Excess weight requires lifelong management. Weight issues are progressive as we age, and frequently excess weight returns. Obesity is a chronic condition that places your health at risk, however, there are various options for managing and treating excess weight. Prescription weight loss drugs are now considered a frontline treatment. Your weight is classified as obese if your body mass index (BMI) is 30 or higher.
Doctors will prescribe them if you meet this criterion or if it's at least 27 and you have a condition that may be related to your weight, like type 2 diabetes or high blood pressure.
You'll still need to focus on diet and exercise while taking these drugs, and they're not for everyone.
The medication semaglutide (Wegovy) received FDA approval for the treatment of obesity in 2021. More common prescription weight loss drugs which have been in use longer include liraglutide (Saxenda), naltrexone-bupropion (Contrave), orlistat (Alli, Xenical), and phentermine-topiramate (Qsymia).
Before you get a weight loss drug prescription, tell your doctor about your medical history. That includes any allergies or other conditions you have; medicines or supplements you take (even if they're herbal or natural); and whether you're pregnant, breastfeeding, or planning to get pregnant soon.
Liraglutide (Saxenda)
How it works: Liraglutide is the same drug as the type 2 diabetes drugs Sadenxa and Victoza. It mimics an intestinal hormone that tells the brain your stomach is full.
Approved for long-term use? Yes.
Side effects: Nausea, vomiting, diarrhea, constipation, and low blood pressure. Serious side effects can include raised heart rate, pancreatitis, gallbladder disease, kidney problems, and suicidal thoughts. Liraglutide has been shown in studies to cause thyroid tumors in animals, but it is not yet known if it can cause thyroid cancer in humans.
What else you should know: If you don't lose 4% of your weight after 16 weeks of taking Liraglutide, your doctor may tell you to stop taking it, because it's unlikely to work for you, the FDA says.
Tirzepatide (Mounjaro)
How it works: Mounjaro is a first-in-class medicine that activates both the hormones GLP-1 and GIP receptors and leads to improved blood sugar control. During tirzepatide diabetes trials, researchers noted people who got tirzepatide lost much more weight than those on standard diabetes therapy.
Approved for long-term use? Not FDA-approved for weight loss but used to treat obesity off-label.
Side effects: Nausea, vomiting, diarrhea, decreased appetite, constipation, upper abdominal discomfort, and abdominal pain.
What else you should know:
This medication is administered by injection under the skin once weekly.
Naltrexone HCl and bupropion (Contrave)
How it works: Contrave is a combination of two FDA-approved drugs, naltrexone, and bupropion, in an extended-release formula. Naltrexone is approved to treat alcohol and opioid dependence. Bupropion is approved to treat depression, and seasonal affective disorder, and help people stop smoking.
Approved for long-term use? Yes.
Side effects: The most common side effects include nausea, constipation, headache, vomiting, dizziness,insomnia, and dry mouth. Contrave has a boxed warning about the increased risk of suicidal thoughts and behaviors associated with bupropion. The warning also notes that serious neuropsychiatric issues linked to bupropion have been reported. Contrave can cause seizures and must not be used in patients who have seizure disorders. The drug can also increase blood pressure and heart rate.
What else you should know: If you don't lose 5% of your weight after 12 weeks of taking Contrave, your doctor may tell you to stop taking it, because it's unlikely to work for you, the FDA says. Taken together they appear to signal the brain to decrease food intake.
Orlistat (Xenical)
How it works: Blocks your body from absorbing about a third of the fat you eat.
When a doctor prescribes orlistat, it's called Xenical. If you get it without a prescription, it's called Alli, which has half of Xenical's dose.
Approved for long-term use? Yes.
Side effects include abdominal cramping, passing gas, leaking oily stool, having more bowel movements, and not being able to control bowel movements.
These side effects are generally mild and temporary. But they may get worse if you eat high-fat foods.
