Top Weight Loss Medications

The pharmacological treatment of obesity is a fast-changing landscape, and care providers must strive continuously to stay current. Before 2012, there were few weight loss medications approved by the FDA. The top anti-obesity medications (AOMs) at that time were phentermine, marketed as Lomaira and Adipex-P, and orlistat, marketed as Xenical and Alli.

In the 2020s, glucagon-like peptide-1 receptor agonists (GLP-1 receptor agonists) exploded in popularity and media attention. Next came a dual receptor agonist, Mounjaro, which is indicated for type 2 diabetes, and Zepbound, which is indicated for obesity. Currently, these medications are administered by injection, but oral weight loss drugs in the same category may soon follow.

A study from FAIR Health published in May 2025 reports that more than 2% of U.S. adults took a GLP-1 for weight loss in 2024. (Many more take them for other indications.) According to the Kaiser Family Foundation, public awareness has ramped up, with 32% of adults now saying they have heard “a lot” about these drugs.

With a growing selection of weight loss medications available, patients may ask what the strongest or most effective weight loss prescription medication is, and which one is best for them. The answer is complicated, and newer is not always better.

Criteria for Weight Loss Medication Prescriptions

Determining whether someone is a candidate for weight loss medications begins with BMI. Most medications are prescribed for someone with a BMI of 30 or greater, or a BMI of 27 or greater if the person has weight-related health conditions.

For each individual case, the doctor and patient should discuss the patient’s current health issues, other medications, and family medical history. The medication’s cost and side effects will also affect the decision.

Other considerations when prescribing anti-obesity medications (AOMs) include:

• The amount of weight reduction and duration will vary by patient.
• The average weight loss varies from 5% to 21%, with some people losing more and some people losing less. Some people do not lose weight with AOMs.
• If weight loss of at least 5% is not achieved within 12-16 weeks at the maximum tolerated dose, then an alternative AOM should be considered.
• Most people regain weight if AOMs are discontinued. Consequently, long-term therapy is recommended.

While some weight loss medications are FDA-approved only for adults, some—including semaglutide and liraglutide—are approved for children 12 and older with a BMI >/= 95^th percentile. All of the medications discussed here are contraindicated for pregnancy.

Currently Available Weight Loss Medications

Some weight loss medications have been on the market for many years, and new ones emerge frequently. It can be easy to overlook first-generation AOMs, but these may be appropriate for some patients, especially when cost is a factor. Commonly prescribed weight loss medications include:

Semaglutide (Wegovy, Ozempic)

Wegovy is a brand name for semaglutide, a GLP-1 receptor agonist. It was FDA-approved in 2021. It is administered as an injection and approved for use in adults and children aged 12 years or more with obesity (BMI ≥30 for adults, BMI ≥ 95th percentile for age and sex for children) or some adults with excess weight (BMI ≥27) who also have weight-related medical problems. The dose must be increased gradually over 16 to 20 weeks to arrive at the 2.4 mg dosage. This progression can help to alleviate side effects, which include gastrointestinal symptoms, headache, dizziness, and fatigue. It is intended to be used indefinitely, in combination with a healthy diet and exercise.

Ozempic may be a more familiar name to some patients. It is also semaglutide, but approved to treat type 2 diabetes.

Tirzepatide (Zepbound, Mounjaro)

Zepbound is approved to treat obesity in adults with a BMI of 30 or greater. It is both a GLP-1 and a GIP receptor agonist. Like semaglutide, it works by reducing appetite and is meant to be used in combination with diet and exercise to lose weight. It is also administered as an injection.

Tirzepatide was previously approved to treat type 2 diabetes as Mounjaro, and it goes by that name only in some countries.

Liraglutide (Saxenda)

Liraglutide is a daily injectable medication that acts on hormones that send signals from the gut to the brain to make the patient feel full quicker and decrease hunger signals. Doses start at 0.6 mg to 3 mg a day. Some patients may lose 5–10% of body weight, especially with the higher dose of liraglutide. Unlike Wegovy and Zepbound, it is injected once daily instead of weekly.

Liraglutide is also approved for Type 2 Diabetes, under the brand name Victoza.

