Appetite Suppressants: What You Should Know

Medically Reviewed by Jennifer Robinson, MD on April 18, 2022
3 min read

It's normal to feel hungry. It's your body's way of telling you it's time to fuel up. But if you find yourself craving food even though you just ate, there's a good chance you'll gain weight. Can appetite suppressants help?

Maybe. But before you consider trying them, take some time to learn what they are and how they work.

Appetite suppressants are drugs designed to curb hunger and, in turn, help you lose weight. The FDA has approved these medications that you can only get with a doctor's prescription:

Liraglutide (Saxenda). You take this as an injection. It was also marketed as a diabetes treatment under the brand name Victoza. The drug dampens hunger by acting on a hormone in the gut.

Naltrexone/bupropion (Contrave). It contains two medications and may affect the reward system in your brain, so eating certain foods that would normally make you feel good no longer do. It also works on the hypothalamus, the part of your brain that regulates appetite, temperature, and other functions.

Phentermine/topiramate (Qsymia). It's a combo of two drugs. Phentermine is a stimulant that makes you feel less hungry. Topiramate is a medicine used for seizures and headache, but as part of a combo with phentermine may make you feel less hungry and more full.

There are also some other options -- like phentermine, benzphetamine, diethylpropion, and phendimetrazine -- but those can only be used for up to 12 weeks.

You may have heard of another drug the FDA has approved to treat obesity called orlistat (Alli), but it's not an appetite suppressant. It works by preventing your body from absorbing a portion of fat from the food you eat. The brand name of the prescription-strength version is called Xenical.

There are also supplements that claim to be appetite suppressants. These products, though, aren't classified as drugs by the FDA, so they're not reviewed by the agency before they hit the market. There aren't any over-the-counter appetite suppressant drugs that have been approved by the FDA.

Yes, but probably not as much as you might hope. A review of studies on five major FDA-approved prescription medications for obesity, including orlistat, shows that any of them work better than a placebo for helping people lose at least 5% of their body weight over the course of a year. Phentermine-topiramate and liraglutide had the highest odds of making that happen.

For some perspective, that means a person who started at 200 pounds would have a good shot of losing at least 10 pounds with one of these drugs. Of course, some people lose a lot more weight, but others lose less.

It's also important to understand that these drugs don't work on their own. Studies show that weight loss medication, including appetite suppressants, work best when you're also making healthy changes to your eating and exercise habits at the same time.

Weight loss medication isn't for everyone, so talk to your doctor. They might encourage you to try other things, including making changes to your diet, exercise, and sleep habits.

They may also suggest you manage any emotional issues before you try an appetite suppressant. But if lifestyle changes haven't worked and your BMI is at least 30 (or at least 27 and you also have a weight-related health issue like high blood pressure), then a medication might be in order.

As with any medication, appetite suppressants sometimes cause side effects, which may include:

  • Dizziness
  • Insomnia
  • Nervousness
  • Digestive problems like nausea, constipation, diarrhea, and stomach pain

Side effects are usually mild, though not always, and some experts believe the risks aren't worth it. One appetite suppressant, liraglutide, has caused thyroid cancer in studies done on animals, though it's not known if it causes that disease in people.

If you do decide to try an appetite suppressant, tell your doctor if you have any side effects from it.