Blisters

WHEN TO SEE YOUR DOCTOR

* You've just started taking a new medication (even one you've taken before without problems.)

* You are elderly or have diabetes and suddenly get blisters on your feet or ankles.

* Your blisters don't start healing after a day or two, or become pus-filled, red, hot or painful.

* You have a blister that's larger than two inches in diameter.

* You have painful blisters around your mouth.

* You don't know what's causing the blisters.

What Your Symptom Is Telling You

You spend a day in the sun—perhaps hiking in new boots or rowing a canoe. Say hello to blisters.

Things like stiff shoes or rowing—if you're not used to it—can cause friction blisters. And blistery sunburn is inevitable if your unprotected skin is exposed to the sun long enough.

The causes of most blisters are obvious, says Guy F. Webster, M.D., Ph.D., assistant professor of dermatology and director of the Center for Cutaneous Pharmacology at Thomas Jefferson University in Philadelphia. "Other causes are a little more obscure, though," he says. For example, reactions to medications—including some antibiotics, diuretics and pain relievers—can raise blisters anywhere or everywhere on your body.

There are also blister-raising infectious diseases—ranging in severity from a touch of athlete's foot or herpes (fever blisters) to extensive blistering from shingles (adult chickenpox).

Finally, close encounters with substances that you're allergic to—poison ivy, for example—can raise whole patches of itchy blisters.

No matter what the cause, blisters are all alike: "They're separations of the skin's outer layer from its inner layer," says Ellen Cohen-Sobel, D.P.M., Ph.D., associate professor of podiatric orthopedics at New York College of Podiatric Medicine in New York City. Liquid between the estranged layers forms a little water balloon.

Symptom Relief

How you treat a blister will depend very much on how many there are and the cause. Here are a few things to be aware of.

Leave it alone if you can. Intact blisters are best left undisturbed. "By not popping a blister, the skin underneath can heal in a happy environment. And if it's bathed in body fluids, it's happy," says Dr. Webster.

"If you're hiking and a large blister is physically in the way, you might make an exception and drain it," says Jerold Z. Kaplan, M.D., medical director of the Alta Bates Burn Center in Berkeley, California. A doctor does this by drawing fluid out with a sterile syringe, Dr. Kaplan explains. "To doctor yourself, hold a needle under a flame or use rubbing alcohol to sterilize it. Then gently poke a hole near the edge of the blister, push the fluid out and cover the area with a bandage. Don't rip the blister's whole roof off," he instructs. (It might be a good idea to include a couple of needles in your backpack first-aid kit.)

Patch the roof. "If a blister's already rubbed open, fold the skin back in place so you have your own skin protecting the soreness," says Mark D. Sussman, D.P.M., of Wheaton, Maryland, a podiatrist and coauthor of several foot-care books, including The Family Foot-Care Book. Then dab it with antiseptic first-aid cream and cover it with a fabric—not plastic—bandage. Pharmacies and some sporting goods stores carry products made specifically for covering blisters as well.

Walk away from pressure. The best way to take pressure off intact foot blisters is to pad around them with adhesive felt or foam, which you can buy in a drugstore. Nonmedicated callus or corn pads work too, says Dr. Sussman. Bandage the area and change shoes to eliminate the source of friction. Make sure there is a small area of nonblistered skin around the pad so it doesn't impinge on the edges of the blister.

Protect the little ones. Protect small, ruptured blisters with something nonadherent, such as Vaseline Gauze, Dr. Kaplan suggests. Then cover the Vaseline Gauze with a plain gauze bandage. You can coat small broken blisters—like burst sunburn blisters—with Preparation H, says Dr. Kaplan. "It's not an FDA-approved use, but it will help them heal," he says.

Solve a blister mystery. Blisters from medications and most infectious diseases should be seen by a doctor. (In fact, show any blisters that you can't account for or don't go away in one week to your doctor.) Treatment may include switching medications or an antibiotic to clear up an infection.

See also Cold Sores; Foot Itching; Rashes