We have completed maintenance on DiscoverMagazine.com and action may be required on your account. Learn More

These 10 Weight Loss Drugs Like Ozempic Can Work, but Are They Safe?

Research has shown some benefits to different types of weight loss drugs. Here’s how they work — and the potential side effects to be aware of.

By Stephen C. GeorgeApr 30, 2024 1:00 PM
Weight Loss Pills Scattered from Bottle on Yellow Background
(Credit: Artem Stepanov/Shutterstock


Sign up for our email newsletter for the latest science news

If you’re concerned about getting back to or maintaining a healthy weight, the world is full of companies who are happy to lighten your wallet, at least, by selling you miracle drugs and supplements that they promise will help curb appetite, reduce fat, and cut weight. Unfortunately, far too many weight-loss aids and supplements are heavy on hype and light on evidence. That only adds to the frustration of people struggling with their weight — of whom there are many. According to the Centers for Disease Control and Prevention, nearly 74 percent of American adults are overweight. However, some medications have been shown to help people achieve and sustain a healthier weight. Most are available by prescription only and none are meant to replace a healthy diet and exercise plan. But for people who have been unable to control their weight through other means, these medications offer hope for a healthier life.

What Drugs Cause Weight Loss?

Diet and exercise are still two of the most important ways to maintain a healthy weight, but certain meds may help. (Credit: Kzenon/Shutterstock)

Not every weight-loss treatment is right for every person or every kind of weight-loss issue. Costs and dosages will vary depending on individual medical and insurance factors. It's always important to talk with your doctor about weight-loss goals and medical history to determine which treatment is right — and safe — for you.

1. Bupropion (Wellbutrin) and Bupropion-Naltrexone (Contrave)

Bupropion has been around for decades and was originally approved by the FDA in 1985 to treat depression. People who took bupropion reported greater energy and suppressed appetite, leading to the happy side effect of weight loss, which research confirmed.

Although the drug wasn’t approved for weight control, doctors began prescribing it off-label — the term for using an FDA-approved medication for a condition that the drug has not been approved specifically to treat.

However, in 2014, the FDA did approve Contrave, a medication that combines bupropion and naltrexone, a drug historically used to treat alcohol and drug addiction, but which also impacts parts of the brain that control appetite.

Side Effects of Bupropion

Although both drugs are generally well-tolerated, side effects of bupropion can include anxiety, irritability, restlessness, dry mouth, heart palpitations, trembling and trouble sleeping. In some cases, allergic skin reactions can occur, as well as severe headache and ringing of the ears.

In rare instances, seizures, confusion and other serious cognitive issues have been reported. Similar side effects have been reported with Contrave, as well as some digestive issues, such as nausea, vomiting and constipation.

Read More: A New Era for Obesity Treatment?

2. Dapagliflozin (Farxiga)

Another diabetes medication given the green light by the FDA in 2014, dapaliflozin was later approved to help patients suffering from heart failure and chronic kidney disease. Dapagliflozin improves blood sugar control by aiding the body in removing sugar (and the calories that come with it) from the bloodstream and through the kidneys via urine.

Research has shown that the drug has the added benefit of reducing fat mass, leading to weight reduction. As a result, some doctors have prescribed dapagliflozin as an off-label treatment for weight loss.

Side Effects of Dapagliflozin

Digestive issues including nausea, vomiting, and abdominal pain can occur, as can kidney issues, including changes in urination and bacterial infections of the urinary tract. Some people may be more prone to dehydration or yeast infections.

Diabetics in particular need to be careful of higher ketone levels in their blood and urine, which could be signs of a serious condition known as ketoacidosis

3. Liraglutide (Saxenda, Victoza)

This injectable drug was also originally approved to manage type-2 diabetes by lowering blood sugar levels (under the brand name Victoza). In 2014, the FDA approved the drug (under the name Saxenda) as a medication for chronic weight control.

