Appetite Suppressants: Every FDA-Approved Drug and What Its Label Shows

The strongest appetite suppressants are prescription drugs, and for ordinary obesity the strongest of those are the GLP‑1 class: on its FDA label, Zepbound took off 17.8 percentage points more body weight than placebo over 72 weeks, and Wegovy 12.4.^[11][10] The older stimulant pills, phentermine among them, are approved only for “a few weeks,” and their own labels put the extra loss over placebo at “a fraction of a pound a week.”^[1] No appetite suppressant is FDA-approved for sale without a prescription. The one over-the-counter weight-loss drug, orlistat (Alli), blocks fat absorption rather than hunger,^[14] and products sold as appetite-suppressant supplements have little trial support and keep turning up with hidden prescription drugs inside.^[18]

Every prescription appetite suppressant, by the label's own numbers

Each drug below is FDA-approved for weight loss and works at least partly by reducing appetite or food intake, according to its label. The column that matters is the difference from placebo: how much more weight people lost on the drug than people taking a dummy pill or shot under the same diet and exercise advice.

Sources for each row: Zepbound,^[11] Wegovy injection and tablet,^[10] Qsymia,^[7] Foundayo,^[12] Saxenda,^[9] Contrave,^[8] the four stimulants^{[1][2][3][5][6]} and Imcivree.^[13] The Wegovy 2.4 mg row is the trial in adults without diabetes; the Qsymia row is its trial limited to people whose BMI was 35 and above; the Foundayo row is its trial in adults without diabetes. On every drug that reported a separate trial in type 2 diabetes, the gain over placebo was smaller in that trial.

How each one reduces appetite

The drugs reach the same result by different routes, which each label describes in its mechanism section.

• GLP‑1 drugs (Wegovy, Saxenda, Foundayo) copy a gut hormone the labels call “a physiological regulator of appetite and caloric intake,” acting on brain areas that control eating.^[10][9] Foundayo’s label is the most direct: it “decreases food intake,” an effect “likely mediated by decreased appetite.”^[12] Patients often describe the change as quieter food noise.
• Tirzepatide (Zepbound) adds a second hormone, GIP, which its label says may further contribute to regulating food intake.^[11]
• Stimulants (phentermine, diethylpropion, phendimetrazine, benzphetamine) are chemically related to amphetamine. Qsymia’s label describes phentermine’s action as catecholamine release in the hypothalamus “resulting in reduced appetite and decreased food consumption.”^[7]
• Contrave works on two brain systems: the hypothalamus, which its label calls the “appetite regulatory center,” and the dopamine reward circuit.^[8]
• Setmelanotide (Imcivree) switches on the MC4 receptor, a hunger and satiety pathway that is broken in a handful of rare genetic disorders and in hypothalamic damage.^[13]

The old stimulant pills: approved for weeks, not months

Phentermine, diethylpropion, phendimetrazine and benzphetamine are the drugs most people mean by “appetite suppressant pills.” Phentermine was first approved in 1959.^[1] All four labels limit use to “a few weeks” alongside diet, and all four carry the same paragraph about the evidence behind them:

The magnitude of increased weight loss of drug-treated patients over placebo-treated patients is only a fraction of a pound a week. The rate of weight loss is greatest in the first weeks of therapy for both drug and placebo subjects and tends to decrease in succeeding weeks.

— Phentermine hydrochloride prescribing information, section 14

Lomaira’s label adds that the trials lasted only weeks while obesity runs for years, so the extra weight loss over diet alone “must be considered clinically limited.”^[2] Phentermine’s label also expects the effect to fade: tolerance to the appetite effect “usually develops within a few weeks,” and if it does, the drug should be stopped rather than the dose raised.^[1]

Sources: phentermine and Lomaira,^[1][2] diethylpropion,^[3][4] phendimetrazine^[5] and benzphetamine.^[6] Modern trials give a better sense of size than the labels. In a 28-week trial run for Qsymia’s approval, 46.2% of people given phentermine 15 mg alone reached 5% weight loss or more, compared with 15.5% given placebo.^[15] In a six-month Brazilian trial of 69 adults, diethylpropion produced 9.8% weight loss against 3.2% on placebo, with no difference in blood pressure, pulse or psychiatric scores.^[16] Both are small or short, and neither changes what the labels approve.

