Men whose sex life has gone from gangbusters to game-over commonly turn to herbal supplements to find their erections again.

But what evidence exists that these "Viagra alternatives" will get you back in the game without risks to your health?

The fact is, it's largely "buyer beware" with therapies like these, which are not approved and are only loosely regulated by the Food and Drug Administration.

Even so, many healthcare providers believe they can help with sexual dysfunction. According to Marc Bonnard, M.D., author of The Viagra Alternative (Healing Arts Press, 1999), certain herbs may actually have an advantage over pharmaceutical alternatives. Writes Bonnard, a psychiatrist specializing in sex therapy: "Herbs work in a more leisurely fashion," replacing the mind-body balance that is "so important for a positive sexual experience."

Some alternative treatments may affect the physiological functions that contribute to sexual dysfunction, such as hormonal imbalances and slowed circulation. But take care when trying these supposed sex boosters — Bonnard, like other experts, emphasizes that even "all-natural" over-the-counter herbal products are potentially potent and can have toxic side effects.

The following are among the herbal ingredients in the most popular sexual supplements:

Damiana. Popular as an aphrodisiac in Mexico, the plant-derived leaves and stems are available in tablet form, or the dried leaves can be prepared in a tea. But, advise Mayo Clinic experts, know that the product has not been tested in humans.

DHEA (dehydroepiandrosterone). The hormone produced by the adrenal glands is necessary for the production of testosterone as well as estrogen. Some small scientific studies have shown promise in helping men with low testosterone, but only a small minority of impotence problems can be blamed on low levels of the hormone.