The day after George Zimmerman killed Trayvon Martin, his family doctor diagnosed him with a broken nose, two black eyes, and two lacerations on the back of his head. The attorney for Martin’s family questioned the doctor’s findings, noting that medical personnel “didn’t even put a Band-Aid” on Zimmerman’s head on the night of the shooting. Is there ever a good reason to use a small adhesive bandage?

Not really. Adhesive bandages protect wounds from reinjury and save your friends and family the disgusting sight of your scab. For most cuts and scrapes, however, they don’t do much to speed up the healing process. If the bandages were better able to trap moisture, they might speed the formation of a new layer of skin. If they could absorb more of the fluid that seeps out of a wound, they might help stave off the formation of a scab (which slows recovery). If they were more effective at keeping out bacteria, they could prevent the puss and swelling that comes with an infection. But adhesive bandages aren’t very good at any of these tasks. And when it’s time to tear them off, the process can damage the fragile, newly formed skin underneath.

That’s not to say you should leave your wounds exposed. Studies on pigs have shown that appropriately dressing a wound speeds recovery time by around 30 percent. It’s just that adhesive bandages may not be your best option. Choosing an appropriate dressing depends on the type of wound. For deep wounds, or wounds that are slow to close, the best choice is often a hydrocolloid dressing, which can absorb relatively large amounts of fluid. (A commercial example is 3M’s Tegaderm.)

For most other wounds, the most important consideration is keeping the wound moist. The growth factors that assist in rebuilding skin don’t work in a dry environment. Plus, a moist surface allows new skin cells to move across the wound more easily. If the laceration dries out, the cells have to tunnel beneath the epidermis and push the scab upward. A polyurethane dressing can trap the moisture more effectively than a standard adhesive bandage. (In fact, even ordinary kitchen-grade plastic wrap may be a better choice.) If you choose an adhesive bandage, it’s best to apply a coating of ointment to the wound first, which will provide a much better moisture barrier than the bandage alone. Another good option is a cyanoacrylate, which works like a glue to make a water-tight barrier around the wound.

Most people have been told at some point that a wound has to “breathe.” This old wives’ tale is probably based on a phenomenon known as “tissue maceration”—when moisture turns the skin around a wound eggshell-white and prune-like. This can result from a bandage that is left on too long, or from an excess of fluid seeping from a wound. But, as a general rule, the best dressings seal the wound off from the outside world.

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Explainer thanks Pooja Agrawal of Brigham and Women’s Hospital, Stephen Davis of the University of Miami Miller School of Medicine, Harriet Hopf of the Wound Healing Society, and Jonathan Zenilman of the Johns Hopkins University School of Medicine.

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