The FDA has approved seven different kinds of prescription medication for weight loss.
Tirzepatide (Mounjaro, Zepbound)
Tirzepatide belongs in the GLP-1 medication family. It keeps you feeling fuller for longer, slows digestion, and lowers appetite.
Mounjaro is the brand of tirzepatide medication prescribed to patients with diabetes, and Zepbound is the brand prescribed to those who are overweight or have obesity.
Tirzepatide is taken as a weekly injection. Your healthcare provider may teach you how to use it at home, or you can go to their office for injections, in which a small needle is inserted just under the skin in the fatty areas of your stomach, thighs, or upper arm.
In one meta-analysis, researchers found that people taking tirzepatide lost 21 more pounds than those who didn’t take it.
Serious side effects like low blood sugar are rare. More often, people report gastrointestinal symptoms like nausea, vomiting, and diarrhea. Between 40 and 50 percent of people on tirzepatide have these side effects, depending on their dosage.
Semaglutide (Ozempic, Wegovy, Rybelsus)
The popular injectable medications Ozempic and Wegovy belong to the semaglutide family. They are essentially the same medication, except Wegovy has a slightly higher maximum dosage.
These drugs work by prompting the release of insulin, which manages your blood sugar levels. It also slows down stomach emptying, which helps you feel fuller, longer.
Ozempic and Wegovy must be injected into fatty areas once a week. A meta-analysis of over 3,500 people found that those who injected semaglutide had almost 12 percent more weight loss than who took a placebo.
Smaller studies suggest that Rybelsus, which is semaglutide in pill form, may not offer the same level of weight loss.
Common side effects of semaglutide are pretty mild, says Primack. Most commonly, they include nausea, vomiting, and diarrhea. Constipation may also occur, but it is rare.
In some cases, more serious side effects may arise, such as:
- Stomach paralysis
- Upper stomach pain
- Swelling that makes it hard to breathe or swallow
- Rapid heartbeat
If you experience these symptoms, contact your healthcare provider right away.
Liraglutide (Victoza, Saxenda)
Liraglutide works similarly to semaglutide. It regulates blood sugar by releasing the right amount of insulin and also slows down stomach emptying.
With a full stomach, it’s easier to eat less, which helps you lose weight.
You have to inject liraglutide into fatty tissue once a day. This is more frequent than other options. A meta-analysis of 12 studies showed people taking liraglutide lost about seven pounds more than those who took a placebo.
Another analysis suggests that liraglutide may work less well than semaglutide.
Common side effects include moderate nausea and diarrhea. Other less common side effects include:
- Blood sugar changes
- Headache
- Heartburn
- Constipation
- Vomiting
- Stomach pain
- Increased feelings of depression
- Mood changes
Phentermine-Topiramate (Qsymia)
A combination of phentermine and topiramate, Qsymia works by decreasing appetite and making you feel fuller for longer.
Qsymia comes as an extended-release pill. You take it in the morning, and its contents slowly release throughout the day. According to a meta-analysis of six studies, phentermine-topiramate offered an average weight loss from almost 8 to 18 pounds, depending on the dosage.
The most common side effects of Qsymia include:
- Changes in taste
- Tingling, itching, burning, or prickling in your extremities
- Dry mouth
- Trouble staying focused
- Irritability
- Dizziness
- Constipation
- Numbness
- Headache
Naltrexone-Bupropion (Contrave)
Bupropion-naltrexone combines medications used for depression, quitting smoking, and substance and alcohol addiction.
These drugs work together within the brain to manipulate the brain’s hunger center and reward system, which helps control appetite and cravings.
Contrave comes as a capsule, and it usually follows an escalating schedule. That means you’ll take one pill in the morning for a week, then two a day the next week. After that, you may need to increase your dosage to two pills in the morning, then again at night. Your provider will give you details on your dose schedule.
A meta-analysis of 10 studies found people taking naltrexone-bupropion lost an average of 11 more pounds than those who took a placebo.
Most commonly, Contrave side effects include nausea and vomiting, constipation, and headache. Less often, people have reported dizziness and insomnia. More serious side effects include heart problems, thoughts of suicide, and seizures. Contrave’s manufacturers recommend keeping a low-fat diet around the time you take the medication to lessen your chance of seizures.
Orlistat (Xenical)
Orlistat prevents your intestines from absorbing some of the fat in the food you eat. Instead of being absorbed and stored by the body, the fat exits through your stool.
This medication comes in capsule form, which you take by mouth three times a day. You can take orlistat with each main meal that includes fat. Orlistat works well when taken during your meal or one hour afterward, but doses can be skipped with missed meals.
Orlistat’s weight loss benefits rank lower than the other options. In one large high-quality study of over 3,000 people, orlistat caused 2.4 percent weight loss after four years of taking it.
Most of orlistat’s side effects come from the retention of fats in your intestines. These include:
- Fatty stools
- Frequent bowel movements
- Gassiness
- Inability to hold in stool
You can avoid some of these effects by adding a fiber supplement to your diet.
Setmelanotide (Imcivree)
Setmelanotide belongs to a class of medications called melanocortin 4 (MC4) receptor agonists, which signal the brain to decrease appetite and increase metabolism.
This weight loss medication has only been approved by the FDA for people with certain genetic disorders.
Imcivree is not frequently prescribed, Primack says, because those genetic conditions are rare. “There are probably only a couple hundred people in the country who would need it,” Primack says. Taking setmelanotide typically involves an injection once every morning in the fatty areas of the stomach, thighs, or upper arms.
A small study found that 80 percent of people taking setmelanotide for severe obesity from one genetic disorder lost at least 10 percent of their body weight at the one-year mark, while 45 percent of those taking it for a different disorder lost 10 percent or more.
The most common side effects include nausea and skin reactions at the injection site.
Other, more serious side effects call for immediate medical attention. These include unexpected, frequent, or long-lasting erections for men and an increased libido for women.