Anti-obesity drugs

Anti-obesity drugs ;
Synonyms	Weight loss medications, obesity pharmacotherapy, anti-obesity medications
Specialty	Obesity medicine, endocrinology, primary care, bariatric medicine
Uses	Obesity, overweight, weight management, weight loss
Types	GLP-1 receptor agonists, GIP and GLP-1 receptor agonists, appetite suppressants, fat absorption inhibitors, combination drugs, melanocortin-4 receptor agonists ; ; ; ; ;

Medications used to treat obesity and overweight as part of medical weight loss care

Anti-obesity drugs are medications used to help people with obesity or overweight lose weight, maintain weight loss, and reduce obesity-related health risks. They may work by reducing appetite, increasing the feeling of satiety or fullness, slowing gastric emptying, altering neurohormonal signals involved in hunger, improving insulin resistance, or decreasing absorption of dietary fat. Anti-obesity drugs are usually prescribed together with a reduced-calorie diet, physical activity, behavioral counseling, and long-term weight management follow-up.

Modern obesity medicine includes both newer injectable incretin therapies, such as semaglutide and tirzepatide, and traditional oral weight loss medications, such as phentermine, orlistat, phentermine/topiramate, and naltrexone/bupropion. Some drugs are approved for long-term chronic weight management, while older sympathomimetic drugs are generally approved only for short-term use.

Overview

Obesity is a chronic, relapsing, multifactorial medical condition involving energy balance, genetics, hormones, appetite regulation, sleep, stress, physical activity, food environment, and metabolism. Anti-obesity drugs are not simply cosmetic treatments; they are medical therapies intended for selected patients whose excess weight increases the risk of conditions such as type 2 diabetes, high blood pressure, dyslipidemia, sleep apnea, fatty liver disease, osteoarthritis, polycystic ovary syndrome, and cardiovascular disease.

The United States Food and Drug Administration has approved several medications for chronic weight management, including orlistat, phentermine/topiramate, naltrexone/bupropion, liraglutide, semaglutide, and tirzepatide.Prescription Medications to Treat Overweight & Obesity(link). National Institute of Diabetes and Digestive and Kidney Diseases.Accessed 2026-06-24. Setmelanotide is also approved for selected rare genetic or hypothalamic forms of obesity and is not a general obesity medication for typical polygenic obesity.FDA approves first treatment for weight management in people with certain rare genetic conditions(link). United States Food and Drug Administration.2020-11-27.Accessed 2026-06-24.

Who may be considered for anti-obesity drugs

Anti-obesity medications are commonly considered for adults with:

Body mass index of 30 kg/m² or higher, also called obesity.
Body mass index of 27 kg/m² or higher with at least one weight-related condition, such as type 2 diabetes, hypertension, dyslipidemia, obstructive sleep apnea, fatty liver, or cardiovascular disease.
Prior difficulty achieving or maintaining clinically meaningful weight loss with diet, exercise, and lifestyle changes alone.
Medical need for structured weight management supervised by a qualified healthcare professional.

Medication selection depends on the patient’s medical history, current medication list, blood pressure, heart disease risk, kidney disease, liver disease, diabetes, sleep apnea, pregnancy status, insurance coverage, prior side effects, and weight loss goals.

Major types of anti-obesity drugs

GLP-1 receptor agonists

GLP-1 receptor agonists mimic the hormone glucagon-like peptide-1, which helps regulate blood glucose, insulin, glucagon, appetite, and satiety. These medications may reduce hunger, help patients feel full sooner, slow gastric emptying, and improve glycemic control.

FDA-approved GLP-1-based weight loss drugs include:

Liraglutide 3 mg injection, marketed as Saxenda, a once-daily GLP-1 receptor agonist approved for chronic weight management.
Semaglutide injection, marketed as Wegovy, a once-weekly GLP-1 receptor agonist approved for chronic weight management. The FDA approved Wegovy in 2021 for chronic weight management in adults with obesity or overweight with at least one weight-related condition.FDA approves new drug treatment for chronic weight management, first since 2014(link). United States Food and Drug Administration.2021-06-04.Accessed 2026-06-24.
Wegovy HD, a higher-dose semaglutide injection approved by the FDA in 2026 for weight loss and long-term maintenance in certain adult patients.FDA Approves Fourth Product Under National Priority Voucher Program: Higher Dose Semaglutide(link). United States Food and Drug Administration.2026-03-19.Accessed 2026-06-24.
Wegovy tablet, an oral semaglutide formulation reflected in FDA labeling updates for Wegovy tablets.WEGOVY tablet prescribing information(link). United States Food and Drug Administration.2026.Accessed 2026-06-24.