The stimulant labels share their warnings too. Phentermine is contraindicated with a history of heart disease, stroke or uncontrolled blood pressure, and its label recalls the lung and heart-valve disease reported with fen-phen, the phentermine and fenfluramine pairing of the 1990s.^[1] Diethylpropion’s label makes combining it with any other appetite suppressant a contraindication.^[3] Benzphetamine is contraindicated in anyone who is or may become pregnant.^[6] Whether phentermine can be added to a GLP‑1 is covered in phentermine and a GLP-1 together, and how both raise pulse in GLP-1 drugs, heart rate and palpitations.

Qsymia and Contrave: the two long-term pills

Qsymia pairs a low dose of phentermine with topiramate in one daily capsule and, unlike phentermine alone, is approved for long-term use. At its top dose, adults lost 10.9% of their weight against 1.6% on placebo over a year, though 40% of people in that trial left before the end.^[7] Because topiramate can cause birth defects, Qsymia is dispensed only through certified pharmacies under a safety program, and the label recommends a negative pregnancy test before starting and every month after.^[7]

Contrave combines naltrexone with extended-release bupropion. In its main trial adults lost 5.4% against 1.3% on placebo, and nearly half of both groups left the trials before week 56.^[8] Because one of its two ingredients is the antidepressant bupropion, it carries the antidepressant boxed warning on suicidal thinking, and it cannot be taken with Wellbutrin or other bupropion products; more on that in antidepressants and a GLP-1. The two pills are compared directly in Contrave vs Qsymia, and each against the injections in Wegovy vs Contrave and Zepbound vs Qsymia.

Three of the long-term drugs build in a checkpoint. Contrave and Qsymia tell prescribers to stop the drug when weight is down by less than 5% after 12 weeks at the full dose;^[8][7] Saxenda says to stop at 16 weeks if the loss is under 4%.^[9] A drug that has not worked by then is unlikely to start.

Some telehealth sellers offer the ingredients rather than the branded combinations. Hone Health lists naltrexone, bupropion, phentermine and topiramate on its weight formulary, beside compounded liraglutide, and Tyde Wellness lists low-dose naltrexone next to compounded semaglutide and tirzepatide. The label numbers above belong to the approved combination products, so ask the prescriber how a separately dosed version compares.

The GLP-1 drugs: shots and now pills

The GLP‑1 class is where the large numbers are. Zepbound’s highest dose produced 20.9% weight loss over 72 weeks, Wegovy’s new 7.2 mg dose 18.8%, and the original 2.4 mg dose 14.9%.^[11][10] There are now two daily pills in the class. The Wegovy pill, 25 mg of semaglutide, produced 13.6% against 2.4% on placebo,^[10] and Foundayo (orforglipron) 11.1% against 2.1%.^[12] How the pills compare with the shots is covered in is the pill as good as the shot? and Foundayo on its own in Foundayo (orforglipron).

Professional guidance ranks them the same way. The American College of Physicians’ 2026 guideline names semaglutide and tirzepatide as first-line weight-loss drugs, phentermine–topiramate second, liraglutide third and naltrexone–bupropion fourth. Phentermine on its own is not on the list.^[17] What the GLP‑1 drugs cost and how to get them covered is in the cheapest GLP-1 without insurance.

Setmelanotide has a large effect in a narrow group. In 142 people with obesity from hypothalamic damage, it lowered BMI by 18.4% more than placebo and reduced reported hunger.^[13] Its label is limited to that condition and a few rare genetic ones, and says it would not be expected to work in general obesity. Why GLP‑1 drugs struggle in the same patients is covered in when the appetite center is damaged.

