Prescription medicines are effective for toenail infections

Q. My big toenail has become thick and yellow and has started to separate from the nail bed. It also smells unpleasant. What's wrong with my toenail, and what can I do about it?

A. Based on your description, I suspect you have a fungal toenail infection. You may have picked it up in a damp area with heavy foot traffic — a swimming pool or gym, perhaps.

Fortunately, there are several treatments you can try. A mild infection sometimes can be successfully treated by over-the-counter antifungal medicines applied to the nail. But by the time a fungal toenail infection starts to smell (as it has in your case), you should seek medical attention.

Some of my patients have heard that applying Vicks VapoRub will do the trick. The evidence for that is scanty, and I do not suggest it.

I usually send my patients with this problem to a podiatrist, a type of foot doctor. The podiatrist can do a simple test to determine if the condition is caused by a fungus, as some other conditions can produce similar changes to the toenails. Also, the podiatrist has tools to gently scrape away the infected part of the nail, including a lot of the fungus. This makes it easier for treatments to be effective.

For mild to moderate nail fungus, you can try a liquid form of ciclopirox (Penlac Nail Lacquer). This medication is applied daily like a nail polish. But it can take almost a year to complete treatment, and it is not very effective. I do not recommend it.

Prescription pills can be very effective. They include fluconazole (Diflucan), ketoconazole (Nizoral), terbinafine (Lamisil) and itraconazole (Sporanox). Although it is rare, each of these medicines can cause serious side effects and adverse interactions with other medicines you may be taking. So your doctor will need to carefully determine if they make sense for you.

Diflucan, Nizoral and Sporanox stop the fungus from growing. Lamisil prevents further growth and also kills the fungus. It takes about three months to kill the fungus and up to a year for the nail to completely grow out.

If oral medications don't eradicate your nail fungus, a doctor may have to surgically remove your toenail. This will eliminate the infection. But your nail will not grow back afterward. Some doctors are experimenting with laser treatments as an alternative to pills or surgery. Not enough is known about laser therapy for me to recommend it.

To prevent future fungal infections, wear sandals or shower shoes in public areas such as locker rooms or swimming pool areas. Wash your feet daily with soap and water and dry them thoroughly. Put on a pair of clean socks every day, and change them if you sweat heavily.

• Dr. Komaroff is a physician and professor at Harvard Medical School. Go to his website to send questions and get additional information: AskDoctorK.com.