Weight-loss medications


Several weight-loss medicines are available. Ask your health care provider if any are right for you.

About 5 to 10 pounds can be lost by taking these medicines. But not everyone loses weight while taking them. Most people also regain the weight after they stop taking them, unless they have made lasting lifestyle changes, such as exercising and cutting unhealthy foods from their diet.

You may also see ads for herbal remedies and supplements  that claim to help you lose weight. But many of these claims are not true. Some of these supplements can have serious side effects.

Note for women: Pregnant or nursing women should never take diet medicines of any kind. This includes prescription, herbal, and other over-the-counter remedies. Over-the-counter refers to medicines, herbs, or supplements you can buy without a prescription.

Medicine Options


About 6 pounds can be lost when using this drug. But not everyone loses weight while taking it. Many people regain most of this weight within 2 years after stopping the drug.

The most unpleasant side effect of orlistat is oily diarrhea, which may leak from the anus. Eating fewer fats can reduce this effect. Even with these side effects, most patients are able to tolerate this medicine.

Xenical is the brand of orlistat that your health care provider can prescribe for you. You can also buy orlistat without a prescription under the name Alli. These pills are half the strength of Xenical. They will cost about $100 a month, or more. Consider whether the cost, side effects, and small weight loss you can expect are worth it to you.

Your body may not absorb important vitamins, minerals, and other nutrients from food while you are using orlistat. You should take a daily multivitamin supplement if you take this drug.


These medicines stimulate your brain. This means they will make you more alert and wakeful. They also make you less interested in food.

Some of these stimulants are approved for treating obesity. The average weight loss while taking these drugs is about 5.8 pounds. But not everyone loses weight while taking them. Most people regain the weight after they stop taking the drug, unless they have made lasting lifestyle changes.

These medicines are available only by prescription. They include:

  • Phentermine (Ionamin, Adipex-P, Fastin)
  • Phentermine combined with topiramate (Qsymia)
  • Benzphetamine (Didrex)
  • Phendimetrazine (Adipost, Bontril, Melfiat, Plegine, Prelu-2, and Statobex)
  • Diethylpropion (Tenuate)

Phentermine is the most commonly prescribed of these drugs. It costs less than orlistat. But  like orlistat, its effects do not last long. Some side effects of phentermine are:

  • Increase in blood pressure
  • Problems sleeping, nervousness, palpitations, dry mouth, and constipation
  • Depression, which many people who are obese struggle with already

Note: If you have diabetes that needs treatment with medicines, you may want to ask your doctor about diabetes medicines that can contribute to weight-loss. These include:

  • Exenatide (Byetta)
  • Liraglutide (Victoza)
  • Metformin (Glucophage, Glumetza, and Fortamet)

These medicines are not approved by the FDA to "treat weight-loss". So you should NOT take them if you do not have diabetes.


Jensen MD. Obesity. In: Goldman L, Schafer AI, eds. . 24th ed. Philadelphia, PA: Elsevier Saunders; 2011:chap 227.

Rockville, MD. US Preventive Services Task Force; June 2012: AHRQ publication 11-05159-EF-2.


    Encyclopedia content is provided as information only and not intended to replace the advice and instruction from your personal physician.