Q: Do you need to see a doctor for diagnosis and treatment of athlete’s foot?

A: Perhaps the skin in between your toes is itchy. Or the skin on the sides of your feet is flaking and irritated.

These are classic signs of athlete's foot. Doctors call it tinea pedis and it's a common fungal infection, affecting 15% to 25% of people at any one time.

"Most people want to treat athlete's foot," said Shari Lipner, a dermatologist at Weill Cornell Medicine in New York. Even when the itching and burning symptoms are very mild, the condition is unsightly. Also, the fungus can invade the nail — and nail fungus is much harder to treat, Lipner said.

But you don't necessarily need to see a doctor. It's OK to try an over-the-counter product on your own. Look for those that contain an antifungal medication such as terbinafine (Lamisil), clotrimazole (Lotrimin), tolnaftate (Tinactin), miconazole (Micatin), or undecylenic acid (Cruex). Other products, such as those containing tea tree oil or "natural" salts, have little evidence to back their use, Lipner said.

"Generally, we recommend treating for about a month," Lipner said.

But if your symptoms don't improve after a couple of weeks, you should probably see a doctor.

Adam Friedman, a dermatologist at George Washington University School of Medicine and Health Sciences, said even doctors cannot always identify athlete's foot correctly. He said he found that dermatologists looking at still images may make errors in identifying various skin conditions. And errors can have consequences. Steroid creams, for example, might be appropriate for eczema but can make athlete's foot worse.

Dermatologists can diagnose athlete’s foot by taking fungal cultures or performing a two-minute, in-office procedure called a potassium hydroxide (KOH) test.

The fungi involved are usually one of two species of Trichophyton, either rubrum or mentagrophytes.

"Our skin cells are foie gras to them," Friedman said. "These organisms just like the top layer of skin." But when fungus take up residence on the surface, he says, "They can open the door to bacteria and other infections to cross the barrier."

For instance, athlete's foot might start out scaly red, but if it becomes red, swollen and painful, it's a warning sign of something else. Inflammation might indicate a bacterial infection, even a serious one such as cellulitis.

Untreated athlete's foot means you're harboring fungal growth. That fungus can spread to the toenails.

"With nail fungus, it's even more important to see a board-certified dermatologist," Lipner said.

Over-the-counter ointments, powders and sprays don't work against nail fungus. Typically, this condition is treated with oral antifungal medications, or one of the newer topical preparations, which are pricey and by prescription only.

It's important to treat nail fungus because it serves as a reservoir of organisms, Friedman said. The first-line treatment is oral terbinafine. Toenails grow slowly, so you'll have to wait for the unsightliness to grow out. "It can take a year to look normal," Friedman said.

Once you’ve rid yourself of athlete’s foot, you might want to focus on preventive measures. Lipner advised wearing flip flops on pool decks and in locker room showers, wearing moisture wicking socks, and keeping your nails short.

"Probably the biggest risk factor is a family member with athlete's foot," Lipner said. You're sharing floors and showers in your home. "Genetics may play a role, but exposure is the key thing."

If you're prone to athlete's foot or have a history of nail fungus, Lipner recommended daily treatment with a drugstore antifungal product — it reduces your chance of recurrence threefold, she said.

“Athlete’s foot tends to be a chronic condition,” Lipner said. “Expect it to come back. Expect to treat it again.”