Mayo Clinic Health Library

Over-the-counter weight-loss pills: Do they work?

Updated: 02-11-2012

The appeal of losing weight quickly is hard to resist. But do weight-loss pills and products lighten anything but your wallet? And are they a safe option for weight loss? Here's a look at some over-the-counter weight-loss pills and what they will and won't do for you.

Over-the-counter doesn't mean risk-free

A number of weight-loss pills are available at your local drugstore, supermarket or health food store. Even more options are available online. Most haven't been proved effective, and some may be downright dangerous.

Dietary supplements and weight-loss aids aren't subject to the same rigorous standards as are prescription drugs. Thus, they can be sold with limited proof of effectiveness or safety. Once a product is on the market, however, the Food and Drug Administration (FDA) monitors its safety and can take action to ban or recall dangerous products. Indeed, the FDA has banned the sale of supplements containing ephedra and other ephedrine-like ingredients.

Check the facts before you buy

It's important to do your homework if you're thinking about trying over-the-counter weight-loss pills. Read labels and talk with your doctor or pharmacist. Also be sure to check the FDA website for alerts about safety concerns and product recalls.

The table shows common weight-loss pills and what the research shows about their effectiveness and safety.

ProductClaimEffectivenessSide effects
Alli — OTC version of prescription drug orlistat (Xenical) Decreases absorption of dietary fat Effective; but weight loss is even more modest than that with Xenical Loose stools, oily spotting, frequent or hard-to-control bowel movements; reports of rare, but serious liver injury
Bitter orange Increases calories burned Probably ineffective Similar to ephedra: raised blood pressure and heart rate
Chitosan Blocks absorption of dietary fat Probably ineffective Uncommon: upset stomach, nausea, gas, increased stool bulk, constipation
Chromium Decreases appetite and increases calories burned Probably ineffective Uncommon: headache, insomnia, irritability, mood changes, cognitive dysfunction
Conjugated linoleic acid Reduces body fat Possibly effective Upset stomach, nausea, loose stools
Green tea extract Decreases appetite, and increases calorie and fat metabolism Insufficient evidence to evaluate Dizziness, insomnia, agitation, nausea, vomiting, bloating, gas, diarrhea
Guar gum Blocks absorption of dietary fat and increases feeling of fullness Possibly ineffective Abdominal pain, gas, diarrhea
Hoodia Decreases appetite Insufficient evidence to evaluate Insufficient information available
Sources: U.S. Food and Drug Administration, 2011; Natural Medicines Comprehensive Database, 2011

Include your doctor in your weight-loss plans

If you're considering trying weight-loss pills, be sure to talk with your doctor, especially if you have health problems or take prescription drugs. Your doctor can provide support and advice on losing weight and can monitor your progress. Just as important, your doctor can talk with you about possible side effects and what to watch out for.

In addition, your doctor can help determine if weight-loss pills are likely to interact with any prescription drugs you take. Many weight-loss pills contain multiple ingredients, such as herbs, botanicals, vitamins, minerals, and even caffeine or laxatives. If you take prescription drugs — or herbal or dietary supplements — adding weight-loss pills to the mix can be tricky.

Despite the hype, no quick fixes

The makers of weight-loss pills would like you to believe that their products will miraculously solve your weight problems. But keep in mind that even if you take a weight-loss pill, you still have to eat fewer calories than your body uses in order to lose weight. And even if these products help you lose weight initially, you will probably have to keep taking them to keep the weight off, which may not be practical or safe.

The reality is that there's no magic bullet for losing weight. The most effective way to lose weight and keep it off is through lifestyle changes: Eat healthy, low-calorie foods, watch portion sizes and be physically active. It's not magic, but it works.

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