There is no single “best” weight loss pill for everyone, but the most effective medications available right now are the newer injectable and oral prescriptions that mimic gut hormones. In clinical trials, tirzepatide (Zepbound) produced average weight loss of about 21% of body weight at the highest dose, making it the strongest performer on the market. Semaglutide (Wegovy) is close behind at roughly 15%. Both require a prescription, and the right choice depends on your health profile, budget, and what your body tolerates.
How the Strongest Options Compare
Six prescription medications currently have FDA approval for long-term weight management. They fall into three categories based on how they work, and their results vary dramatically.
The GLP-1 and dual-hormone drugs are in a class of their own. Tirzepatide (Zepbound) mimics two gut hormones that regulate appetite and blood sugar. In its landmark trial, patients lost an average of 15%, 19.5%, or 20.9% of their body weight depending on the dose, over 72 weeks. Semaglutide (Wegovy) works through one of those same hormones, and patients in its main trial lost an average of 14.9% of body weight over 68 weeks. For context, losing 15 to 20% of your body weight means a 250-pound person dropping 37 to 50 pounds.
The older options produce more modest results. Phentermine-topiramate (Qsymia) combines a stimulant with a seizure medication that suppresses appetite. Naltrexone-bupropion (Contrave) pairs an addiction treatment drug with an antidepressant. Both typically produce single-digit percentage weight loss. Orlistat (Xenical, or the lower-dose over-the-counter version Alli) blocks about 30% of the fat you eat from being absorbed, but its results are the smallest of the group.
How These Drugs Actually Work
The newer medications (semaglutide and tirzepatide) act on two fronts. In the brain, they influence the regions that control hunger and fullness, essentially turning down the volume on appetite signals. In the gut, they slow how quickly your stomach empties food, so you feel satisfied longer after eating. They also improve how your body handles blood sugar by boosting insulin release and dialing back the hormone that raises it.
This is fundamentally different from older approaches. Phentermine is a stimulant that suppresses appetite through adrenaline-like effects on the nervous system. It’s only approved for short-term use, typically a few weeks, because of cardiovascular risks including elevated blood pressure, rapid heart rate, and rare but serious concerns like pulmonary hypertension and heart valve problems. It cannot be used by anyone with a history of heart disease, stroke, or uncontrolled high blood pressure.
Orlistat takes yet another approach, physically preventing your intestines from absorbing dietary fat. The unabsorbed fat has to go somewhere, which leads to the drug’s well-known side effects: oily stools, gas with discharge, fecal urgency, and sometimes loss of bowel control. In clinical trials, over a quarter of patients experienced oily spotting, and about 8% reported fecal incontinence.
What an Oral Pill Can Do
One of the biggest complaints about the most effective weight loss drugs is that they’re injections. A new oral GLP-1 pill called orforglipron is working through clinical trials and showing promising results. At its highest tested dose (36 mg), patients lost an average of 11.2% of their body weight over 72 weeks, with about 55% of patients on that dose losing 10% or more. That’s less than the injectable options but substantially more than older oral medications, and it comes without needles. Its side effect profile looks similar to other GLP-1 drugs, primarily nausea and digestive issues.
Cost and Access
Price is often the deciding factor. With commercial insurance that covers Wegovy, copays can be as low as $25 per month. Without coverage, you’re looking at $149 to $349 per month depending on the dose and available savings programs. Zepbound has a similar price structure. Many insurance plans still don’t cover weight loss medications, or they require you to meet specific criteria like a BMI of 30 or higher (or 27 with related health conditions like diabetes or high blood pressure).
Orlistat is the only option with an over-the-counter version (Alli, at a lower 60 mg dose), making it the most accessible without a prescription. But given its modest effectiveness and uncomfortable side effects, it’s rarely a first choice for people with significant weight to lose.
Weight Regain After Stopping
One critical detail that often gets overlooked: these medications work for as long as you take them. Research tracking patients after they stopped weight loss drugs found an average regain of about 0.4 kg (just under a pound) per month. At that rate, people were projected to return to their pre-treatment weight within roughly 1.7 years. This means most people need to think of these medications as long-term, potentially lifelong treatments, similar to blood pressure or cholesterol drugs. Stopping and expecting the weight to stay off is, for most people, unrealistic.
Why Over-the-Counter Supplements Fall Short
If you’re hoping to skip the prescription and find something effective at the drugstore, the evidence is discouraging. Green tea extract is one of the most studied weight loss supplements, and the results are consistently underwhelming. A Cochrane Review of 14 randomized controlled trials found green tea reduced body weight by less than 1 kg (about 2 pounds) more than placebo. When researchers looked only at the most methodologically rigorous studies, the difference disappeared entirely. A separate 12-month trial of high-dose green tea catechins in postmenopausal women found no effect on weight, BMI, or waist circumference.
Beyond being ineffective, some supplements carry real risks. Green tea extracts have been linked to at least 50 reported cases of liver damage since 2006, with the risk increasing when taken on an empty stomach. The broader supplement market is largely unregulated, and no over-the-counter weight loss product has demonstrated anything close to the results seen with prescription medications.
Who Should Not Take These Medications
GLP-1 drugs like semaglutide and tirzepatide are not appropriate for everyone. They should not be used by people with a personal or family history of a type of thyroid cancer called medullary thyroid carcinoma, or those with a condition called multiple endocrine neoplasia syndrome type 2. People with severe gastroparesis, where the stomach already empties too slowly, are also poor candidates since these drugs further slow gastric emptying. And despite sometimes being discussed for weight loss in people with type 1 diabetes, these medications are not designed for that condition and should not be used for it.
The most common side effects across all GLP-1 drugs are gastrointestinal: nausea, vomiting, diarrhea, and constipation. These tend to be worst during the dose-escalation phase (the first few months when the dose gradually increases) and often improve with time. Starting at a low dose and increasing slowly is the standard approach to minimize these effects.