An infection of toenail fungus, or onychomycosis, occurs when fungi infect one or more nails. As the nail fungus spreads deeper into the nail, it may cause nail discoloration, thickening and the development of crumbling edges, all of which can lead to an unsightly and potentially painful problem. Onychomycosis is difficult to treat, and infections recur easily. Toenail fungus affects approximately 23 million people in the US - about 10% of all adults. Currently available treatments for toenail fungus are lacking. Even the most effective oral medications are successful only about half of the time. Topical medications are successful less than 10% of the time. Recently, research has found laser therapy to show promise as a novel alternative treatment for toenail onychomycosis. Unlike medication-driven treatments for toenail fungus which can have many side effects including serious ones such as liver toxicity, laser therapy presents minimal risk of side effects. Laser therapy is applied to toenail onychomycosis by shining a laser light through the toenail. The laser light vaporizes the fungus while leaving the skin and surrounding tissue unharmed.