To Deet or Not to Deet?

By Ian K. Smith, M.D.

If April showers bring May flowers, what pops up when it rains through most of May and June as well? A bumper crop of mosquitoes, as communities from Texas to New Jersey have learned only too well this summer. The best reason to avoid being skeeter bait is, as always, the sheer human misery of dealing with all those itchy red welts. But this summer there's also the chance, admittedly small, of more serious consequences, especially now that the West Nile virus is spreading up and down the Eastern seaboard.

Last week the U.S. Centers for Disease Control and Prevention urged Americans to help reduce the risk even further by taking a few simple precautions, such as wearing insect repellent and eliminating sources of standing water where mosquitoes breed. But before you throw your favorite bug spray into a backpack and head out the door, it's important to keep a few safety tips in mind.

The most effective insect repellents contain a powerful chemical called DEET (or N, N-diethyl-meta-toluamide), developed for the U.S. military in the 1940s. DEET-based repellents last longer against mosquitoes and other biting bugs, including those that transmit Lyme disease, than the so-called natural bug sprays, which usually contain various plant oils. Since the chemical is absorbed readily into the skin, it's always best to apply any DEET products sparingly. Common side effects include rash, swelling, itching and eye irritation--usually a result of rubbing the eyes with hands that have been sprayed.

In rare cases, DEET has been linked to more serious complications like slurred speech, confusion and seizures. In most of those instances, the amount of repellent used was unusual. (In one case, a 3 1/2 year-old girl's body, bedding and pajamas were sprayed each night for two weeks.) And that brings up an important point: children are perhaps most vulnerable to the accidental misapplication of bug spray.

As a precaution, the American Academy of Pediatrics recommends that repellents used on youngsters contain no more than 10% DEET. Keep the chemical out of young mouths and eyes by applying it yourself. Lotions often work best in this respect. Remember that like perfume or cologne, a thin layer will do the trick.

Also consider wearing pants and long-sleeve shirts to minimize the amount of exposed skin, especially in dark, damp areas that are particularly thick with mosquitoes. For those worried about damaging their clothes, it's a good idea to spray a small area of material first to make sure it's DEET-proof before applying repellent to sleeves or cuffs.

Finally, when you or your children come back inside from the great outdoors, make sure all of you wash your hands and any areas that came in contact with the repellent. DEET products can be safe and effective as long as you follow instructions and don't overuse them.

Dr. Ian appears on NBC's Today show. [email protected]