Prescription weight loss medications, including GLP-1 agonists, orlistat, and setmelanotide, may be effective for some people. But other lifestyle changes are still necessary for long-term success.
If it’s challenging to lose weight despite making changes to your diet and increasing your physical activity, you may be wondering whether a prescription weight loss medication is right for you.
These medications tend to work via one or more of these mechanisms:
- reducing appetite, making you feel fuller, so you eat fewer calories
- reducing the absorption of nutrients, such as fat, making you take in fewer calories
- increasing fat burning, making you burn more calories
When paired with other lifestyle changes and taken under the supervision of a healthcare professional, these drugs may offer an effective way to lower your weight.
We reviewed all of the weight loss medications that are currently available, including how they work, who they might be appropriate for, research on their effectiveness, and potential safety concerns.
The Food and Drug Administration (FDA) has approved several drugs for losing weight with overweight and obesity. These medications require a prescription from a doctor and should only be taken under medical supervision.
- orlistat (Xenical)
- phentermine/topiramate (Qsymia)
- naltrexone/bupropion (Contrave)
- GLP-1 agonists, including liraglutide (Saxenda) and semaglutide (Wegovy)
- setmelanotide (Imcivree)
- appetite suppressants, including phentermine (Adipex-P or Lomaira)
These medications should be combined with a balanced weight loss diet, as alone, they’re not likely a helpful long-term solution for obesity and may lead to weight regain over time.
They also have many possible side effects, some of which can be serious.
Most weight loss medications are
- type 2 diabetes
- high blood pressure
- high cholesterol
Similarly, setmelanotide (Imcivree), is
These medications are designed for people who haven’t been able to achieve weight loss through other methods, including diet or lifestyle changes.
Though they shouldn’t be considered a quick fix, these medications can be a useful tool to support weight management when combined with regular physical activity and a nutritious diet.
Keep in mind that weight loss medications are not suitable for everyone, including people who are pregnant, those with certain health conditions, or individuals taking specific medications.
A healthcare professional can provide guidance on whether you might be a candidate for a prescription, depending on your personal goals, medical history, and health status.
Weight loss medications can be an effective tool to support weight management.
Most work by reducing your food intake, decreasing fat absorption, or increasing fat-burning, resulting in significant weight loss over time.
In most cases, these prescription medications can typically result in around
Keep in mind that these medications should be used alongside dietary changes and lifestyle modifications, such as regular physical activity.
Not only will adopting dietary and lifestyle changes help increase the effectiveness of weight loss drugs, they can help minimize weight regain, which often occurs after you stop taking these medications.
A quick look at prescription weight loss medications
1. Orlistat (Xenical)
Orlistat is an oral medication that’s available via prescription as Xenical. It can also be purchased over the counter as the brand Alli.
After a medical consultation, a doctor can prescribe orlistat. Certain telehealth services may also provide a prescription for this medication.
How it works: Orlistat works by blocking the activity of certain enzymes used to break down fats in the digestive tract, which
Effectiveness: According to a
Side effects: Orlistat often causes digestive issues like loose or oily stools, gas, and frequent bowel movements, making the medication difficult for some people to tolerate. It could also contribute to nutrient deficiencies, including in fat-soluble vitamins A, D, E, or K.
Following a low fat diet is typically recommended while taking this medication to help minimize adverse side effects.
Contraindications: chronic malabsorption, cholestasis (a type of liver disease), pregnancy, renal impairment, and current use of certain prescription medications.
Jargon-buster: “Contraindications” are any reason that someone shouldn’t take a specific medication.
2. Phentermine/topiramate (Qsymia)
Phentermine/topiramate is an oral medication that belongs to a class of drugs known as sympathomimetic amines. It requires a prescription from a doctor and is sold under the brand Qsymia.
How it works: This medication
Effectiveness: One research review concluded that phentermine/topiramate resulted in an average weight loss of
Another review comparing the effectiveness of several weight loss medications found that people with overweight or obesity who took phentermine/topiramate lost an average of
Side effects: The
It could also cause increased body temperature, an inability to sweat, and psychiatric or cognitive disturbances.
Contraindications: This medication is not recommended for people with glaucoma (eye conditions that can lead to blindness), a history of hyperthyroidism, pregnancy, recent use of monoamine oxidase inhibitors, and current use of certain prescription medications.