Rare cases of severe liver injury have been reported in people taking orlistat, but it's not certain that the drug caused those problems.
What else you should know: You should be on a low-fat diet (less than 30% of your daily calories from fat) before taking orlistat.
Also, take a multivitamin at least 2 hours before or after taking orlistat, because the drug temporarily makes it harder for your body to absorb vitamins A, D, E, and K.
Orlistat is the only drug of its kind that's approved in the U.S. All other prescription weight loss drugs curb your appetite, including the following.
Phentermine
How it works: Curbs your appetite.
Your doctor may prescribe this under the names including Adipex or Suprenza.
Approved for long-term use? No. It's approved for short-term use (a few weeks) only.
Side effects can be serious, such as raising your blood pressure or causing heart palpitations, restlessness, dizziness, tremor, insomnia, shortness of breath, chest pain, and trouble doing activities you've been able to do. Less serious side effects include dry mouth, unpleasant taste, diarrhea, constipation, and vomiting.
As with some other appetite suppressants, there's a risk of becoming dependent upon the drug.
Don't take it late in the evening, as it may cause insomnia.
If you take insulin for diabetes, let your doctor know before you take phentermine, as you may need to adjust your insulin dose.
You should not take phentermine if you have a history of heart disease, stroke, congestive heart failure, or uncontrolled high blood pressure. You also shouldn't take it if you have glaucoma, hyperthyroidism, or a history of drug abuse, or if you are pregnant or nursing.
What else you should know: Phentermine is an amphetamine. Because of the risk of addiction or abuse, such stimulant drugs are "controlled substances," which means they need a special type of prescription. Other drugs similar to phentermine that may be an option include benzphetamine, diethylpropion, and phendimetrazine.
Phentermine and topiramate (Qsymia)
How it works: Curbs your appetite.
Qsymia combines phentermine with the seizure/migraine drug topiramate. Topiramate causes weight loss in several ways, including helping you feel full, making foods taste less appealing, and burning more calories.
Approved for long-term use? Yes. Qsymia has much lower amounts of phentermine and topiramate than when these drugs are given alone.
Side effects: The most common side effects are tingling hands and feet, dizziness, altered sense of taste, insomnia, constipation, and dry mouth.
Serious side effects include certain birth defects (cleft lip and cleft palate), faster heart rate, suicidal thoughts or actions, and eye problems that could lead to permanent vision loss if not treated.
Women who might become pregnant should get a pregnancy test before taking Qsymia, and should use birth control and get monthly pregnancy tests while on the drug.
You also shouldn't take Qsymia if you have glaucoma, hyperthyroidism, heart disease, or stroke. Get regular checks of your heart when starting the drug or increasing the dose.
What else you should know: If you don't lose at least 3% of your weightafter 12 weeks on Qsymia, the FDA recommends that you stop taking it or that your doctor increase your dose for the next 12 weeks -- and if that doesn't work, you should gradually stop taking it.
Semaglutide (Wegovy)
How it works:Semaglutide working by imitating an intestinal hormone that stimulates insulin production, lowering your appetite and making you feel full
Semaglutide was initially approved as a treatment of type 2 diabetes and is prescribed for that use under the names Ozempic and Rybelsus. As Wegovy, it is specifically for treatment of obesity.
Approved for long-term use? Yes.
Side effects include abdominal cramping, constipation, vomiting, passing gas, headache, fatigue, and gastro reflux.
These side effects are generally mild and temporary.
In rare cases, issues involving the kidney as well as blurred vision have occurred. Semaglutide has been linked with instances of disease of the pancreas (pancreatitis). Get medical help right away if you develop symptoms of pancreatitis, including severe stomach/abdominal pain, nausea/vomiting that doesn't stop.
What else you should know: Indications are that you would need to take semaglutide for life to manage your weight. Ceasing to take it could lead to regaining most of the lost weight.
You should also follow a low-calorie diet and exercise program.