Common side effects of GLP-1 receptor agonists include nausea, vomiting, diarrhea, constipation, abdominal pain, reflux, and reduced appetite. Less common but clinically important risks may include gallbladder disease, pancreatitis, dehydration, worsening gastroparesis, and medication interactions related to delayed stomach emptying.

Dual GIP and GLP-1 receptor agonists

Tirzepatide, marketed for weight loss as Zepbound, is a dual GIP and GLP-1 receptor agonist. It activates both the glucose-dependent insulinotropic polypeptide receptor and the GLP-1 receptor, helping reduce appetite, improve fullness, and support weight reduction.

The FDA approved Zepbound for chronic weight management in adults with obesity or with overweight and at least one weight-related condition, in addition to a reduced-calorie diet and increased physical activity.FDA Approves New Medication for Chronic Weight Management(link). United States Food and Drug Administration.2023-11-08.Accessed 2026-06-24. In 2024, the FDA also approved Zepbound for adults with obesity and moderate-to-severe obstructive sleep apnea, making it the first FDA-approved medication for that sleep-related indication.FDA Approves First Medication for Obstructive Sleep Apnea(link). United States Food and Drug Administration.2024-12-20.Accessed 2026-06-24.

Mounjaro is the brand name of tirzepatide approved for type 2 diabetes, while Zepbound is the brand name used for chronic weight management and obesity-related indications.

Traditional appetite suppressants

Traditional appetite suppressants include older sympathomimetic amine drugs that stimulate pathways related to norepinephrine and appetite control. These medications are generally intended for short-term use and require careful monitoring.

Examples include:

These drugs may reduce hunger and improve adherence to a low-calorie diet, but they can increase heart rate, blood pressure, insomnia, anxiety, dry mouth, and palpitations. They are usually avoided or used with caution in patients with uncontrolled hypertension, significant heart disease, certain arrhythmias, hyperthyroidism, glaucoma, or a history of medication misuse.

Fat absorption inhibitors

Orlistat is a fat absorption inhibitor that works in the gastrointestinal tract by inhibiting pancreatic lipase and reducing absorption of dietary triglyceride fat. Prescription orlistat is marketed as Xenical, while lower-dose over-the-counter orlistat is marketed as Alli.

Because orlistat reduces fat absorption, it can cause oily stool, flatulence, fecal urgency, and diarrhea, especially after high-fat meals. It can also reduce absorption of fat-soluble vitamins, including vitamin A, vitamin D, vitamin E, and vitamin K, so patients are often advised to take a multivitamin at a separate time of day.

Combination drugs

Combination anti-obesity drugs use more than one mechanism to improve weight loss.

Common examples include:

Phentermine/topiramate, marketed as Qsymia, combines the appetite-suppressing effect of phentermine with topiramate, a medication that may affect appetite, cravings, and satiety.
Naltrexone/bupropion, marketed as Contrave, combines naltrexone, an opioid receptor antagonist, with bupropion, a dopamine and norepinephrine reuptake inhibitor, to affect reward-driven eating and appetite regulation.

These medications have specific contraindications. Qsymia can cause birth defects and requires pregnancy precautions in patients who can become pregnant. Contrave carries warnings related to seizure risk, blood pressure, suicidal thoughts, and use with opioid medications.

Melanocortin-4 receptor agonists

Setmelanotide, marketed as Imcivree, is a melanocortin-4 receptor agonist used for specific rare obesity disorders involving the MC4R pathway. It is not a routine medication for common obesity. It has been approved for chronic weight management in selected genetic obesity conditions such as POMC deficiency, PCSK1 deficiency, LEPR deficiency, and Bardet-Biedl syndrome, and the FDA has also approved expanded use for acquired hypothalamic obesity.FDA approves first treatment for weight management in people with certain rare genetic conditions(link). United States Food and Drug Administration.2020-11-27.Accessed 2026-06-24.Rhythm Pharmaceuticals Announces FDA Approval of IMCIVREE for Patients with Acquired Hypothalamic Obesity(link). Rhythm Pharmaceuticals.2026-03-19.Accessed 2026-06-24.

