Reality Check: Can Listerine ward off a swarm of mosquitoes?

THE BELIEF:

Listerine can ward off a swarm of mosquitoes.

THE FACTS:

Listerine may have its place in the medicine cabinet, but to some resourceful outdoors types, it has a second life. Pour a couple of ounces in a spray bottle, the story goes, spritz it in the air at the next barbecue, and -- presto! -- you have a cheap and pleasant-smelling mosquito barrier.

A primary ingredient in Listerine and several other commercial mouthwashes is eucalyptol, a natural oil that is also an active ingredient in botanical repellents. According to the federal Centers for Disease Control and Prevention, oil of lemon eucalyptus is one of the most effective mosquito repellents, along with DEET and picaridin.

Several studies, including one by the London School of Hygiene and Tropical Medicine, have found that eucalyptus-based repellents can be extremely effective, and nontoxic to humans. But they often contain the compound in concentrations as high as 75 percent; the concentration in mouthwash is usually below 1 percent. Mouthwashes also contain water and alcohol, so they tend to evaporate quickly. Commercial repellents, on the other hand, are designed to last for hours.

THE BOTTOM LINE:

Listerine might discourage buzzing mosquitoes -- but not for long.

-- The New York Times