S E C T I O N S

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Rash 101

The word "rash" means an outbreak of red bumps on the body. The way people use this term, "a rash" can refer to many different skin conditions. The most common of these are:

• Scaly patches of skin not caused by infection.

• Scaly patches of skin produced by fungus or bacterial infection.

• Red, itchy bumps or patches all over the place.

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 usually represent one of the conditions referred to as eczema.

Atopic dermatitis
Atopic dermatitis is perhaps the most common form of eczema. This is an 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 are hereditary, tend to run in families, and often occur together. These diseases include asthma, hay fever, and atopic dermatitis. In atopic dermatitis, the skin becomes extremely itchy and inflamed, causing redness, swelling, cracking, weeping, crusting, and scaling.

Atopic dermatitis comes and goes, often for no obvious reason. It is often worse in the winter months, when the air is cold and dry, however, moisturizing alone does not help much.

Patients with atopic dermatitis may have allergies, but most cases of atopic dermatitis are not themselves allergic. In general foods, soaps, and detergents do not play a meaningful role in producing this condition.

Atopic dermatitis is not contagious, even though patches may appear on various parts of the body.

Contact dermatitis
Contact dermatitis is an often-misused term which refers to a rash brought on by contact with a specific material which causes allergy on the skin. Common examples are poison ivy and reactions to costume jewelry containing nickel. Contact dermatitis affects just those parts of the skin touched by whatever material causes the allergy.

Treatment of contact dermatitis involves avoiding a specific cause, if there is one. Most contact dermatitis is not allergic, however, and therefore can be treated but not prevented. Effective topical (external) include topical steroids, including over-the-counter 1% hydrocortisone and many prescription-strength creams, as well as the newer nonsteroidal medications tacrolimus (Protopic) and pimecrolimus (Elidil).

There are of course many other scaly rashes. Two worth mentioning are psoriasis, an hereditary condition affecting elbows, knees, and elsewhere, and pityriasis rosea, which produces scaly patches on the chest and back and generally disappears 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 fungus 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.)

Fungal infections have nothing 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 that the drug store without a prescription, including clotrimazole 1% (Lotrisone®) and terbinafine 1% (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.

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.

Because the term is vague, some people use "rash" to describe pimply outbreaks of acne or rosacea on the face.

What should you do if you have 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 (Neosporin®), or diphenhydramine (Benadryl®)

• Antihistamines like diphenhydramine, chlortrimeton, or loratadine (Claritin®)

• 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 important, if you have any questions about the cause or treatment of a rash to contact your doctor or healthcare professional.

Source: American Academy of Family Physicians