(FORTUNE Magazine) – You might be suspicious of a single pill that reportedly helps treat depression, osteoarthritis, liver disease, multiple sclerosis, Parkinson's disease, and migraine headaches. You'd be even more suspicious if that pill didn't require a prescription. But here's the most surprising thing: S-adenosylmethionine (commonly referred to by the short name SAM-e, or "sammy") might actually work.

Since the 1970s, SAM-e--a naturally occurring compound that helps regulate neural, hormonal, and metabolic reactions--has been prescribed in Europe to treat a host of ailments. In Spain, SAM-e is prescribed for liver disease; in Germany, it's prescribed for osteoarthritis; and in Italy, SAM-e outsells Prozac for depression. Two years ago, BASF, Germany's vitamin and chemicals giant, introduced SAM-e to the U.S. as a dietary supplement. Since then sales have taken off, reaching $12 million in 1998 and $130 million in 1999. This year they should hit $180 million. Officials at retailer GNC, which sells about 10,000 products, say that SAM-e already ranks among the top 200.

The Food and Drug Administration doesn't regulate the product like a prescription drug--and doesn't plan to--because BASF has provided the necessary clinical results to sell the pill as a dietary supplement. The FDA would only get involved if SAM-e had any dangerous side effects. So far that's not the case, though some experts think extremely high doses of SAM-e could lead to a greater risk of heart disease.

In an unscientific survey, FORTUNE talked to four random Manhattan pharmacists about the pill. All reported that customers were buying the pill and, more significant, all four were taking it themselves.

One downside: These pills aren't cheap. Depending on what you're treating and the dosage you choose, SAM-e can cost up to $8 to $10 a day. For that price, this so-called panacea had better put a smile on your face.

--Julia Boorstin