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Weight-loss medications


Several weight-loss medicines are available. Ask your health care provider if any are right for you. They should not be used unless you are overweight or obese. Each of them have some side effects. Your provider will consider your medical history when choosing to which medicine to prescribe.

These weight-loss drugs are used in people with a BMI over 30 or those with a BMI of 27 or higher with an obesity-related medical problem such as high blood pressure, diabetes, or high cholesterol. Unless noted, these medicines are only available by prescription.

You may lose about 5 to 10 pounds by taking these drugs. But not everyone loses weight while taking them. Most people also regain the weight after they stop taking the medicines, unless they have made lasting lifestyle changes, such as exercising and cutting unhealthy foods from their diets.

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. This includes prescription, herbal, and over-the-counter remedies. Over-the-counter refers to medicines, herbs, or supplements you can buy without a prescription.

ORLISTAT (Xenical and Alli)

Orlistat works by reducing your body's ability to absorb fatty foods. It can help you lose some weight, especially if you tend to eat more fatty foods. However, if you don't absorb the fat that you do eat, your body may pass this food as loose stools or diarrhea. The most unpleasant side effect of orlistat is oily diarrhea that may produce an urgency to have a bowel movement. Eating fewer fats can reduce this effect. So, despite this side effect, most people are able to tolerate this medicine.

Xenical is the brand of orlistat your provider can prescribe for you. You can also buy orlistat without a prescription under the name Alli.

PHENTERMINE (Ionamin, Adipex-P, Suprenza)

This medicine stimulates your brain and can reduce the feelings of hunger. It may make you more alert. It also can make you less interested in food. This medicine is available only by prescription.

Some side effects of phentermine are:

  • Dry mouth
  • Constipation 
  • Problems sleeping
  • Nervousness
  • Heart palpitations
  • Increase in blood pressure

PHENTERMINE combined with TOPIRAMATE (Qsymia)

This combination medicine was FDA approved in 2012. It reduces your appetite and helps you feel more satisfied with what you have eaten. Weight loss may be between about 7% to 9% of your body weight.

It should not be taken during pregnancy. Side effects include:

  • Increased heart rate
  • Constipation
  • Dry mouth
  • Dizziness
  • Numbness or tingling in feet, hands, arms or face
  • Change in the way foods taste
  • Insomnia

More serious side effects include:

  • Glaucoma
  • Trouble with concentration, memory and speech
  • Fever
  • Mood disorders such as depression or anxiety
  • Suicidal thoughts


This medication was also approved by the FDA in 2012. It works in your brain to control your appetite, and is usually taken twice a day.

Side effects can include:

  • Nausea
  • Dry mouth
  • Headache
  • Dizziness
  • Constipation
  • Tiredness
  • Fast or slow heart rate
  • Fever
  • Swelling in feet or hands
  • Mood changes such as depression or anxiety


This combination medication was FDA approved in 2014. It is a combination of bupropion, also known as Wellbutrin, and naltrexone, which is an anti-addiction medication. It also can reduce hunger and the cravings for food.

It can cause nausea, headache, insomnia, and increased blood pressure. It should not be taken during pregnancy. You should not take this medicine if you take a medicine called an MAO (monoamine oxidase) inhibitor.


This is a once a day injectable medication that was approved by the FDA in 2014. It is the same medication as Victoza, which is used for control of diabetes. Saxenda is a higher-strength dose of liraglutide, whereas Victoza is a lower dose. You may lose about 5% of your body weight.

Nausea is a more common side effect. This medicine also may cause pancreatitis, and it may cause thyroid tumors. It can lower blood sugar if it is high.

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

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

These 3 medicines are not approved by the FDA just to produce weight loss. So you should not take them if you do not have diabetes. Some other medications to treat diabetes can also produce unintended weight gain. You should ask your doctor about the diabetes medications that you take.

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Review Date: 1/30/2018

Reviewed By: John E. Meilahn, MD, Bariatric Surgery, Chestnut Hill Surgical Associates, Philadelphia, PA. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.

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