Dear Dr. Roach: I was prescribed Lamisil (terbinafine 250 mg). I developed diarrhea after 44 pills. My doctor told me to stop taking the pills. The diarrhea has continued, and it still hasn't stopped to this day. I tried over-the-counter treatments, which did not help. I read on the Internet that this is a common side effect. I'm concerned and don't know what to do to get relief. Do you have any suggestions?


Dear E.B.: I also have read in online forums about diarrhea lasting for months after oral terbinafine, a powerful antifungal agent that can be used as a cream. However, the published reports state that the diarrhea, which isn't uncommon, usually goes away by itself pretty quickly. General advice for acute diarrhea (that is, lasting less than two weeks) includes drinking plenty of fluids with some salt and sugar, not eating at all for the first 24 hours and then only modest amounts of bland foods, such as rice, potatoes, bananas and crackers. The over-the-counter drug loperamide usually is safe. If you are having more than six bowel movements a day on this regimen after two days, it's time to call your doctor again.

Oral terbinafine rarely causes serious liver damage. Although it's not life-threatening, it can cause taste disturbances, which can become permanent. I recommend thinking twice before taking oral terbinafine.

Dear Dr. Roach: What is an exophytic cyst? I have one on my right kidney, and it has been watched closely for the past eight years. The most recent ultrasound shows that it is 2.1 cm and hasn't changed in that time. I am 78 and in good health, except for asbestos exposure. Should I get this thing removed, or let it be? I get conflicting advice.


Dear B.W.: The word "exophytic" means "growing outward," and a cyst is a fluid-filled cavity. So an exophytic cyst bulges out of the kidney and is filled with fluid. The big concern with these is whether they can be cancerous. A simple cyst, with thin walls and fluid without any solid structures, has a very low likelihood of being cancer and does not need further evaluation. If the sonogram can't show that for certain, then a CT scan is usually done.

Kidney cysts are graded according to the Bosniak category, based on their appearance by CT scan. The more complex the cyst, the higher the likelihood of cancer. Older age, being a male and asbestos exposure are risk factors for cancer of the kidney.

Despite those risk factors, if this were a simple cyst (Bosniak I or II) and unchanged in eight years, it is very unlikely to be cancer, and I would recommend letting it be. However, if it were a Bosniak category III or higher, I would discuss biopsy with the urologist.

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