FDA-approved anti-obesity drugs in the United States

The following table summarizes major FDA-approved drugs used for weight management in the United States. Exact indications, age limits, contraindications, dosing, and insurance coverage may change and should be verified from current prescribing information.

Drug or brand	Generic name	Drug class	Usual role in obesity care	Notes
Wegovy	Semaglutide	GLP-1 receptor agonist	Chronic weight management	Weekly injection; FDA-approved for chronic weight management; also approved to reduce risk of major cardiovascular events in certain adults with cardiovascular disease and obesity or overweight.FDA Approves First Treatment to Reduce Risk of Serious Heart Problems Specifically in Adults with Obesity or Overweight(link). United States Food and Drug Administration.2024-03-08.Accessed 2026-06-24.
Wegovy HD	Semaglutide	GLP-1 receptor agonist	Higher-dose chronic weight management	Higher-dose semaglutide injection approved in 2026 for selected adult patients.FDA Approves Fourth Product Under National Priority Voucher Program: Higher Dose Semaglutide(link). United States Food and Drug Administration.2026-03-19.Accessed 2026-06-24.
Zepbound	Tirzepatide	Dual GIP/GLP-1 receptor agonist	Chronic weight management	Weekly injection; also FDA-approved for moderate-to-severe obstructive sleep apnea in adults with obesity.FDA Approves First Medication for Obstructive Sleep Apnea(link). United States Food and Drug Administration.2024-12-20.Accessed 2026-06-24.
Saxenda	Liraglutide	GLP-1 receptor agonist	Chronic weight management	Daily injection; used for weight management in adults and certain adolescents.
Qsymia	Phentermine/topiramate	Combination medication	Chronic weight management	Oral medication combining phentermine and topiramate.
Contrave	Naltrexone/bupropion	Combination medication	Chronic weight management	Oral medication affecting appetite and reward-related eating pathways.
Xenical	Orlistat	Fat absorption inhibitor	Chronic weight management	Prescription-strength orlistat.
Alli	Orlistat	Fat absorption inhibitor	Over-the-counter weight loss aid	Lower-dose orlistat available without prescription.
Phentermine	Phentermine	Appetite suppressant	Short-term weight loss treatment	Traditional sympathomimetic appetite suppressant; requires monitoring of blood pressure, heart rate, and contraindications.
Phendimetrazine	Phendimetrazine	Appetite suppressant	Short-term weight loss treatment	Traditional sympathomimetic appetite suppressant.
Diethylpropion	Diethylpropion	Appetite suppressant	Short-term weight loss treatment	Traditional sympathomimetic appetite suppressant.
Benzphetamine	Benzphetamine	Appetite suppressant	Short-term weight loss treatment	Traditional sympathomimetic appetite suppressant.
Imcivree	Setmelanotide	Melanocortin-4 receptor agonist	Rare genetic or hypothalamic obesity	Not for common polygenic obesity; used for specific rare obesity disorders.

GLP-1 and incretin-based weight loss injections

The most important recent change in anti-obesity medicine is the rise of incretin-based therapy. These drugs are often called “GLP-1 weight loss injections” by patients, although not all of them are pure GLP-1 drugs.

Semaglutide

Semaglutide is a GLP-1 receptor agonist. For weight management, it is best known as Wegovy. Semaglutide promotes weight loss by increasing satiety, reducing appetite, and slowing stomach emptying. It is also used in other formulations for type 2 diabetes, such as Ozempic and Rybelsus, but those diabetes brands are not the same as Wegovy for obesity treatment.

Tirzepatide

Tirzepatide is a dual GIP/GLP-1 receptor agonist. It is marketed as Zepbound for weight management and as Mounjaro for type 2 diabetes. Zepbound is one of the most effective approved pharmacologic options for chronic weight management and is especially relevant at W8MD because many patients with obesity also have insulin resistance, prediabetes, type 2 diabetes, or sleep apnea.

Liraglutide

Liraglutide is a daily GLP-1 receptor agonist marketed as Saxenda for obesity treatment. It is an earlier GLP-1 medication and may still be considered when clinically appropriate, depending on patient profile, availability, insurance, and tolerance.

Traditional diet pills

Traditional weight loss medications still have a role in obesity care, especially when GLP-1 access is limited by insurance coverage, cost, supply, contraindications, or side effects.

