Tempted by those ads for natural herbal products that can help you lose weight fast or help suppress your appetite? Sound like an easy way to get rid of those extra pounds? They may sound good, but do they work? How safe are they?

Manufacturers of herbal products don't have to prove that their products are safe or effective and don't have to list ingredients on the labels.

Even the experts don't know for sure how safe many of these products are. That doesn't mean there aren't safe products -- it means you have to be wary of "miracle" claims.

Herbs for weight loss Ephedrine and caffeine are the only herbs so far that have shown any promise as weight-loss drugs.

However, even if they do result in weight loss, there are still substantial risks. The big problem is that the botanical sources may contain too much or too little of either ingredient: caffeine and ephedra.

What's the harm? Caffeine, which is found in varying doses in beverages and medications, can cause insomnia and tremors, and acts as a diuretic (causing increased urination).

It is the most widely used "drug" in the world, thanks to tea and coffee lovers.

By itself, caffeine isn't harmful for most people.

However, when caffeine is teamed with ephedrine, it can speed up the heart (tachycardia), and heart attacks and strokes have been reported.

Other possible side effects include acute hepatitis, headache, tremor, nervousness and insomnia.

Combinations of ephedrine and caffeine have side effects substantially greater than those experienced from either compound alone.

Ephedra (Ma Huang)

The Chinese have used ephedra for more than 5,000 years. An extract of this powerful herb is ephedrine, one of the most effective treatments known for asthma, allergies, and sinus problems.

Ephedra is a central nervous system stimulator that can increase pulse rate and blood pressure. Reputable manufacturers will include a warning about this on the label. The main problem with ma huang is that many herbal manufacturers spike ephedra-containing weight loss products with caffeine, usually by adding herbs such as guarana seed or kola nut. Alone, caffeine can raise blood pressure and cause heart palpitations. When it is teamed with ephedra, the effects are magnified.

According to the Federal Drug Administration, since 1993 at least 17 people have died and 800 have been made sick by dietary supplements containing ephedrine.

Because of misuse and adverse reactions to products containing ephedrine, approximately 21 states have passed regulations that are stricter than the federal regulations. These include requiring that ephedrine products be made available only by prescription; moving ephedrine products to the list of controlled substances; and prohibiting weight loss, appetite control, or stimulant claims on the labels.

We strongly recommend that you not use ephedra-containing products.

Laxatives

First, and most importantly, laxatives do not really cause the loss of significant amounts of food or help in weight loss. They do cause dehydration and reflex fluid retention.

Therefore, laxative use is not an effective weight-control technique and can be dangerous.

A number of these herbs contain ingredients that act by irritating the lining of the intestines or by directly stimulating the nerves; over time and with over stimulation, the bowel becomes nonresponsive.

Laxatives often contain stimulants that can lead to stomach irritation, cramping, and loss of fluids and electrolytes.

What can you do?

If you buy herbs, how can you tell which have the highest quality and which products

really contain what the label claims?

There is no guarantee that the ingredients listed will match the actual contents, so remember that contamination, mislabeling, and misidentification can be problems.

Experts at the Mayo Clinic offer five tips for choosing the best brands of herbs:

1. Look for herbal extracts that are standardized. The United States Pharmacopoeia (USP) or National Formulary (NF) mark on the label or package is a clear sign that the manufacturer is following USP standards.

2. Choose a brand that adheres to higher manufacturing standards than are required. All herbal product manufacturers are supposed to follow standards established for processing foods; these are known as Good Manufacturing Practices.

Some companies set even higher standards for themselves, and usually will advertise this fact. Look for it in their ads.

3. Buy only single-herb products that clearly show how much is in each dose.

4. Beware of claims that sound too good to be true. Use your own common sense. No single herbal product can possibly take care of a wide number of ailments.

5. The FDA advises avoiding five dangerous herbs: belladonna, comfrey, broom, loblia, and pennyroyal. What to do if you have a bad reaction to a herbal product? If you become ill from taking an herbal remedy, call your doctor.

You or your doctor should also report the problem to the FDA.

Call 800-FDA-1088 or go to the FDA’s MedWatch Web site: www.fda.gov/medwatch.