Liraglutide has been shown to help regulate appetite, while also slowing gut action, making people feel fuller for longer. Digestive issues including nausea, vomiting, abdominal pain, and diarrhea can occur, in addition to headaches and fatigue. 

Read More: Forget Dieting. Here’s What Really Works to Lose Weight

4. MCT Oil

Refreshingly, MCT oil is not a prescription-only treatment, or even a drug. MCT stands for medium chain triglyceride. Simply put, MCT oil is a dietary supplement, widely available at pharmacies and grocery stores, that contains an easily digested form of fat believed to help boost energy and performance, while also helping to manage blood sugar levels and appetite.

Although a form of fat, MCT tends to be processed in the body more quickly than other forms of fat, and is less likely to be stored as fat in the body. Some research has indicated that using moderate amounts of MCT oil as a dietary supplement — perhaps one or two tablespoons per day — may help suppress appetite, promote feelings of fullness and so help maintain a healthy weight.

Side Effects of MCT Oil

MCT oil is, well, oily, and as such may be hard on some digestive systems. Gas, bloating, cramps, and diarrhea are all common side effects. And it is still a form of fat, which means that taking too much can cause weight gain and raise overall fat and cholesterol levels.

For this reason, people with heart conditions and liver problems should absolutely consult a doctor or nutrition expert before trying MCT oil.

Read More: What Factors Matter Most for Weight Loss?

5. Metformin (Glucophage, Fortamet)

One of the most widely prescribed drugs of its kind, metformin is yet another medication approved by the FDA for the treatment of type-2 diabetes. However, the drug is also often prescribed off-label to moderate weight loss. Like other drugs on this list, metformin is thought to help regulate appetite. It also appears to affect the gut microbiome in a manner that may improve metabolism and support weight loss.

Side Effects of Metformin

Generally considered safe and well-tolerated, some side effects of metformin may include stomach upset, as well as mild nausea or diarrhea.

In rare cases, some people may have an allergic reaction to the drug, or be at risk for a dangerous buildup of lactic acid in the bloodstream.

Read More: It Doesn't Take Long to Reset Your Gut Health With Small Lifestyle Changes

6. Orlistat (Alli, Xenical)

One of the few FDA-approved weight-loss drugs available in an over-the-counter strength (under the name Alli; Xenical is the prescription version), orlistat is known as a gastrointestinal lipase inhibitor, which means that it helps block your body’s absorption of fat normally consumed through food.

Generally intended to be taken with meals, orlistat has been shown to inhibit absorption of as much as 25 to 30 percent of the fat content in any given meal.

Research has shown that, when combined with a healthy diet and exercise regimen, orlistat can yield anywhere from 3 to 5 percent weight loss over the course of a few months.

Side Effects of Orlistat

The main side effects associated with orlistat are minor — at least from a medical perspective — but worth noting.

The pharmaceutical literature frames the problem delicately, stating simply that “changes in bowel function can occur.” To put it indelicately, if your body isn’t absorbing that fat, it’s getting rid of it in one of the fastest ways possible.

Oily stools, intestinal gas with oily and fecal discharge, and diarrhea of a surprising urgency are all distinct possibilities. Still, for people with significant weight issues, the risk is worth the reward.

Nevertheless, for obvious reasons, orlistat users are strongly advised to maintain low-fat diets while on the medication.

Read More: As Another Obesity-Fighting Drug Takes Center Stage, A Nutrition Expert Warns That Weight Loss Shouldn’t Be the Only Goal

7. Phentermine (Adipex-P) and Phentermine-Topiramate (Qysmia)

One of the oldest medications on this list (approved by the FDA in 1959), phentermine is also one of the most commonly prescribed drugs for weight loss. The drug is a stimulant, and is thought to help with weight by suppressing the appetite.

In 2012, a combination medication of phentermine and topiramate was approved for adult use by the FDA under the name Qysmia. Topiramate was originally approved for use in the treatment of epilepsy, but one of its noted side effects was that the medication seemed to cause weight reduction by suppressing the appetite.

