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Weight-Loss Medicines

About This Medicine

Make sure you know about each of the medicines you take. This includes why you take it, how to take it, what you can expect while you're taking it, and any warnings about the medicine.

The information provided here is general. So be sure to read the information that came with your medicine. If you have any questions or concerns, talk to your pharmacist or doctor.

What are some examples?

Here are some examples of medicines used for weight loss. Many are approved by the U.S. Food and Drug Administration (FDA) to treat obesity or overweight. Other medicines that may have the same ingredients are also used to help with weight loss.

  • Semaglutide (Wegovy, Ozempic). It may help you eat less. It's given as a shot or pill.
  • Liraglutide (Saxenda). This medicine may help you eat less. It's given as a shot once a day.
  • Tirzepatide (Zepbound). This medicine may help you eat less. You take this medicine as a shot once a week.
  • Phentermine/topiramate (Qsymia). This medicine combines the drugs phentermine and topiramate. Taking it once a day can help you eat less.
  • Bupropion/naltrexone (Contrave). This medicine may reduce your appetite. It may help you avoid overeating.
  • Orlistat (Xenical). Orlistat prevents some of the fat calories you eat from being absorbed in your intestines. It's also available without a prescription under the brand name Alli. Alli is half as strong as Xenical.

Why are prescription weight-loss medicines used?

Weight-loss medicines may be an option for people who have obesity or who are overweight and have weight-related health problems, such as high blood pressure or diabetes. These medicines may help some people who haven't been able to lose weight with diet and exercise.

How well do they work?

Different weight-loss medicines produce different results in each person. Many people are able to lose 5% to 16% or more of their body weight, depending on how they respond to the medicine.footnote 1 Your doctor can help you understand your options and decide what might be right for you.

Weight-loss medicines are used long-term along with healthy eating and being more active. Many people regain some or most of the weight they lost if they stop taking the medicines. If you stop taking the medicine, healthy eating and activity may help limit how much weight you gain back.

Weight loss medicines don't work for everyone. If you are having trouble reaching your goals, talk with your doctor about other things you can try.

What about side effects?

Many weight-loss medicines have side effects like nausea, vomiting, headaches, and changes in bowel habits. Some medicines are more likely to cause side effects than others. For example:

  • Blood pressure changes can occur with naltrexone-bupropion and semaglutide.
  • Changes in bowel habits can occur with orlistat. These changes may include oily or fatty stool and being unable to control bowel movements.

Sometimes the side effects are mild and go away over time. Tell your doctor about any side effects you have.

Your doctor will check whether weight loss improves any health conditions you have, such as type 2 diabetes, high cholesterol, and high blood pressure.

Before you get a prescription for weight-loss medicine, be sure to:

  • Tell your doctor if you're pregnant, breastfeeding, or planning to get pregnant. These medicines can harm a pregnancy or baby.
  • Tell your doctor about all prescription and over-the-counter medicines, vitamins, herbs, and supplements that you take.

General information about side effects

All medicines can cause side effects. Many people don't have side effects. And minor side effects sometimes go away after a while.

But sometimes side effects can be a problem or can be serious.

If you're having problems with side effects, talk to your doctor. Your doctor may be able to lower your dose or change to a different medicine.

Always be sure you get specific information on the medicine you're taking. For a full list of side effects, check the information that came with the medicine you're using. If you have questions, talk to your pharmacist or doctor.

What are some cautions about prescription weight-loss medicines?

The risks depend on which medicine you are taking. Risks are not common. Weight-loss medicine can harm a pregnancy or baby. Do not take these medicines if you're pregnant or breastfeeding.

General cautions for all medicines

Allergic reactions.
All medicines can cause a reaction. This can sometimes be an emergency. Before you take any new medicine, tell the doctor or pharmacist about any past allergic reactions you've had.
Drug interactions.
Sometimes one medicine may keep another medicine from working well. Or you may get a side effect you didn't expect. Medicines may also interact with certain foods or drinks, like grapefruit juice and alcohol. Some interactions can be dangerous.
Harm during pregnancy or breastfeeding.
If you are pregnant, trying to get pregnant, or breastfeeding, ask your doctor or pharmacist if all the medicines you take are safe.
Other health problems.
Before taking a medicine, be sure your doctor or pharmacist knows about all your health problems. The medicine for one health problem may affect another health problem.

Always tell your doctor or pharmacist about all the medicines you take. This includes prescription and over-the-counter medicines, vitamins, herbs, and supplements. That information will help prevent serious problems.

Always be sure you get specific information on the medicine you're taking. For a full list of warnings, check the information that came with the medicine you're using. If you have questions, talk to your pharmacist or doctor.

What should you know about cost?

Weight-loss medicines can range in cost. And they can be expensive. If you and your doctor have decided that you need a weight-loss medicine, you may want to know how much you will have to pay.

Some insurance companies may not pay for these medicines. If you have insurance, find out if it covers these medicines. Your insurance company may list this information on their website. If not, ask their customer service these questions:

  • Are weight-loss medicines covered? Which ones? For how long?
  • Do I need to use a certain drugstore?
  • What is my co-pay?

If you don't have insurance or it doesn't cover these medicines, talk to your doctor or pharmacist. They may be able to suggest patient-assistance programs, which help people pay for high-cost medicines. Or your doctor may be able to prescribe a different, lower-cost medicine.



  1. Drugs and devices for weight management. (2022). Medical Letter on Drugs and Therapeutics, 64(1651): 81–88a. Accessed July 12, 2023.


Current as of: May 13, 2023

Author: Healthwise Staff
Clinical Review Board
All Healthwise education is reviewed by a team that includes physicians, nurses, advanced practitioners, registered dieticians, and other healthcare professionals.