Ever since a 2002 study found that the use of hormone replacement therapy increased the risk of heart attacks, breast cancer and strokes, women have been looking for a safe alternative to control the often debilitating symptoms of menopause.

The search has led to a booming market for so-called bioidentical hormones — hormones derived from plant sources and said to mimic those produced by the human body.

Dr. Allan E. Sosin and his Institute for Progressive Medicine specialize in “natural therapies” for a number of medical conditions, including menopause.

“Pellets have been around for 50 years, so this is nothing new,” Sosin told FOXNews.com. “They’re not FDA approved, and when the other (prescription) hormones came out, people went to those. But now doctors have stopped prescribing those and people stopped taking them, so the pellet therapy has come on really strong.”

Not everyone is sold on the benefits of “natural” hormone therapy, however.

The U.S. Food and Drug Administration, the American College of Obstetricians and Gynecologists and the North American Menopause Society have previously warned consumers that there are no studies to back the safety or effectiveness of bioidentical and custom-made hormone therapies.

In January, the FDA told seven producers of bioidentical hormones to stop making and selling them, adding that these alternative hormone therapies are no safer than other hormone replacement therapies.

But Sosin believes hormone pellet therapy can alleviate the symptoms of menopause — including loss of bone density, hot flashes, mood swings and waning sexual desire — without the dangerous side effects of hormone replacement medications, such as Prempro and Premarin, as well as those carried by synthetic pills and creams.

“Natural hormones are safer because they are like those made by the human body,” Sosin added. “Synthetic hormones are not what’s made from the human body so you don’t know what kinds of side effects they carry. Not all hormones made by drug companies are artificial. Premarin is made from horses' urine. It’s natural, but it doesn’t produce the same effects as the natural hormones found in women.”

Sosin said he is not profiting from the sale of hormone pellets and is not affiliated with any manufacturers of the products.

He said the pellets, which are formulated with the estrogen-like compounds estradiol and estriol, as well as progesterone and testosterone, must be obtained and implanted in the hip area by a doctor. They are gradually released in the body over an extended period of time.

“Older women in their 60s and 70s find them helpful for osteoporosis, which the pellets containing testosterone are very good for,” he said. “Women also say they experience a vast enhancement in sexual activity from the pellets.”

Dr. James Simon, a Washington D.C. reproductive endocrinologist and professor at the George Washington University, said he first used hormone pellet therapy in 1969.

"I really think it's a personal choice," he said. "I work in Washington so a lot of the women I see who want it are from Europe where the therapy is more commonly used. I think it's not as frequently used as other forms of hormone therapy because it's not covered by insurance and because of the inconvenience of having it put in at least twice, if not three times a year. And it does leave a scar."

He said the pellets at one time were FDA approved, but as use of the therapy declined in favor of other HRTs, manufacturers of the pellets found it no longer cost effective to maintain approval.

The college of obstetricians and gynecologists, and the menopause society also warn that bioidentical products may vary in the quality, purity and potency of the hormones.

Anecdotal evidence has shown that they carry the similar bothersome side effects as traditional HRTs, including increased bloating, headaches, breast tenderness and anxiety and mood swings.

Simon said there is some concern that the pellets, because they are not regulated, may subject users to an extraordinarily high amount of estrogen and testosterone.

"There was one study about 20 years ago that found that there was a higher breast cancer risk with this particular route of administration compared to other forms of estradiol therapy," he said. "I really think that this is what the FDA was getting at when it went after the makers of bioidentical hormones earlier this year; that is thinking that these are some how safer than other methods of hormone replacement therapy is totally erroneous."