Side effects include nausea, diarrhea, constipation, vomiting, headache, decreased appetite, dyspepsia, fatigue, dizziness, abdominal pain, increased lipase, and renal insufficiency. It is contraindicated in patients with a personal or family history of medullary thyroid carcinoma or Multiple Endocrine Neoplasia syndrome type 2.

Phentermine (Adipex, Suprenza, Lomaira)

Phentermine is the oldest and most widely used weight loss medication. It was originally used as a short-term medication to jump-start weight loss, but now newer medical guidelines have added it to long-term therapy. Some patients may lose about 5% of their body weight by taking phentermine.

In the U.S., phentermine is available as a 15 mg or 30 mg capsule, or an 18.75 mg or 37.5 mg tablet. Side effects include headache, overstimulation, high blood pressure, insomnia, rapid or irregular heart rate, and tremor. Note that Suprenza contains tartrazine, an ingredient to which some people may have an allergic reaction.

Interactions may occur during or within 14 days following the use of monoamine oxidase (MAO) inhibitors, sympathomimetics, alcohol, adrenergic neuron-blocking drugs, and possibly some anesthetic agents.

Phentermine-topiramate (Qsymia)

Topiramate can be combined with phentermine to decrease appetite and cravings. Combining the two drugs increases efficacy.

Adults with migraines and obesity are good candidates for this weight-loss medication. Some patients may lose an average of 5–10% of body weight. If more than 5% weight loss is not achieved after 12 weeks of the maximum dose, the weight loss pill should be gradually discontinued.

Daily doses with four strengths start at 3.75 mg/23 mg to 15 mg/92 mg. Side effects include abnormal sensations, dizziness, altered taste, insomnia, constipation, and dry mouth. Contraindications include uncontrolled hypertension and coronary artery disease, hyperthyroidism, glaucoma, and sensitivity to stimulants.

Naltrexone-bupropion (Contrave)

Naltrexone-bupropion combines an opioid receptor antagonist with an antidepressant to affect the pleasure-reward areas of the brain and thereby decrease cravings and appetite. Some patients may lose 5–10% of body weight.

Start with a daily dose of one 8/90 mg tablet and gradually increase to four tablets a day. The most common side effects include nausea, constipation, headache, vomiting, dizziness, insomnia, dry mouth, and diarrhea. This medication should not be prescribed to a patient who has a seizure disorder or who takes opioids for chronic pain.

Orlistat (Xenical and Alli)

Orlistat is a lipase inhibitor that comes in a capsule. It works by blocking the enzyme that breaks down fats consumed through food, inhibiting the absorption of dietary fats.

Undigested fat is then passed through the body. It is intended for use with a reduced-calorie diet and is also indicated to reduce the risk of weight regain.

Some patients may lose about 5% of their body weight. Dosage is one 120 mg capsule three times a day with each main meal containing fat (during or up to one hour after the meal).

An over-the-counter formulation is available at 60 mg capsules with each fat-containing meal. The most common adverse reactions to orlistat are oily discharge from the rectum, flatus with discharge, increased defecation, and fecal incontinence.

Setmelanotide (Imcivree)

Setmelanotide is a melanocortin-4 receptor agonist indicated for chronic weight management in adult and pediatric patients six years and older, with obesity due to certain rare genetic disorders. It is being studied for use in patients with acquired hypothalamic obesity.

The condition must be confirmed by genetic testing demonstrating variants in POMC, PCSK1, or LEPR genes that are interpreted as pathogenic, likely pathogenic, or of a variant of uncertain significance (VUS).

Hydrogel (Plenity)

A medical device rather than a medication, Plenity was FDA-cleared in 2019 for people with a BMI of 25 to 40. It consists of a capsule that releases a biodegradable, super-absorbent hydrogel into the stomach. The gel helps to increase satiety, enabling the person to eat less. The average weight loss in real-world studies is 9%.

More detailed information about each of the above weight loss medications can be found in the latest edition of Obesity Medicine Association’s Obesity Algorithm®.

Upcoming Weight Loss Medications

With fervent consumer demand for weight loss medications, combined with rising obesity rates, more medications are bound for the market in the coming years. Pharmaceutical platform Ozmosi predicts one to two GLP-1 launches annually starting in 2026. In May 2025, they reported 39 new GLP-1 medications in development.