Phentermine

Phentermine is one of the oldest and most widely used prescription weight loss drugs in the United States. It is an appetite suppressant that may help reduce hunger and improve adherence to a low-calorie diet. It is generally used short-term and requires monitoring of blood pressure, heart rate, sleep, mood, and side effects.

Phendimetrazine and diethylpropion

Phendimetrazine and diethylpropion are traditional appetite suppressants. They may be considered in selected patients but are not suitable for everyone, especially those with uncontrolled hypertension, heart disease, or certain psychiatric or substance-use histories.

Orlistat

Orlistat is different from appetite suppressants because it works in the gut by reducing absorption of dietary fat. It may be useful for some patients who prefer a non-stimulant option, but gastrointestinal side effects often limit adherence.

Qsymia

Qsymia combines phentermine and topiramate. It can produce greater weight loss than phentermine alone but requires careful review of contraindications, pregnancy risk, mood effects, cognitive side effects, and medication interactions.

Contrave

Contrave combines naltrexone and bupropion. It may be helpful for appetite, cravings, and reward-driven eating in selected patients, but it should not be used with chronic opioid therapy and requires attention to seizure risk, mood history, and blood pressure.

Emerging and investigational anti-obesity drugs

Several emerging obesity medications are under development. These drugs may become important future options, but they should not be described as FDA-approved until approval has occurred.

Retatrutide

Retatrutide, sometimes misspelled as Ritatrutide, is an investigational triple-hormone receptor agonist that targets GIP, GLP-1, and glucagon receptor pathways. In a phase 2 trial published in The New England Journal of Medicine, retatrutide produced substantial body-weight reductions in adults with obesity, including a mean weight reduction of 24.2% at 48 weeks in the 12-mg dose group.Jastreboff, A. M.."Triple–Hormone-Receptor Agonist Retatrutide for Obesity".The New England Journal of Medicine.2023;doi:10.1056/NEJMoa2301972.Full text. Retatrutide remains investigational for obesity unless and until it receives FDA approval.

Orforglipron

Orforglipron is an investigational oral GLP-1 receptor agonist being studied for obesity and type 2 diabetes. If approved, oral incretin therapy may expand options for patients who prefer to avoid injections.

CagriSema

CagriSema is an investigational combination of cagrilintide, an amylin analog, and semaglutide, a GLP-1 receptor agonist. It is being studied for chronic weight management and may become part of future combination incretin-based obesity treatment.

Other pipeline approaches

Other investigational approaches include:

Amylin analogs that increase satiety.
Glucagon receptor combinations that may increase energy expenditure.
Oral incretin therapies.
Newer multi-agonist peptides targeting GLP-1, GIP, glucagon, or related metabolic pathways.
Drugs designed for specific genetic, hypothalamic, or neuroendocrine causes of obesity.

Benefits of anti-obesity drugs

Potential benefits of anti-obesity medications include:

Reduced appetite and food cravings.
Increased satiety after meals.
Greater adherence to a reduced-calorie diet.
Improved weight loss compared with lifestyle treatment alone.
Improved blood glucose in patients with prediabetes or type 2 diabetes.
Lower blood pressure in some patients after weight loss.
Improvement in dyslipidemia.
Improvement in fatty liver markers for some patients.
Reduced waist circumference and visceral fat.
Improvement in obesity-related sleep apnea for some patients, especially with clinically meaningful weight loss.
Reduced long-term risk of some obesity-related complications.

Risks and side effects

Anti-obesity drugs can cause side effects and must be matched to the patient’s medical history.

Common risks and adverse effects may include:

Nausea, vomiting, diarrhea, constipation, and abdominal pain, especially with GLP-1 receptor agonists and tirzepatide.
Dehydration or worsening kidney function if vomiting or diarrhea is severe.
Gallstones or gallbladder disease during rapid weight loss.
Possible pancreatitis risk in susceptible patients.
Increased heart rate or blood pressure with stimulant appetite suppressants.
Insomnia, anxiety, dry mouth, or palpitations with sympathomimetic medications.
Oily stool, fecal urgency, and reduced absorption of fat-soluble vitamins with orlistat.
Mood changes or suicidal ideation warnings with some medications.
Potential medication interactions, including interactions with opioid therapy for naltrexone/bupropion.
Pregnancy-related concerns, especially with phentermine/topiramate, which requires strict pregnancy precautions.

