the medication, allergy is unlikely.

Although foods, soaps, and detergents are often blamed for widespread rashes, they are rarely the culprit.

Other rashes

Hives (urticaria) are itchy, red welts that come and go on various parts of the body. Most hives are not allergic, run their course, and disappear as mysteriously as they came.

What is the treatment for a rash?

Most rashes are not dangerous to a person or people in the vicinity (unless they are part of an infectious disease such as chickenpox). Many rashes last a while and get better on their own. It is therefore not unreasonable to treat symptoms like itchy and/or dry skin for a few days to see whether the condition gets milder and goes away.

Nonprescription (over-the-counter) remedies include:

• anti-itch creams containing camphor, menthol, pramoxine (Itch-X), or diphenhydramine (Benadryl);



• antihistamines like diphenhydramine, chlortrimeton, or loratadine (Claritin, Claritin RediTabs, Alavert); and



• moisturizing lotions.

If these measures do not help, or if the rash persists or becomes more widespread, a visit to a general physician or dermatologist is advisable.

There are many, many other types of rashes that we have not covered in this article. So, it is doubly important, if you have any questions about the cause or treatment of a rash, to contact your doctor. This article is really just as the title indicates: "Rash 101: Introduction to Common Skin Rashes."

A word on smallpox vaccination in patients with rashes

People with atopic dermatitis or eczema should not be vaccinated against smallpox, whether or not the condition is active. In the case of other rashes, the risk of complications is much less. Consult your doctor about the smallpox vaccine.

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