Novo Nordisk is developing an oral version of semaglutide (50 mg) specifically for obesity. In the OASIS 1 Phase 3 trial, the oral formulation achieved an average weight loss of 15.1% over 68 weeks compared to 2.4% with placebo.

Lilly is developing at least two new options. The first, orforglipron, is an oral GLP-1 inhibitor that completed a Phase 3 clinical trial in early 2025. It could provide a welcome alternative for people who do not want injections. Phase 3 results expected soon. In Phase 2, orforglipron showed weight loss up to 14.7% at 36 weeks. The other, retatrutide, targets GLP-1, GIP, and glucagon. At this writing, it is in Phase 3 clinical trials. In Phase 2, participants lost up to 24.2% of body weight at 48 weeks. It is administered by injection.

Amgen is developing MariTide, a monoclonal antibody designed to increase GLP-1 receptor activity while reducing GIP receptor activity. The once-monthly injection entered Phase 3 clinical trials in March 2025. In a Phase 2 study, the medication showed up to 20% average weight loss at 52 weeks for people with obesity or overweight.

Researchers continue to study hormones that play a role in appetite for other ways to target obesity with medication. Those of interest include not only GLP-1, but also peptide tyrosine-tyrosine (PYY) and cholecystokinin (CCK).

With more options available, doctors will be increasingly able to personalize treatments. For more information on other emerging options, enroll in OMA’s course on Investigational Anti-Obesity Drugs in the Pipeline.

Frequently Asked Questions About Weight Loss Medications

How effective are weight loss medications?

FDA-approved anti-obesity medications (AOMs) are safe, evidence-based therapies that target specific physiology to improve the disease and are most effective when used as part of a comprehensive treatment plan. The amount of weight a person loses depends on the medication they take, their overall health, and other individual factors.

Even as the range of weight loss medications has expanded, some drugs have been withdrawn based on their lack of efficacy as well as safety concerns.

What is the strongest weight loss prescription medication?

Based on the latest clinical trials and real-world data, tirzepatide (Zepbound) currently stands out as the most effective FDA-approved prescription medication for weight loss.

In the SURMOUNT-1 trial, adults with obesity or overweight (without diabetes) taking tirzepatide achieved up to 22.5% average body weight reduction at 72 weeks. This surpasses the weight loss seen with semaglutide (Wegovy), which showed 14.9% average loss in the pivotal STEP 1 trial over a similar timeframe.

For comparison:

• Tirzepatide (Zepbound): Up to 22.5% average weight loss
• Semaglutide (Wegovy): Up to 14.9% average weight loss
• Liraglutide (Saxenda): ~8% average weight loss
• Phentermine-topiramate (Qsymia): 7–11% weight loss depending on dose
• Naltrexone-bupropion (Contrave): ~5–9% average weight loss

Tirzepatide is a dual GIP and GLP-1 receptor agonist that suppresses appetite, improves satiety, and supports metabolic health. In addition to impressive weight loss, studies show improvements in cardiovascular risk factors and metabolic markers. It was FDA-approved for obesity in November 2023 under the brand name Zepbound.

How do weight loss medications work?

They work primarily by regulating hormones in the brain, digestive system, and adipose tissue to suppress appetite and cravings and promote satiety.

Some medications are administered orally, and others are given as subcutaneous injections. Some patients who are less comfortable with injections may ask about weight-loss pills. Data released in May 2023, separately by Novo Nordisk and Pfizer, stated that pills and injections are about equally effective.

Are there medications that can cause weight gain?

There are many medications that can be obesogenic or cause weight gain. The following medications can potentially cause variable weight gain in some individuals.

• Some beta-blockers and calcium channel blockers
• Anti-diabetes medications such as insulins, sulfonylureas, thiazolidinediones, and meglitinides
• Hormone therapies such as glucocorticoids and injectable progestins
• Anti-seizure medications, including carbamazepine, gabapentin, valproate, and pregabalin
• A wide variety of different antidepressants
• Some mood stabilizers
• Migraine medications such as amitriptyline and paroxetine
• Some antipsychotics
• Chemotherapeutic and anti-inflammatory agents

How should weight loss medications be used in conjunction with other forms of treatment?

