Weight Loss Medications

Weight loss medications help you lose weight. Some work by helping you feel less hungry and fuller. Others work by changing how you absorb fat or burn calories. Many weight loss drugs are injections, but some are pills you swallow.

Losing weight isn’t always as simple as eating less and exercising more. These drugs can be the answer to years of health challenges for many people. But they aren’t a quick fix or a silver bullet. They come with risks and side effects. And they aren’t for everyone.

Your healthcare provider can help you understand the pros and cons of this treatment and if it’s right for you. Weight loss medicines should always be taken under your provider’s supervision.

Who should take weight loss drugs?

These drugs are for people who have health conditions stemming from obesity or overweight. These conditions could include:

• Heart disease
• High cholesterol
• High blood pressure
• Sleep apnea
• Type 2 diabetes
• Fatty liver disease
• Joint pain
• Being unable to have surgery due to weight

Healthcare providers also use body mass index (BMI) as a factor. They may suggest weight loss medication if:

• You’re an adult with a BMI of 30 or higher
• You’re an adult with a BMI higher than 27, plus a weight-related health condition

The decision to begin weight loss drugs should only happen after you and your provider discuss your health history.

How do weight loss medications work?

Weight loss drugs work in different ways to help you lose weight. Most of them work in one or more of the following ways: 

• Decrease your appetite or reduce cravings
• Help you feel full
• Change how you absorb fat
• Increase how many calories you burn
• Improve insulin sensitivity 
• Acting on the “weight set point” in the brain and lowering it

Most weight loss medicines are prescription only. They’re broadly classified by the way they work. They can also be categorized as being a GLP-1 agonist or not. This is a newer class of medications that were first used to treat Type 2 diabetes. Healthcare providers noticed that it also led to significant weight loss. Because of this, some GLP-1s are now approved for weight loss, too.

List of FDA-approved weight loss drugs

These are FDA-approved for weight management for adults as of 2025:

• Bupropion/naltrexone (Contrave^®)
• Liraglutide (Saxenda^®)
• Orlistat (Alli^®, Xenical^®)
• Phentermine/topiramate (Qsymia^®)
• Phentermine (Adipex-P^®)
• Semaglutide (Wegovy^®)
• Tirzepatide ( Zepbound^®)

Bupropion/naltrexone

Bupropion-naltrexone combines an antidepressant (bupropion) and an addiction treatment drug (naltrexone). It comes as a pill that you swallow. It works by changing your brain chemistry, so you aren’t hungry. It can raise blood pressure, so your provider will need to check yours regularly. Common side effects include nausea, headache and constipation. Bupropion also carries a suicide risk warning. This medication is also helpful if you have substance use disorder or if your main issue is sugar cravings.

Liraglutide

This medication slows down how quickly your stomach empties. This makes you feel fuller for longer. Liraglutide is a daily injection. Nausea is the most common side effect.

Orlistat

Orlistat works by changing how your body digests and absorbs fat. A lower-dose version of orlistat (Alli) is available over the counter. It may cause side effects like gas and diarrhea. It works best when you follow a low-fat diet. These weight loss medications come in a pill you swallow.

Phentermine/topiramate

This combination drug helps with weight loss by decreasing your appetite and helping you burn calories. Possible side effects include increased heart rate and blood pressure, insomnia and nervousness. Phentermine as a standalone weight loss medication (Adipex-P) is for short-term use only. This medication comes as a pill you swallow. Topiramate can cause kidney stones.

Semaglutide

This medication can also help with Type 2 diabetes because it helps manage blood sugar levels. It also helps you feel fuller for longer. It’s a weekly injection. Side effects could include stomach issues like diarrhea, vomiting and nausea.

Tirzepatide

This drug lowers blood sugar and reduces appetite by working with two natural hormones (GLP-1 and GIP) in your body. Tirzepatide helps you feel full longer, so you eat less. It’s a once-weekly injection. Common side effects include nausea, diarrhea and vomiting.

Are there any over-the-counter weight loss medicines?

Alli is the only one that’s FDA‑approved and available over the counter (OTC). Other OTC weight loss medications are supplements. They aren’t as powerful or as well-studied as prescription weight loss medications. Talk to your healthcare provider before buying weight loss supplements on your own.

What are the side effects of weight loss medicine?

It’s important to know the side effects of this medication before starting it. Common side effects are:

• Digestive issues like nausea, stomach cramps, diarrhea and vomiting
• Headaches or dizziness
• Mood changes

More serious side effects can include:

• Kidney injury/stones
• Pancreatitis
• Gallstones
• Vision loss
• Intestinal obstruction

Risks

There are some risks involved with taking these drugs. They include:

• Long-term safety: Some of these drugs are newer and haven’t been studied for years of use. Experts aren’t totally sure if they’re safe to use for several years or how they’ll affect you later in life.
• Nutrient absorption issues: You may be deficient in vitamins A, D, E and K if you use drugs that block fat absorption. Providers recommend taking a multivitamin.
• Potential to regain weight: There’s a high chance that you’ll gain weight back when you stop taking the medication, especially if you don’t make lifestyle changes.
• Drug interactions: Always be sure to tell your provider about any medications you take or if you begin a new medication.
• Harmful during pregnancy: You should never take weight loss drugs if you’re pregnant, trying to get pregnant or breastfeeding.
• Costly: Some drugs are expensive because they aren’t covered by insurance.

Weight loss medications are relatively new. Healthcare researchers are still studying the long-term risks and effects.

What are the benefits of weight loss medicines?

The main benefit is that it helps you lose weight. This can improve your overall health and reduce your risk of developing obesity-related conditions like heart disease. Other benefits include:

• Lower blood pressure, cholesterol and blood sugar
• Easier movement and less joint/muscle pain
• More confidence in your body

How effective are weight loss medications?

Most adults can expect to lose between 3% to 12% of their starting body weight after one year.

Their exact success varies depending on factors like:

• The medication and your individual response
• How long you use it
• If you eat healthy and exercise while taking it

Results can vary from person to person. The weight can come back if you stop the medication. That’s why developing healthy eating and exercise habits should be part of your treatment plan, too.

How long will I take weight loss medication?

It depends on your results and side effects. If you’re doing well on the medicine, your provider may suggest you stay on it for years. But if you aren’t seeing results or having serious side effects, they may recommend you stop, switch or add medication.

How long until I see results from weight loss drugs?

This varies. Most people lose around 5% of their body weight after three to six months. If you don’t, your provider may suggest a different medication or add another medication. You should also make sure you check in with your provider regularly so they can monitor your progress.

When should I call my healthcare provider?

You should only use weight loss drugs if you plan on keeping regular checkups with your healthcare provider. They’ll need to monitor your weight loss and make sure it’s still safe for you to take the medication.

Contact your provider right away if you have any of the following symptoms:

• Serious side effects like chest pain, trouble breathing or a fast heartbeat
• Mood changes like depression, anxiety or suicidal thoughts
• Intense or severe stomach issues like vomiting constantly or being nauseous all the time
• Any other new symptoms or health problems