Weight-loss medications, compared
Every FDA-approved weight-loss drug in one place — the injections and the pills — with what each is really approved for, the average weight loss its trial reported, the main safety warning, and our independent FDA recall-safety rating. We rate medications on their safety record; we don’t sell them or prescribe them.
The one thing that confuses everyone
Ozempic and Mounjaro are diabetes drugs, not weight-loss drugs — using them to lose weight is off-label. Their exact same molecules are FDA-approved for weight, under different brands and doses: semaglutide is Ozempic (diabetes) and Wegovy (weight); tirzepatide is Mounjaro (diabetes) and Zepbound (weight). The weight-approved brands are the ones studied and dosed for it.
Weight-loss injections
The GLP-1 and GIP/GLP-1 injectables — the drugs behind the biggest average weight loss in trials, and the most-searched category. Ranked by our recall-safety score.
Wegovy (semaglutide)
The same molecule (semaglutide) is also sold as Ozempic (once-weekly injection, for type 2 diabetes) and Rybelsus (daily oral tablet, for type 2 diabetes).
- How it’s taken
- A once-weekly subcutaneous injection (titrated over 16 weeks to the 2.4 mg maintenance dose); a once-daily 25 mg oral tablet form is also approved.
- Approved for
- FDA-approved for chronic weight management — to reduce excess body weight and maintain weight reduction long term in adults and children 12+ with obesity, or adults who are overweight with a weight-related condition; also approved to cut the risk of major cardiovascular events in adults with established CV disease plus obesity/overweight.
- Average weight loss
- In the pivotal 68-week trial (Study 2 / STEP 1, adults with obesity or overweight plus a comorbidity), patients on Wegovy 2.4 mg lost an average of 14.9% of body weight vs 2.4% on placebo — a 12.4 percentage-point difference. 83.5% lost at least 5%, 66.1% at least 10%, and 47.9% at least 15% of their body weight.
What to know
Carries an FDA Boxed Warning for risk of thyroid C-cell tumors: in rodents semaglutide caused dose- and duration-dependent thyroid C-cell tumors, and it is contraindicated in anyone with a personal or family history of medullary thyroid carcinoma (MTC) or Multiple Endocrine Neoplasia syndrome type 2 (MEN 2). The label also warns of pancreatitis and gallbladder disease.
Zepbound (tirzepatide)
Also sold as Mounjaro (for type 2 diabetes)
- How it’s taken
- a once-weekly subcutaneous injection
- Approved for
- FDA-approved for chronic weight management in adults with obesity, or overweight with at least one weight-related condition (also approved for moderate-to-severe obstructive sleep apnea in adults with obesity).
- Average weight loss
- In the pivotal SURMOUNT-1 trial (Study 1, 72 weeks), mean body-weight reduction was 15.0% on 5 mg, 19.5% on 10 mg, and 20.9% on 15 mg, versus 3.1% for placebo.
What to know
Carries a boxed warning for risk of thyroid C-cell tumors (including medullary thyroid carcinoma); it is contraindicated in anyone with a personal or family history of MTC or with Multiple Endocrine Neoplasia syndrome type 2 (MEN 2), and the label also warns of pancreatitis and gallbladder disease.
Saxenda (liraglutide)
Same molecule (liraglutide) is also sold as Victoza, which is approved for type 2 diabetes.
- How it’s taken
- a once-daily injection under the skin (titrated to 3 mg daily over 4 weeks)
- Approved for
- FDA-approved for chronic weight management (reduce excess body weight and maintain weight reduction long term) in adults with obesity, or overweight plus a weight-related comorbidity, and in patients aged 12+ over 60 kg with obesity, alongside reduced-calorie diet and increased physical activity.
- Average weight loss
- In the pivotal 56-week trial (Study 1), patients on Saxenda lost a mean 7.4% of body weight vs 3.0% on placebo (a 4.5% placebo-adjusted difference); baseline mean weight was about 106 kg. 62% of Saxenda patients lost at least 5% and 34% lost more than 10% of body weight.
What to know
Boxed warning: liraglutide causes thyroid C-cell tumors in rodents; it is unknown whether it does in humans, and Saxenda is contraindicated in anyone with a personal or family history of medullary thyroid carcinoma (MTC) or Multiple Endocrine Neoplasia syndrome type 2 (MEN 2). Other GLP-1 class risks include pancreatitis and gallbladder disease.