A treatment plan for obesity can comprise multiple forms of treatment, including medications, diet, exercise, and/or surgery. All weight loss medications work best in the context of a healthy eating plan and exercise. Even when a patient is engaging in exercise and other lifestyle adjustments, medications can help with hunger, cravings, and metabolic preservation.

How long do weight-loss medications need to be taken?

Some weight management medications are designed for short-term use and others for long-term use. For example, some are approved by the FDA for up to 12 weeks.

Those approved by the FDA for long-term use include orlistat (Xenical, Alli), phentermine-topiramate (Qsymia), naltrexone-bupropion (Contrave), liraglutide (Saxenda), semaglutide (Wegovy, Ozempic), and tirzepatide (Zepbound, Mounjaro). GLP-1s are not meant to be stopped and restarted at will. A patient who stops these may regain some or all of the weight.

The dosing for some of these includes a long ramp-up period—up to five months—to reach full dosage. Keep in mind that obesity is a disease, and no drug can permanently “cure” it.

How have options in weight loss medications changed in recent years?

While GLP-1s have grabbed a lot of headlines, they are only the latest in a long history of evolving weight loss medications. A 2022 article in Life Science explains:

“…as more physiological mechanisms for weight gain have been unearthed, drugs targeting newly discovered receptors and/or enzymes have been introduced with improved safety profiles and fewer psychological adverse events. Additionally, drugs targeting hunger or satiety signaling have been actively studied and have shown increased adoption by physicians. Studies have also evaluated drugs that target metabolic tissues—such as adipose tissue or muscle—to promote weight loss; however, to date, nothing has carried on into clinical practice.”

Undoubtedly, new candidates will continue to be developed, and some will come to market.

How do the different categories of weight loss medications compare in terms of cost?

As with many medications, some weight loss drugs have been on the market longer, have generic alternatives, and tend to be more affordable. GLP-1s are notoriously costly. The Kaiser Family Foundation estimates the annual net price of Wegovy at $13,600. According to GoodRx, phentermine can be had for as little as $10.

Direct Purchase Options

Both Wegovy and Zepbound are now available for eligible cash-paying patients—regardless of dose strength:

• NovoCare Pharmacy offers Wegovy (semaglutide) in all dose strengths via home delivery to uninsured or commercially insured individuals without obesity drug coverage.
• LillyDirect provides Zepbound (tirzepatide) single-dose vial access for the 7.5 mg, 10 mg, 12.5 mg, and 15 mg doses—starting with refill eligibility within 45 days of delivery. Supply for higher-dose prescriptions written as of July 7, 2025, is expected to begin in August 2025.

These programs apply only to self-pay patients and are not covered by insurance. They do not count toward deductibles or out-of-pocket maximums.

Insurance coverage varies and will affect many patients’ choices about going on weight loss medications. Medicare does not cover weight loss drugs.

How do they affect weight regain?

AOMs may counter the effects of metabolic adaptation and prevent weight regain. After weight reduction, the body metabolically adapts, often causing an increase in hunger hormones and a decrease in satiety hormones and resting metabolic rate, all of which can contribute to weight regain. If the patient achieves clinically meaningful weight reduction with anti-obesity medications and if the clinician and patient feel that the medication is helping to avoid weight regain, then a weight reduction plateau should not be considered a point where medication should be discontinued, but rather the medication should be continued for weight reduction maintenance.

What are the differences between OTC and prescription weight loss medications?

The only over-the-counter medicine for weight loss currently approved by the FDA is Alli (orlistat). Other over-the-counter products are considered supplements. They are not regulated by the FDA and do not have proper studies to confirm their safety and effectiveness.

With prescription medications, a healthcare professional can weigh all factors affecting the patient’s lifestyle and BMI and monitor progress and side effects. This relationship can allow for dosage adjustments or alternative medications if one seems like a better fit for the patient.

Can vitamins or supplements reduce belly fat?

While no specific vitamin or supplement is considered a “treatment” for obesity or overweight, certain ones help support metabolic health. For example, studies suggest that calcium and vitamin D may play a role in regulating belly fat. Various explanations have been proposed for how this works. Patients starting AOMs should tell their doctor about any vitamins or supplements they are taking.