It is also believed to reduce leptin levels in the body, which may additionally contribute to weight reduction.

Like other stimulants, phentermine can increase blood pressure and heart rate, and people who take it may feel restless, irritable, and have trouble sleeping. It is also a controlled substance and carries with it the risk of addiction.

People with heart conditions or a history of substance abuse should not take it without careful consultation with their doctor.

Topiramate side effects may include stomach upset, fatigue, dizziness, cognitive and emotional changes.

Read More: Why Do People Overeat and Is Obesity Genetic?

8. Semaglutide (Ozempic, Rybelsus, Wegovy)

This drug, available in injectable form but also as a pill, was originally approved in 2017 for diabetes. In 2021, a higher-dose form of the drug, branded as Wegovy, was approved by the FDA for weight management. Other forms of semaglutide, meanwhile, have been prescribed off-label for weight-loss treatment as well.

A New England Journal of Medicine study published in 2021 showed that a higher-dose version of the drug helped people in the study lose nearly 15 percent of their body weight on average in 68 weeks. In short order, the medication gained a kind of rock-star status, growing in demand so rapidly that there has been a shortage of the drug.

Semaglutide works by mimicking a hormone named “GLP-1” that tells the body that it’s full. It also slows digestion, so that those who take it feel fuller longer and so are less inclined to eat as much.

Stomach issues, including bloating, gassiness and constipation or diarrhea may occur. Dizziness and fatigue have also been reported.

Read More: Beyond Weight Loss and Diabetes, Ozempic Could Help Certain Heart Conditions

9. Setmelanotide (Imcivree)

This injectable drug was approved by the FDA in 2022, not as a general weight-loss drug, but for the treatment of severe obesity caused by a genetic mutation. For people who suffer from this rare mutation, setmelanotide activates neural pathways that help decrease appetite while also boosting the body’s metabolism, increasing the expenditure of energy. It’s not for everybody and should only be prescribed under the care of an endocrinologist.

Fatigue, mood swings, skin discoloration, and trouble concentrating or sleeping have all been reported as possible side effects.  

10. Tirzepatide (Zepbound, Mounjaro)

Under the name Zepbound, tirzepatide was approved by the FDA for weight-loss in 2023, while the version branded as Mounjaro is only FDA-approved for treatment of type-2 diabetes. But both are essentially the same drug, delivered as an injection.

Tirzepatide works similarly to semaglutide in that it also mimics a hormone in the body that regulates hunger, while additionally slowing down digestion and movement of food from stomach to small intestine.

As with many of the drugs listed here, gastrointestinal side effects may include indigestion, nausea, diarrhea or constipation, and other stomach complaints. Hair loss has also been reported by some users.

This article is not offering medical advice and should be used for informational purposes only.

Read More: Your Built-In Weight Loss System Works Like Wegovy, Ozempic and Mounjaro

Article Sources

Our writers at Discovermagazine.com use peer-reviewed studies and high quality sources for our articles, and our editors review for scientific accuracy and editorial standards. Review the sources used below for this article:

Before he became editor of Discover in 2012, Steve George spent more than 20 years as a writer and editor, specializing in health and medicine. He began his career at a scientific, technical and medical publisher, then moved to consumer-oriented publications, where his work has appeared in Men’s Health, Men’s Journal, Prevention, Outside and dozens of other magazines and web sites.

1 free article left
Want More? Get unlimited access for as low as $1.99/month

Already a subscriber?

Register or Log In

1 free articleSubscribe
Discover Magazine Logo
Want more?

Keep reading for as low as $1.99!


Already a subscriber?

Register or Log In

More From Discover
Recommendations From Our Store
Shop Now
Stay Curious
Our List

Sign up for our weekly science updates.

To The Magazine

Save up to 70% off the cover price when you subscribe to Discover magazine.

Copyright © 2024 Kalmbach Media Co.