Ozempic (semaglutide)
Also sold as Rybelsus (oral semaglutide tablets, for diabetes) and as Wegovy (semaglutide, for chronic weight management).
- How it’s taken
- a once-weekly subcutaneous injection
- Approved for
- FDA-approved for type 2 diabetes (glycemic control) and to reduce major adverse cardiovascular events in adults with type 2 diabetes and established cardiovascular disease. It is NOT approved for weight loss; weight use is off-label. The same molecule is FDA-approved for chronic weight management as Wegovy.
- Average weight loss
- Weight loss is a secondary endpoint in the diabetes trials, not an approved outcome. In the 30-week monotherapy trial (SUSTAIN 1), mean body weight fell about 3.8 kg (~8 lb) on the 0.5 mg dose and 4.7 kg (~10 lb) on the 1 mg dose, versus 1.2 kg (~3 lb) on placebo, from a baseline of roughly 90-97 kg.
What to know
Boxed warning for risk of thyroid C-cell tumors (medullary thyroid carcinoma); contraindicated in people with a personal or family history of MTC or Multiple Endocrine Neoplasia syndrome type 2 (MEN 2). The label also warns of pancreatitis and gallbladder disease.
Mounjaro (tirzepatide)
Also sold as Zepbound (tirzepatide), which IS the FDA-approved brand for chronic weight management and obstructive sleep apnea.
- How it’s taken
- a once-weekly subcutaneous injection
- Approved for
- FDA-approved for type 2 diabetes (as an adjunct to diet and exercise to improve glycemic control); not approved for weight. Weight use is off-label — the same molecule, tirzepatide, is FDA-approved for chronic weight management under the brand Zepbound.
- Average weight loss
- Mounjaro's own label is a diabetes label and does not carry a weight-management indication or pivotal weight trial. For tirzepatide's weight effect, the pivotal obesity trial (SURMOUNT-1 / Study 1, 72 weeks, adults with obesity or overweight without type 2 diabetes) — reported on the Zepbound label — showed a mean reduction in body weight of 15.0% at 5 mg, 19.5% at 10 mg, and 20.9% at 15 mg once weekly, versus 3.1% on placebo.
What to know
Carries a BOXED WARNING for the risk of thyroid C-cell tumors (contraindicated in anyone with a personal or family history of medullary thyroid carcinoma or MEN 2); label also warns of pancreatitis and gallbladder disease. Not a controlled substance.
Weight-loss pills
The oral options — generally a smaller average weight loss than the injections, but no needle, and some are far cheaper. Ranked by our recall-safety score.
Contrave (naltrexone and bupropion)
- How it’s taken
- a twice-daily oral tablet, taken morning and evening, dose-escalated over 4 weeks to the maintenance dose of two 8 mg/90 mg tablets twice daily (32 mg naltrexone / 360 mg bupropion per day)
- Approved for
- FDA-approved for chronic weight management — to reduce excess body weight and maintain weight reduction long term in adults with obesity, or overweight with at least one weight-related comorbidity, alongside a reduced-calorie diet and increased physical activity.
- Average weight loss
- In the pivotal 56-week COR-I trial, patients on CONTRAVE lost on average 5.4% of body weight versus 1.3% on placebo (ITT/LOCF); 42% of CONTRAVE patients lost at least 5% of body weight versus 17% on placebo.
What to know
Boxed warning for suicidal thoughts and behaviors — CONTRAVE contains bupropion, an antidepressant, which increased suicidal thinking and behavior in children, adolescents, and young adults; it is not approved for pediatric use. It also carries a seizure risk (contraindicated in patients with seizure disorders). If a patient has not lost at least 5% of body weight after 12 weeks at the maintenance dose, the label says to discontinue.
Qsymia (phentermine and topiramate)
- How it’s taken
- a once-daily oral extended-release capsule
- Approved for
- FDA-approved for chronic weight management — in adults with obesity, or overweight plus at least one weight-related condition, and in patients aged 12 and older with obesity — alongside a reduced-calorie diet and increased physical activity.
- Average weight loss
- At the recommended top dose (15 mg/92 mg), average (least-squares mean) weight loss from baseline at Week 56 (1 year) was about 10.9% of body weight in Study 1 (obesity) and 9.8% in Study 2 (overweight/obesity with comorbidities), versus roughly 1.2–1.6% on placebo — a placebo-adjusted difference of about 8.6–9.4%.
