While you probably know that the safest and most effective way to lose weight permanently is to eat less and exercise more, Americans have an obsession with rapid results. As a consequence, diet pills are a big business for manufacturers. Some, however, are very unsafe, and have been linked to kidney problems and damage.
Ephedra was once a common ingredient in diet pills because it increases your metabolic rate and causes you to burn more calories than you otherwise would. However, among the side effects of ephedra, it's known to cause kidney stones, explains the National Institutes of Health. Because it's been shown to be dangerous, it's been banned in the United States. However, manufacturers of diet pills work hard to find ways to modify molecules like ephedra, producing similar -- but not yet banned -- molecules with similar effects, and similar side effects.
While the FDA works hard to ensure that drugs are safe before they are released to the market, there's tremendous pressure on the FDA to release promising new drugs quickly so that manufacturers can benefit from them. Sometimes, this means that a drug makes it to market before a damaging side effect is discovered. For instance, "The Globe And Mail" -- a Canadian news website -- reported on research at the University of Western Ontario that said the diet drug orlistat, sold under the brand name Xenical, was linked to increased risk of kidney damage. While it's still available, health-care workers must closely monitor patients using this diet drug.
There's a public perception that herbs and other alternative remedies are safer than pharmaceutical drugs. However, just because a substance is natural doesn't mean it's safe -- some of the most toxic substances known occur naturally. For instance, aristolochia, a Chinese herb once used in various applications including diet pills, causes the kidneys to shut down. The website HealthWise reports that diet pills containing aristolochia, though now banned, resulted in kidney destruction in multiple patients.
If you are looking to lose weight, the best thing is to talk to your doctor for guidelines on how to do so in a healthy manner. If you're otherwise healthy, it's probably safe to reduce your food intake slightly, or to increase your exercise. However, you should always check with your doctor before taking any diet pill, regardless of whether it's prescription, over-the-counter, or herbal. Doing otherwise could risk the health of your kidneys.