What is the connection between antidepressant medication and weight loss?

Many antidepressants are weight-positive (cause weight gain), some are weight-neutral, and at least one is weight-negative (causes weight loss).

Antidepressants are broken down into categories: selective serotonin reuptake inhibitors (SSRIs), serotonin and norepinephrine reuptake inhibitors (SNRIs), tricyclic antidepressants, monoamine oxidase inhibitors (MAO inhibitors), and others.

In the SSRI group, paroxetine shows the highest associated weight gain. Other SSRIs, including citalopram (Celexa), escitalopram (Lexapro), fluoxetine (Prozac), and sertraline (Zoloft), have variable effects on weight, and some do not show weight gain until after six months of use.

Weight-positive medications in the tricyclic antidepressant category include amitriptyline, doxepin, and imipramine. Desipramine, nortriptyline, and protriptyline have variable effects on weight.

Bupropion (Wellbutrin), an aminoketone, is considered weight-negative and is prescribed both to assist in weight loss and to treat depression.

Which weight loss medications are known for suppressing appetite?

The following FDA-approved medications suppress appetite: tirzepatide (Zepbound), liraglutide (Saxenda), naltrexone-bupropion (Contrave), phentermine-topiramate (Qysmia), as well as these stimulants: benzphetamine (Didrex™), diethylpropion (Tenuate™), phentermine (Adipex-P, ProFast), and phendimetrazine. Each medicine impacts appetite differently.

What qualifies someone for weight loss medication?

The guidelines for tirzepatide (Zepbound) and semaglutide (Wegovy) state that a patient should have a BMI of 30 or a BMI of 27 with weight-related health problems. They can also interfere with hormonal birth control. Older AOMs also have indications based on BMI and may be contraindicated for use with certain other medications. None are approved for use in someone who is pregnant.

What are “counterfeit” GLP-1s?

Some online healthcare providers claim to sell Ozempic, Wegovy, or Zepbound at reduced prices. However, the FDA warns against buying medications from any source other than a state-licensed pharmacy. In April 2025, they banned the sale of “counterfeit” semaglutide and tirzepatide. These medications are not made or packaged by the original manufacturers. Instead, they are compounded medications. They may contain the same active ingredient (e.g., semaglutide or tirzepatide) but—the FDA warns—“could contain the wrong ingredients, contain too little, too much, or no active ingredient at all or other harmful ingredients…”

Are compounded weight loss medications safe and effective?

Compounded versions of medications are made by compounding pharmacies, often to tailor a medication to specific patient needs, like an allergy to an inactive ingredient. Compounded medications are not FDA-approved. For about two years, compounded versions of semaglutide and tirzepatide were permitted in the U.S. due to shortages. Some patients have taken these alternatives, which are generally more affordable, without ill effects. However, the FDA has received 520 reports of adverse events associated with compounded semaglutide and 480 reports of adverse events associated with compounded tirzepatide (as of April 30, 2025). Patient and doctors should always discuss the potential risks and potential benefits as they relate to that patient’s unique situation.

Are you seeking obesity treatment? Find an obesity medicine specialist near you who can assist in finding the best weight loss medications for you.

Weight Loss Medications At a Glance

Drug name	Brand name(s)	Approved for	How it’s administered	Frequency
Semaglutide	Wegovy, Ozempic	Adults, Children 12+	Injection	Once weekly
Tirzepatide	Zepbound, Mounjaro	Adults	Injection	Once weekly
Liraglutide	Saxenda	Adults, Children 12+	Injection	Once daily
Phentermine	Adipex, Suprenza, Lomaira	Age 17+	Tablet, capsule, or ODT	Daily (Lomaira 3x/day)
Phentermine-topiramate	Qsymia	Adults, Children 12+	Capsule	Once daily
Naltrexone-bupropion	Contrave	Adults	Tablet	Once or twice daily
Orlistat	Xenical, Alli	Adults, Children 12+	Capsule	3x/day
Setmelanotide	Imcivree	Adults, Children 6+ (only with certain rare genetic disorders)	Injection	Once daily
Hydrogel	Plenity (Note: This is an FDA-approved medical device, not a medication)	Adults	Capsule	Twice daily