Start sneezing and before you know it, your friends are suggesting you try this or that herb or homeopathic remedy. You wonder if you should follow their advice. You've heard about complementary and alternative medicine (called CAM for short), but you don't know that much about it. Before you decide, get the facts. And make sure to talk with your doctor before you try something new dealing with alternative health care — especially if you're pregnant or nursing, take medications, or have chronic health problems.

Because of the increasing popularity of complementary and alternative medicine — nearly 40 percent of U.S. adults report using it — doctors are learning more about these nonconventional approaches. The most popular case is alternative weight loss and a health care for disabled people. When doctors use the term "alternative medicine," they're referring to practices not typically used in conventional Western medicine. Exactly what's considered alternative medicine changes constantly as more treatments undergo study and move into the mainstream. When an alternative medicine therapy is used in addition to — not instead of — conventional therapy, it's called complementary. And when you use a complementary therapy in addition to a conventional one, it's called integrative medicine.

One reason for the lack of research in complementary and alternative treatments is that large, carefully controlled medical studies are costly. Trials for conventional medications or procedures are often directly or indirectly funded by the government or drug companies, giving conventional treatments more resources to do studies. CAM trials are more difficult to fund, so there are fewer trials. Nonetheless, a number of studies are under way on CAM treatments ranging from herbal health care to yoga. The National Center for Complementary and Alternative Medicine is the lead U.S. agency that supports research into complementary and alternative treatments, and it makes research findings available on its Web site.