3. Naltrexone/bupropion (Contrave)
This medication, sold under the name Contrave, is an oral medication that
A doctor can determine whether Contrave may be a good option for you and then provide a prescription. Some online services may also prescribe Contrave following a virtual consultation with a healthcare professional.
How it works: Though the exact mechanism of naltrexone/bupropion isn’t fully understood, it’s believed to
Effectiveness: One review of four studies showed that naltrexone/bupropion was associated with significant weight loss compared with a placebo. Over 1 year, participants lost an average of
Another review had similar findings, reporting that naltrexone/bupropion
Side effects: Naltrexone/bupropion
Contraindications: This medication is not recommended for people with a history of seizures, end-stage renal disease, pregnancy, and current use of monoamine oxidase inhibitors, opioids, or certain other prescription medications.
4. GLP-1 agonists
Two GLP-1 agonists have been approved for weight loss, including liraglutide (Saxenda) and semaglutide (Wegovy). Both are available as a self-administered injection, but liraglutide is administered once daily, while semaglutide is only injected once per week.
Though not approved specifically for weight loss, some other GLP-1 agonists intended to treat type 2 diabetes are sometimes prescribed off-label for weight management,
- semaglutide (Ozempic or Rybelsus)
- dulaglutide (Trulicity)
- liraglutide (Victoza)
- exenatide (Byetta)
- exenatide extended-release (Bydureon BCise)
- tirzepatide (Mounjaro)
GLP-1 agonists are only available through a prescription from a doctor or other qualified healthcare professional. Several telehealth services and weight loss programs may also provide prescriptions if you meet the eligibility criteria, including Ro Body Program and Calibrate.
How it works: GLP-1 agonists work by
Effectiveness: Several studies have found that GLP-1 agonists could be beneficial for weight management.
For instance, one study in 1,961 adults found that taking 2.4 milligrams (mg) of semaglutide per week combined with lifestyle changes resulted in a
Another small study found that people taking liraglutide lost an average of
Side effects: Common side effects
Though uncommon, severe side effects have also been reported, which may require medical attention. These include kidney problems, thyroid C-cell tumors, gallbladder disease, low blood sugar, and suicidal ideation. It’s important to be in regular contact with your healthcare professional to monitor for these side effects.
More research is also needed on the long-term effects of these medications, as there’s concern about potential weight regain over time.
Contraindications: This medication is not recommended for people with multiple endocrine neoplasia (MEN) syndrome type 2, history of thyroid cancer or pancreatitis, pregnancy, and current use of certain prescription medications.
5. Setmelanotide (Imcivree)
Setmelanotide, sold as Imcivree, is in a class of medications known as melanocortin 4 (MC4) receptor agonists. It’s an injectable medication
How it works: People with specific genetic mutations may experience insufficient activation of the MC4 receptor in the brain, which could contribute to obesity.
Setmelanotide works by increasing the activation of this receptor, leading to reduced hunger, decreased calorie intake, and increased metabolism, all of which could promote weight loss.
Effectiveness: One study in 21 people taking setmelanotide found that
Another small study in children, adolescents, and adults
Side effects: Some of the most common side effects of setmelanotide include injection site reactions, hyperpigmentation, nausea, headache, diarrhea, and stomach or back pain. Fatigue, vomiting, and depression have also been reported.
Contraindications: This medication is not recommended for people with renal impairment, and those who are pregnant or breastfeeding.
6. Appetite suppressants
There are several anorectics, or appetite suppressants, available. However, phentermine (Adipex-P or Lomaira) is the most commonly prescribed.
Phentermine is taken orally and requires a prescription from a doctor or other healthcare professional.
How it works: These medications reduce appetite by
Effectiveness: One study in 3,411 people compared the effectiveness of several medications for obesity and found that people taking phentermine lost the highest percentage of body weight over 12 weeks. Those taking phentermine lost an average of
However, keep in mind that these medications are only recommended for short-term use, as you can build up a tolerance after several weeks, resulting in decreased effectiveness.
Side effects: Potential side effects may include nausea, vomiting, diarrhea, and stomach cramps.
Other severe side effects have been reported and require immediate medical attention, including shortness of breath, chest pain, and swelling of the lower extremities.
Contraindications: This medication is not recommended for people with a history of heart disease, hypertension, hyperthyroidism, glaucoma, diabetes, pregnancy, and certain prescription medications.