Anti-obesity medications are often used to help people who have tried and not been able to lose enough weight through exercise and dietary changes.

Obesity is a widespread issue affecting over 40% of adults living in the United States. However, many of them find it difficult to lose weight with exercise and reduced-calorie diets.

A growing number of effective anti-obesity medications can be used to treat obesity, often in combination with lifestyle and diet changes. Some of these medications started as treatments for type 2 diabetes but quickly gained favor for their ability to help people lose weight. They often work by affecting hormones in the brain and digestive system to reduce hunger and promote a sense of fullness.

The Food and Drug Administration (FDA) has approved several anti-obesity medications for chronic weight management. Learn more about the types available, as well as their benefits and side effects.

Phentermine-topiramate, sold under the brand name Qsymia, is available as an extended-release capsule that you take once daily. It is a combination of two medications that work to reduce your appetite and help you feel full.

Typically, you take it in conjunction with lifestyle measures, such as dietary changes and exercise. However, if you take this medication for 12 weeks and don’t lose a certain amount of weight, a doctor might recommend that you stop taking the medication.

Some of the more common side effects may include:

Naltrexone-bupropion comes in the form of an extended-release tablet to be taken once or twice daily.

Sold under the brand name Contrave, this medication combines bupropion, which is a type of antidepressant, and naltrexone, which is an opioid antagonist. Together, these medications help reduce appetite and cravings by influencing areas of the brain that control hunger.

Some possible mild side effects of this medication include:

  • vomiting or nausea
  • dizziness
  • dry mouth
  • headache
  • constipation

Liraglutide, sold under the brand name Saxenda, belongs to a class of medications called incretin mimetics. It’s a prescription medication given by injection once daily. Typically, people begin with a 0.6 milligram (mg) dose and increase the amount weekly until they reach a daily maintenance dose of 3 mg.

Experts also recommend eating a reduced-calorie diet and increasing the amount of regular exercise you get.

Liraglutide works by producing a hormone called glucagon-like peptide-1 (GLP-1) in the body, which regulates hunger. It also helps you feel full longer — making you less likely to eat more — by slowing the rate at which food moves through your digestive system.

Some possible side effects include:

The injectable medication semaglutide (Wegovy) is also a GLP-1 receptor agonist. It works by targeting parts of the brain that regulate appetite.

Like liraglutide, semaglutide is FDA approved at a higher dose for the treatment of obesity and at a lower dose for the management of type 2 diabetes.

People typically begin with a small weekly dose of 0.25 mg. Every 4 weeks, they increase their weekly dosage amount until they reach 1.7 mg or 2.4 mg for their maintenance dose.

Like liraglutide, semaglutide is usually not recommended for people with certain health conditions, such as pancreatitis, medullary thyroid cancer, or multiple endocrine neoplasia syndrome.

Zepbound (tirzepatide) is an injectable medication that was approved for the treatment of obesity, along with diet and exercise, after acquiring FDA approval as Mounjaro for the treatment of type 2 diabetes. Tirzepatide, which is a novel glucose-dependent insulinotropic polypeptide and GLP-1 agonist, reduces your appetite.

Like the other injectable medications, tirzepatide is administered weekly, and the dosage amount gradually increases. The maximum dosage amount is 15 mg weekly.

Like other anti-obesity medications, it can cause side effects, which can include

  • vomiting
  • diarrhea
  • nausea
  • constipation
  • stomach pain
  • fatigue
  • burping
  • hair loss
  • gastroesophageal reflux disease

Orlistat belongs to the category of medications known as lipase inhibitors. It comes in capsule form to be taken by mouth three times a day with food containing fat, usually at mealtime or up to 1 hour after eating. It’s available in both prescription (Xenical) and nonprescription (Alli) versions.

This medication works by reducing the amount of fat that the body absorbs from the food that you eat. However, it also interferes with the body’s ability to absorb beta-carotene and some fat-soluble vitamins. As a result, people who take orlistat may need to take a daily multivitamin containing beta-carotene, as well as vitamins A, D, E, and K.

You may also need to limit your fat consumption while taking Orlistat because extra fat can increase side effects. Side effects are most common in the first few weeks but can last longer.

Some of the more common side effects include:

  • gas with oily spotting
  • loose stools
  • urgent need to have a bowel movement
  • oily or fatty stools
  • more frequent bowel movements
  • stomach pain

Setmelanotide (Imcivree) is a type of medication known as a melanocortin-4 receptor agonist. It only has FDA approval for use in adults and children over 6 who are severely obese due to certain genetic conditions. The gene mutations must be confirmed by genetic testing.

This medication should be injected subcutaneously on a daily basis. People who don’t show any weight loss after several months may be encouraged by their doctor to discontinue the medication.

Typically, adults must meet one of these two criteria before a doctor will prescribe an anti-obesity medication:

  • a body mass index (BMI) of 30 or greater
  • a body mass index of 27 or greater, along with at least one weight-related health condition, such as type 2 diabetes or high blood pressure

According to 2022 guidelines from the American Gastroenterological Association, many anti-obesity medications are effective when taken alongside lifestyle measures. They are likely to help patients lose 5% and 10% of their total body weight, which can contribute favorably to their long-term health. The guidelines also suggested against using orlistat.

Which medication is best for obesity?

There in no single best medication for obesity. Instead, the best option can depend on individual needs and health status.

What is the most successful medication for weight loss?

Research has found that GLP-1 agonists are typically the most successful and effective medications for weight loss.

People today have many more options to help with obesity. If you are interested in trying an anti-obesity medication, talk with a doctor. GLP-1 drugs are becoming increasingly popular for their effectiveness, but a doctor can help you determine whether they are appropriate for you.