Over-the-counter appetite suppressants: none are approved

No drug sold without a prescription in the US is approved to suppress appetite. In a 1991 final rule, FDA classed 111 ingredients then used in over-the-counter weight-control products as nonmonograph, meaning they could not be sold for that purpose without approval. Phenylpropanolamine, the ingredient in older drugstore diet pills, came off the market after November 2000, when FDA asked companies to stop selling it.^[25] A Yale case-control study had linked phenylpropanolamine appetite suppressants to hemorrhagic stroke in women, with an odds ratio of 16.6 and a very wide confidence interval.^[24]

The one FDA-approved weight-loss drug on pharmacy shelves is orlistat 60 mg, sold as Alli. It is not an appetite suppressant. Its label says it works “by preventing the absorption of some of the fat you eat,” which is why it causes oily stools when meals are fatty.^[14]

What FDA keeps finding in weight-loss supplements

The commonest hidden ingredient is sibutramine, an appetite suppressant that was once a prescription drug. In a trial of 9,804 people with heart disease or diabetes, sibutramine raised the rate of heart attack, stroke, cardiac arrest or cardiovascular death to 11.4% from 10.0% on placebo,^[23] and it was withdrawn from the US market in October 2010.^[19] Of 317 weight-loss supplements FDA flagged for hidden drugs between 2007 and 2016, 269 (84.9%) contained sibutramine.^[22]

The finds have continued. FDA notices from 2026 alone include:

• Detoxi Slim (July 2026): sibutramine.^[19]
• Esbelta Intense Loss (August 2026): sibutramine, two chemical cousins of it, and sildenafil, the drug in Viagra.^[20]
• Lipofit Extreme 2.0 Fat Burner (June 2026): the antidepressant fluoxetine in the morning tablets and 2,4‑dinitrophenol, a toxic industrial chemical, in the night tablets.^[21]

A product that works suspiciously well may be working because of a drug that is not on the label. The site’s FDA warning-letter register tracks enforcement against sellers of GLP‑1 drugs specifically.

Supplements with honest labels: small or no effect

Supplements that contain what they say mostly do little. A systematic review for The Obesity Society screened 315 randomized trials of 14 supplements and alternative therapies. Only 52 were judged low risk of bias with enough data, and 16 of those found a weight difference, ranging from 0.3 to 4.93 kg.^[26] A meta-analysis of 54 placebo-controlled trials of herbal products found no effect for green tea or Garcinia cambogia, and concluded there was not enough evidence to recommend any herbal medicine for weight loss.^[27] Products now marketed as “GLP‑1” supplements, such as berberine, are reviewed in GLP-1 supplements: do they work?

Who should be careful with any appetite suppressant

A drug that takes away hunger is not neutral for someone with a history of anorexia or bulimia. Contrave is contraindicated in anyone with a current or past diagnosis of either, because of seizure risk.^[8] That history belongs in the first conversation with a prescriber; see GLP-1 drugs and eating disorders. Phentermine and Qsymia are contraindicated in pregnancy, and Contrave’s label says to stop it once pregnancy is recognized.^[1][7][8] The stimulants are also a poor fit for anyone with heart disease, uncontrolled blood pressure, glaucoma, an overactive thyroid or a history of drug misuse, all of which appear among their contraindications.^[1][3][6]

What to ask a prescriber

1. Is this for a few weeks or for the long term? The four stimulants are labeled for short-term use only. Qsymia, Contrave and the GLP‑1 drugs are labeled for long-term weight management.
2. What result should I expect, and when will we check? Several labels set a stop point at 12 or 16 weeks if weight has not fallen enough.
3. Does my heart or blood pressure history rule out a stimulant?
4. Could I become pregnant while taking it? Qsymia’s label recommends a pregnancy test before starting and every month, and phentermine and Qsymia are contraindicated in pregnancy.
5. What else am I taking that interacts? Bring antidepressants, opioids, seizure medicines and any supplements to the appointment.