The FDA has approved six prescription medications for long-term weight management, ranging from daily pills to weekly injections. They work through different mechanisms, produce different levels of weight loss, and come with different side effects. The newest injectable options have changed the landscape dramatically, but older oral medications remain effective alternatives for many people.
Who Qualifies for Weight Loss Medication
Weight loss medications are generally prescribed for adults with a BMI of 30 or higher, or a BMI of 27 or higher alongside a weight-related condition like type 2 diabetes, high blood pressure, or high cholesterol. Four of the six long-term medications are also approved for children ages 12 and older. These drugs are meant to be used alongside diet and exercise changes, not as replacements for them.
Weekly Injections: Wegovy and Zepbound
The two most effective weight loss medications currently available are both weekly injections. Wegovy (semaglutide) and Zepbound (tirzepatide) work by mimicking gut hormones that regulate appetite and blood sugar. They slow digestion, reduce hunger, and help your brain register fullness sooner. In clinical trials, these medications produced an average of 15 to 22% body weight reduction over one year, a level of weight loss that was previously only achievable through surgery.
Wegovy is approved for adults and children 12 and older. You start at a low dose and gradually increase over about four months to reach the full weekly dose of 2.4 mg. This slow ramp-up helps your body adjust and reduces the severity of side effects. Zepbound uses a similar gradual dosing schedule and is currently approved for adults only.
The most common side effects for both medications are gastrointestinal: nausea, constipation, and abdominal discomfort. These are a direct result of how the drugs work, since slowing gut movement is part of what suppresses appetite. For most people, these effects are worst during the first few weeks at each new dose level and improve over time. More serious but rare complications include pancreatitis (about 9 times higher risk compared to other weight loss drugs), bowel obstruction (about 4 times higher), and gastroparesis, a condition where the stomach empties too slowly (about 3.7 times higher), based on data from the American College of Gastroenterology.
Daily Injection: Saxenda
Saxenda (liraglutide) is an older daily injection that works through a similar mechanism to Wegovy but produces more modest weight loss. It targets the same appetite-regulating pathway but requires daily dosing instead of weekly. You start at 0.6 mg per day and increase weekly until reaching the maintenance dose of 3 mg daily after about five weeks.
Saxenda is approved for adults and children 12 and older. Its side effect profile is similar to the weekly injectables, with nausea and digestive discomfort being the most frequent complaints. For people who respond well to it, Saxenda remains a reasonable option, though many prescribers now favor the weekly injectables for their convenience and stronger results.
Oral Medications
Three pill-form options are approved for long-term use, and they work through entirely different mechanisms than the injectables.
Qsymia (Phentermine-Topiramate)
Qsymia combines an appetite suppressant with a medication originally used for seizures and migraines. It’s taken once daily and is approved for adults and children 12 and older. In clinical trials involving nearly 3,800 patients, people on the higher dose lost 24 to 32 pounds over 56 weeks, with noticeable results even at 12 weeks (15 to 19 pounds).
Qsymia carries some important safety concerns. It can cause birth defects, specifically cleft lip and cleft palate, so it should not be taken during pregnancy. Other potential side effects include increased heart rate, mood changes, trouble sleeping, concentration and memory difficulties, kidney stones, and decreased sweating that can lead to overheating. Stopping the medication abruptly can trigger seizures, so you need to taper off gradually.
Contrave (Naltrexone-Bupropion)
Contrave combines two existing medications: one used to treat alcohol and opioid dependence, and one used as an antidepressant. Together, they act on brain circuits involved in cravings and reward. It’s taken as a pill once or twice daily and is approved for adults only. Contrave produces moderate weight loss, generally less than the injectables or Qsymia, but it can be a practical choice for people who prefer oral medication and want to avoid injections.
Orlistat (Xenical and Alli)
Orlistat works completely differently from every other option on this list. Instead of acting on appetite or brain chemistry, it blocks about 30% of the dietary fat you eat from being absorbed in your gut. The unabsorbed fat passes through your digestive system, which is both the mechanism and the source of the medication’s most notable side effects: oily stools, gas, and urgent bowel movements, especially after high-fat meals.
Orlistat is the only weight loss medication available without a prescription, sold over the counter at a lower dose under the brand name Alli. The prescription-strength version (Xenical) is taken three times daily with meals. It’s approved for adults and children 12 and older. Weight loss with orlistat tends to be modest compared to newer options, but it appeals to people who want to avoid medications that affect the brain or hormones.
Short-Term Options
Phentermine, one of the oldest weight loss drugs, is FDA-approved only for short-term use of a few weeks. It works as a stimulant-type appetite suppressant. Doctors sometimes prescribe it as a starting point or bridge to other treatments, but it’s not designed for ongoing weight management. Because it can raise blood pressure and heart rate and carries a risk of dependence, it’s not appropriate for extended use.
Specialized Genetic Treatments
One additional medication, Imcivree (setmelanotide), exists in a category of its own. It’s approved only for people ages 6 and older who have obesity caused by one of three specific rare genetic conditions: POMC deficiency, PCSK1 deficiency, or leptin receptor deficiency. These conditions must be confirmed through genetic testing. Imcivree is not prescribed for general obesity, even when a genetic component is suspected, and it won’t work if the underlying genetic variant is classified as benign.
How to Think About Choosing
The right medication depends on several factors: how much weight you need to lose, whether you’re comfortable with injections, your other medical conditions, and what your insurance covers. The weekly injectables offer the most dramatic results but come with higher costs and gastrointestinal side effects that some people find hard to tolerate. Oral options produce more moderate weight loss but may be easier to access and afford.
Cost is a real barrier for many people. The newer injectables can run over $1,000 per month without insurance, and coverage varies widely between plans. Orlistat in its over-the-counter form is the most affordable option, though it’s also the least effective. Generic phentermine-topiramate and naltrexone-bupropion tend to fall somewhere in between.
One important consideration with all of these medications: weight tends to return after stopping them. Clinical data consistently shows that people regain a significant portion of lost weight within a year of discontinuing treatment, which is why these drugs are approved for long-term use rather than as short courses. The decision to start a weight loss medication is often a decision to stay on it indefinitely, and that’s worth factoring into your thinking from the beginning.