Patients should seek urgent medical care for severe abdominal pain, signs of pancreatitis, symptoms of allergic reaction, severe dehydration, chest pain, fainting, suicidal thoughts, or other serious symptoms.

Contraindications and cautions

Anti-obesity medications may not be appropriate for everyone. Contraindications and cautions vary by drug but may include:

Pregnancy or plans for pregnancy.
Personal or family history of certain endocrine tumors, depending on the medication.
Severe gastrointestinal disease or gastroparesis.
Uncontrolled hypertension.
Significant cardiovascular disease.
Glaucoma.
Hyperthyroidism.
History of seizure disorder.
Current chronic opioid use.
Severe kidney disease or liver disease.
History of eating disorder, depending on the medication and clinical context.
Use of interacting drugs such as monoamine oxidase inhibitors.

Lifestyle treatment remains essential

Anti-obesity drugs work best when combined with structured lifestyle treatment. Core elements include:

A personalized reduced-calorie diet.
Adequate protein intake to preserve lean body mass.
Portion control and food journal tracking.
Low-carbohydrate diet, Mediterranean diet, high-protein diet, or very-low-calorie diet when clinically appropriate.
Meal replacement plans for selected patients.
Regular physical activity, including aerobic exercise and strength training.
Improved sleep hygiene and treatment of sleep apnea.
Stress management and behavioral support for emotional eating.
Long-term follow-up to prevent weight regain.

How W8MD Weight Loss, Sleep and Medspa can help

W8MD Weight Loss, Sleep and Medspa centers provide physician-supervised medical weight loss care for patients with obesity, overweight, insulin resistance, prediabetes, type 2 diabetes, PCOS, sleep apnea, and other weight-related conditions. W8MD can help patients understand whether anti-obesity medication is appropriate and which option best fits their medical history, goals, insurance, and budget.

Services may include:

Comprehensive medical weight loss evaluation.
Measurement of body mass index, waist circumference, weight history, and obesity-related risk factors.
Screening for type 2 diabetes, prediabetes, insulin resistance, thyroid disease, fatty liver, sleep apnea, and other conditions.
Prescription of FDA-approved anti-obesity medications when medically appropriate.
Access to GLP-1 and incretin-based options such as semaglutide, Wegovy, tirzepatide, and Zepbound when clinically indicated and available.
Traditional medications such as phentermine, topiramate, phentermine/topiramate, Contrave, orlistat, or other options when appropriate.
Prior authorization support for insurance-covered anti-obesity drugs.
Guidance for patients who do not have medication coverage or who need self-pay alternatives.
Structured low-calorie diet, very-low-calorie diet, low-carbohydrate diet, high-protein diet, and meal replacement plans.
Protein shakes, meal replacements, B12 shots, Lipo B shots, and nutritional support when appropriate.
Home sleep study testing and treatment pathways for obstructive sleep apnea.
Integration of weight loss and sleep care, especially for patients whose obesity contributes to snoring, sleep apnea, fatigue, or metabolic problems.
Long-term monitoring for side effects, medication tolerance, weight plateaus, and weight maintenance.
Medical aesthetics, microneedling, oxygen facials, and medspa services for selected patients seeking supportive aesthetic care during or after weight loss.

W8MD emphasizes that anti-obesity medication is not a substitute for lifestyle change. Instead, medication is used as part of a supervised plan that combines nutrition, physical activity, sleep medicine, behavioral support, and medical monitoring.

Monitoring during treatment

Patients taking anti-obesity drugs should be followed regularly to assess:

Weight, body mass index, and waist circumference.
Blood pressure and heart rate.
Side effects and medication tolerance.
Blood glucose, A1C, and diabetes medication needs.
Lipid profile and metabolic risk.
Kidney function and liver function when indicated.
Symptoms of sleep apnea, insomnia, or fatigue.
Adequate intake of protein, fiber, vitamins, and minerals.
Need for dose adjustment, medication change, or discontinuation.

Stopping or changing medication

Anti-obesity medications may be stopped or changed if:

The medication is ineffective after an adequate trial.
Side effects are intolerable.
A contraindication develops.
The patient becomes pregnant or plans pregnancy.
Insurance coverage changes.
A safer or more effective medication becomes available.
The patient reaches a maintenance phase and chooses a different long-term plan.

Because weight regain is common after stopping medication, discontinuation should usually be paired with a maintenance plan that includes dietary management, physical activity, sleep optimization, and follow-up.

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