Several FDA-approved medications can help you lose a meaningful amount of weight, ranging from newer injectable and oral drugs that mimic gut hormones to older pills that suppress appetite or block fat absorption. The most effective options require a prescription and are designed for adults with a BMI of 30 or higher, or 27 and above with a weight-related health condition like high blood pressure or type 2 diabetes. One option, a lower-strength fat blocker called Alli, is available over the counter. Here’s what each type does, how much weight you can realistically expect to lose, and what they cost.
GLP-1 and Dual-Action Medications
The most talked-about weight loss drugs right now work by mimicking hormones your gut naturally produces after eating. These hormones, called GLP-1 and GIP, slow down how fast your stomach empties and act on areas of your brain that control hunger and fullness. The medications bind to the same receptors as the natural hormones but produce a much stronger, longer-lasting effect. The result is that you feel full sooner, stay satisfied longer, and think about food less throughout the day.
Tirzepatide (sold as Zepbound for weight loss) targets both GLP-1 and GIP receptors, and it currently produces the largest weight loss of any approved medication. In a head-to-head clinical trial, participants on tirzepatide lost about 50 pounds on average, or 20.2% of their starting body weight. Semaglutide (sold as Wegovy) targets GLP-1 alone and produced an average loss of 33 pounds, or 13.7% of body weight, in the same trial. Both are weekly injections, though an oral version of semaglutide (Wegovy Pill) received FDA approval in late 2025.
A newer option called orforglipron (Foundayo) is a pill rather than an injection. It’s a small-molecule GLP-1 drug, meaning it can be manufactured differently from the injectable versions. Liraglutide (Saxenda) is an older daily injection in this class that’s still prescribed but produces more modest results than the newer weekly options.
How Quickly You’ll See Results
If you start a GLP-1 medication, don’t expect dramatic changes in the first month. Most noticeable weight loss begins around week 8, and the first four to eight weeks on a low starter dose aren’t representative of what the drug can do. The fastest rate of loss typically happens between weeks 12 and 28, then gradually slows as your body settles at a lower weight. By about week 36, most people’s rate of loss has slowed significantly. Clinical trials tracked continued progress through 72 weeks, with total losses reaching 17% to 22.5% of body weight for the strongest medications before leveling off into a maintenance phase.
Older Prescription Pills
Before GLP-1 drugs arrived, several oral medications were the standard options for weight loss. They produce smaller results but cost less and may be appropriate depending on your health profile.
Phentermine (Adipex, Lomaira) is one of the most widely prescribed weight loss pills in the U.S. It works as an appetite suppressant and is typically used short-term. It comes as a tablet or capsule taken once or up to three times daily, depending on the formulation.
Qsymia combines phentermine with topiramate, a drug originally used for seizures and migraines. The combination works better than phentermine alone. In large clinical trials lasting up to a year, patients on the recommended dose lost an average of 8.9% more body weight than those on a placebo.
Contrave pairs an opioid-blocking drug with an antidepressant. It targets the reward and hunger pathways in your brain. It’s less potent than the options above: clinical trials showed an average weight loss of about 4% over placebo at one year, with 42% of patients losing at least 5% of their body weight compared with 17% on placebo. Patients typically lose between 5% and 10% of their starting weight. It’s taken as a daily pill.
The Only Over-the-Counter Option
Alli is the only FDA-approved, non-prescription weight loss pill. It contains orlistat at 60 mg per capsule, which is half the strength of the prescription version (Xenical, at 120 mg). Orlistat works completely differently from the drugs above. Instead of acting on your brain or hormones, it blocks enzymes in your gut that break down fat. When you take it with a meal, roughly 25% of the fat you eat passes through your body undigested.
The tradeoff is noticeable. Eating high-fat meals while on orlistat commonly causes oily stools, gas, and urgent bowel movements. These side effects are manageable if you keep your fat intake low, but they’re the main reason many people stop taking it. Weight loss with orlistat is modest compared to prescription alternatives.
What About Weight Loss Supplements?
Walk into any pharmacy or browse online and you’ll find shelves of supplements marketed for weight loss: green tea extract, garcinia cambogia, conjugated linoleic acid, and dozens more. These are not held to the same standard as the drugs listed above. The FDA does not test or approve dietary supplements before they’re sold. Manufacturers don’t have to prove their products work, and they don’t have to submit safety evidence to the FDA before putting them on shelves (with narrow exceptions for brand-new ingredients). The agency can only step in after a product is already on the market and causing problems.
Any supplement that explicitly claims to treat or cure obesity is, by legal definition, an unapproved drug. The carefully worded claims you see on packaging (“supports metabolism,” “promotes a healthy weight”) are deliberately vague to stay within supplement regulations. No over-the-counter supplement has clinical evidence comparable to what’s required for FDA-approved medications.
Who Shouldn’t Take These Medications
Each weight loss medication has specific conditions that rule it out. GLP-1 drugs, including semaglutide, tirzepatide, and liraglutide, should not be used by anyone with a personal or family history of medullary thyroid cancer or a rare condition called MEN 2. Qsymia is off-limits if you have glaucoma or an overactive thyroid. Contrave cannot be used by people with uncontrolled high blood pressure, a seizure history, or an eating disorder like anorexia or bulimia. It’s also incompatible with opioid use or recent alcohol withdrawal. Orlistat shouldn’t be taken if you have trouble absorbing nutrients or certain bile duct problems.
None of these medications should be taken during pregnancy or while breastfeeding.
Cost and Access
Price has been the biggest barrier to GLP-1 medications. Wegovy has listed at around $1,350 per month, and Zepbound at roughly $1,086 per month, though actual out-of-pocket costs vary widely depending on insurance. Recent federal pricing agreements have started to bring those numbers down. Under a government discount program, injectable semaglutide and tirzepatide are set to drop to about $350 per month, with the oral Wegovy pill priced at $150 per month. Medicare beneficiaries would pay a copay of $50 per month under the same arrangement.
Older oral medications like phentermine, Qsymia, and Contrave are significantly cheaper, often available as generics for a fraction of the cost. Alli, the over-the-counter option, typically runs $30 to $60 per month depending on where you buy it. For many people, the choice of medication comes down not just to effectiveness but to what their insurance covers and what they can afford long-term, since weight tends to return when these drugs are stopped.