Herbal remedies have been around for thousands of years, but they've only recently started to gain popular acceptance in America. Americans spent $2.5 billion on herbal medicines in 1996, and that figure has been rising by about 25 percent a year since then. 

  While supporters say that herbal remedies can aid in the treatment of everything from the common cold to minor depression, very little scientific proof exists to support these claims. If you're one of the millions of Americans interested in herbal remedies, keep the following precautions in mind. Just because a product is advertised as "organic" or as having "all natural ingredients" does not mean that it is harmless. 

  One of the major problems with relying on herbal remedies is that, unlike prescription medications, herbs are not regulated by any government agency. So there's no guarantee that the brand you buy contains an effective amount of the active ingredient, or is free of impurities. Researchers at the Mayo Clinic in Rochester, Minn., also point out that labeling on herbal remedies might be inaccurate or incomplete, and that some manufacturers use potentially dangerous herbs.

  Another problem with herbal remedies is the fact that few scientific studies have been conducted on their effects. Many of the more popular herbs on the market right now base their claims on various European studies. Here's an overview of some of them: 

• Echinacea is purported to help prevent or alleviate the symptoms of the common cold. Researchers in Italy and Germany have reported findings that support this claim, but their results are still not widely accepted by most American medical organizations. And, the herb may cause problems for people who are pregnant, diabetic or have autoimmune conditions such as those caused by lupus, multiple sclerosis or AIDS.
• Ginkgo biloba may improve circulation and memory, and perhaps slow the onset of Alzheimer's disease. However, taking the herb for more than two years has reportedly caused bleeding inside the skull in some individuals. And it may also cause minor gastrointestinal disturbances. 
• Hypericum perforatum, or St. John's Wort, was shown to help treat depression in a 1996 study published by the British Medical Journal. Further studies are currently underway in the U.S. to confirm the European results. But, experts strongly advise that St. John's Wort be taken only under the supervision of a qualified medical professional. Depression is a serious condition, and patients should never try to self-diagnose or treat themselves. 

  In addition, the Food and Drug Administration has linked the following five herbal supplements to serious side effects or death:

• Chaparral - liver damage
• Comfrey - liver damage
• Ephedra - high blood pressure, racing pulse, muscle injury and nerve damage
• Lobelia - breathing problems, racing pulse, sweating, coma and death
• Yohimbe - nervous disorders, paralysis, digestive problems and death*

  Keep in mind that mixing herbal products with either prescription or over-the-counter drugs could result in dangerous side effects. For example, some brands of St. John's Wort contain a natural antidepressant chemical known as monoamine oxidase inhibitor, or MAOI, which can cause dangerously high blood pressure levels when taken in conjunction with any one of a number of drugs. Some popular herbal products have an anticoagulating (thinning) effect on the blood which can cause uncontrolled internal bleeding and death when mixed with other prescribed medications that also thin the blood.

  Despite possible negative effects, herbal remedies aren't going away anytime soon. And they may gain even more mainstream acceptance as researchers in the U.S. shed additional light on the subject through further tests. 

  If you're interested in taking an herbal remedy, be sure to consult your doctor or a nutrition expert first. Never consider mixing herbal products with prescription medications or over-the-counter medicines without checking with your physician. 

*The American Dietetic Association's Complete Food & Nutrition Guide by Roberta Larson Duyff, MS, RD, CFCS