What to know
Contraindicated in pregnancy — topiramate raises the risk of major birth defects including cleft lip/cleft palate — so pregnancy must be ruled out before starting and effective contraception used during treatment; it also contains phentermine, a Schedule IV controlled substance, and is contraindicated in glaucoma or hyperthyroidism.
Xenical (orlistat)
Also sold over-the-counter as Alli (60 mg).
- How it’s taken
- an oral capsule, 120 mg taken three times a day with each main meal containing fat
- Approved for
- FDA-approved for obesity management (weight loss and weight maintenance) alongside a reduced-calorie diet, for a BMI of 30 or higher (or 27+ with risk factors like hypertension, diabetes, or dyslipidemia).
- Average weight loss
- Pooled data from five 1-year trials: mean weight loss at 1 year was 13.4 lbs on Xenical vs 5.8 lbs on placebo (intent-to-treat), a mean difference of about 3% of body weight. Of patients who completed the year, 57% on Xenical vs 31% on placebo lost at least 5% of baseline body weight.
What to know
Works by blocking absorption of dietary fat, which causes the hallmark GI effects (oily/fatty stools, fecal urgency, gas with discharge) and reduces absorption of fat-soluble vitamins — the label says to take a multivitamin with vitamins A, D, E, K and beta-carotene. Contraindicated in pregnancy, chronic malabsorption, and cholestasis; rare cases of severe liver injury and of oxalate kidney injury have been reported. Not a controlled substance.
phentermine (phentermine)
Also sold as Adipex-P and Lomaira; combined with topiramate as Qsymia.
- How it’s taken
- a daily pill (usual adult dose one 37.5 mg tablet before or 1-2 hours after breakfast; late-evening dosing avoided due to insomnia)
- Approved for
- FDA-approved as a short-term (a few weeks) adjunct to diet, exercise, and behavioral modification for exogenous obesity (BMI >=30, or >=27 with risk factors).
- Average weight loss
- The label reports no percent-of-body-weight figure. Its Clinical Studies section states only that drug-treated patients lost more weight than placebo, with the magnitude of the extra weight loss being "only a fraction of a pound a week," greatest in the first weeks, over trials of a few weeks' duration — an effect the label calls "clinically limited."
What to know
Short-term use only (a few weeks); a Schedule IV controlled substance with abuse potential. Contraindicated in cardiovascular disease (coronary artery disease, stroke, arrhythmias, heart failure, uncontrolled hypertension), hyperthyroidism, glaucoma, agitated states, history of drug abuse, MAO-inhibitor use within 14 days, and pregnancy/nursing.
How to read the weight-loss numbers
Each average comes from that drug’s own pivotal trial, alongside diet and exercise — not a head-to-head study, so the percentages are notdirectly comparable, and your result can be more or less. Weight also tends to return after stopping. A bigger trial average is not a reason to choose a drug on your own: the safety warnings, your other conditions and medicines, cost and access all matter, and that weighing is a prescriber’s job. Also see the deeper GLP-1 comparison and GLP-1 side effects.
Frequently asked questions
- Is Ozempic a weight-loss drug?
- Ozempic is FDA-approved for type 2 diabetes, not weight loss — using it for weight is off-label. Its exact same molecule, semaglutide, IS FDA-approved for chronic weight management, but under a different brand and dose: Wegovy. The same is true of Mounjaro (diabetes) and Zepbound (weight loss), which are both tirzepatide.
- What is the most effective weight-loss medication?
- In the pivotal trials, the injectable GLP-1 and GIP/GLP-1 drugs produced the largest average weight loss — Wegovy (In the pivotal 68-week trial), Zepbound (In the pivotal SURMOUNT-1 trial) — more than the older oral options. But the trials are not head-to-head, "most effective on average" is not "best for you," and the right choice depends on your health, side-effect tolerance, cost and access — a prescriber's decision.
- Are weight-loss injections safe?
- The GLP-1 injections carry an FDA boxed warning about a risk of thyroid C-cell tumours seen in rodents, and can cause pancreatitis and gallbladder problems; the oral options have their own serious warnings (Contrave's suicidality boxed warning, Qsymia's pregnancy contraindication). None is a casual choice. Read each drug's warning above and take the decision to a prescriber.
Sources: each drug’s FDA label (openFDA / DailyMed), linked on its card. Weight-loss figures are the averages the pivotal trials reported and are reproduced, not computed by us. This is general reference information, not medical advice, and not a recommendation to take any drug.