Several prescription and over-the-counter pills can help you lose weight, ranging from older oral medications to newer drugs that produce dramatic results. The most effective options require a prescription and work best alongside changes to diet and exercise. Which one fits your situation depends on your health profile, your BMI, and what you’re willing to tolerate in terms of side effects and cost.
Who Qualifies for Prescription Weight Loss Pills
Prescription weight loss medications are approved for adults with a BMI of 30 or greater. If your BMI is 27 or higher and you have a weight-related condition like high blood pressure or type 2 diabetes, you also qualify. Your doctor will evaluate whether medication makes sense given your overall health, other medications you take, and how much weight you need to lose.
Oral Prescription Pills
If you specifically want a pill you swallow (rather than an injection), a few prescription options exist.
Phentermine-topiramate (Qsymia) is one of the more effective oral options. It combines a stimulant that suppresses appetite with a drug originally used for seizures and migraines that also reduces hunger. In a large clinical trial, people taking the higher dose lost about 9.8% of their body weight over 56 weeks, compared to 1.2% for placebo. Around 70% of people on the higher dose lost at least 5% of their starting weight, and nearly half lost 10% or more. Common side effects include tingling in the hands and feet, dry mouth, constipation, and trouble sleeping.
Naltrexone-bupropion (Contrave) pairs two medications that affect reward and craving pathways in the brain. One component is used to treat addiction, the other is an antidepressant. Together they reduce appetite and food cravings. Weight loss is more modest than with Qsymia or the injectable drugs, typically in the range of 5 to 6% of body weight. Side effects can include nausea, headache, and constipation.
Phentermine on its own is approved only for short-term use, generally 12 weeks. It’s a stimulant that curbs appetite but can raise heart rate and blood pressure. Doctors sometimes prescribe it as a starting point before transitioning to a longer-term medication.
Injectable Medications
The most powerful weight loss drugs available right now are not pills. They’re weekly injections, but they’re worth knowing about because they dominate the conversation and produce far greater results than any oral option.
Semaglutide (Wegovy) mimics a gut hormone called GLP-1 that signals fullness to your brain and slows how quickly food leaves your stomach. In clinical trials, the standard 2.4 mg dose produced average weight loss of 17.5%. A newer, higher dose currently under review pushed that to 20.7%. More than 92% of participants on either dose lost at least 5% of their body weight.
Tirzepatide (Zepbound) targets two gut hormones instead of one. At the highest dose in its pivotal trial, participants lost an average of 20.9% of their body weight over 72 weeks. That’s roughly 50 pounds for someone starting at 240.
Both drugs work by activating satiety neurons in the brain, making you feel full sooner and reducing the mental “noise” around food. They’re injected once a week using a pen device similar to what people with diabetes use.
The One Over-the-Counter Option
Only one FDA-approved weight loss pill is available without a prescription: orlistat 60 mg, sold as Alli. It works completely differently from every other drug on this list. Instead of affecting your brain or appetite, it blocks your body from absorbing about 25% of the fat you eat. That unabsorbed fat passes through your digestive system, which is both the mechanism and the main drawback.
You take one pill within an hour of each fat-containing meal, up to three times a day. In studies, people who combined Alli with a calorie-restricted diet and exercise lost an average of 5.7 extra pounds over a year compared to diet and exercise alone. More than 40% of users lost at least 5% of their body weight. That’s meaningful but modest. The prescription-strength version (Xenical, 120 mg) roughly doubles the fat-blocking effect. Side effects for both include oily stools, gas, and urgent bowel movements, especially if you eat high-fat meals.
Common Side Effects Across Drug Types
The oral pills each come with their own side effect profiles (stimulant effects for phentermine, tingling for topiramate, nausea for naltrexone-bupropion). But the GLP-1 based drugs share a consistent pattern: nausea, vomiting, diarrhea, and constipation are by far the most common complaints. These gastrointestinal effects are usually worst during the dose-escalation period and improve over weeks as your body adjusts.
Less common but more serious risks with GLP-1 drugs include pancreatitis (inflammation of the pancreas causing severe abdominal pain), gastroparesis (where food movement out of the stomach slows dramatically or stops), bowel obstruction, and gallstone attacks. These are rare, but they’re the reason these medications require medical supervision and aren’t sold over the counter.
How Much Weight You Can Realistically Expect to Lose
The range is wide depending on which medication you use. Here’s a rough hierarchy of average body weight lost in clinical trials:
- Alli (OTC orlistat): about 2 to 3% beyond diet and exercise alone
- Contrave: about 5 to 6%
- Qsymia (higher dose): about 10%
- Wegovy (semaglutide 2.4 mg): about 17.5%
- Zepbound (tirzepatide, highest dose): about 21%
These are averages. Some people respond much better, others less so. Response tends to be apparent within the first few months. If you haven’t lost at least 5% of your body weight after three to six months on a medication, your doctor will likely reassess whether it’s worth continuing.
What Happens When You Stop
This is the part most people don’t hear about until it’s too late. A 2025 systematic review in The BMJ analyzed 37 studies on weight change after stopping weight loss medications. The findings are sobering: people regained weight at an average rate of about 0.4 kg (just under a pound) per month after stopping. For the newer, more powerful drugs like semaglutide and tirzepatide, regain was faster, averaging about 9.9 kg (roughly 22 pounds) within the first year off treatment.
The projected timeline to return to your original starting weight was about 1.5 years after stopping the newer drugs and 1.7 years after stopping weight loss medications in general. This doesn’t mean the medications “don’t work.” It means obesity is a chronic condition, and these drugs treat it the same way blood pressure pills treat hypertension. They work while you take them. For many people, staying on medication long-term is part of the plan.
Choosing the Right Option
If you want an oral pill specifically, Qsymia offers the best balance of effectiveness and convenience among currently available tablets. If you’re open to weekly injections and qualify, semaglutide and tirzepatide produce results that oral medications simply can’t match yet. If you want something you can try without a prescription, Alli is your only regulated option, though expectations should be modest.
Cost is a major factor. The injectable GLP-1 drugs carry list prices above $1,000 per month, and insurance coverage varies widely. Older oral options like phentermine are cheap but limited to short-term use. Qsymia and Contrave fall somewhere in between. Whatever path you explore, the medications work best when combined with dietary changes and physical activity, not as a replacement for them.