Product Code Database
Anti-obesity medication or weight loss medications are pharmacological agents that reduce excess body fat and cause weight loss. These alter one of the fundamental processes of body weight regulation, by: anorectic and consequently energy intake, increasing energy expenditure, redirecting nutrients from adipose to lean tissue, or interfering with the absorption of calories.
Weight loss drugs have been developed since the early twentieth century, and many have been banned or withdrawn from the market due to adverse effects, including deaths; other drugs proved ineffective. Although many earlier drugs were stimulants such as amphetamines, in the early 2020s, GLP-1 receptor agonists became popular for weight loss.
As of 2023, the medications liraglutide, naltrexone/bupropion, orlistat, semaglutide, tirzepatide and phentermine/topiramate are approved by the US Food and Drug Administration (FDA) for weight management in combination with reduced-calorie diet and increased physical activity. Medications to treat obesity may be considered in those with a body mass index above 30, or above 27 with obesity related complications (such as hypertension, hyperlipidemia, cardiovascular disease, or obstructive sleep apnea). As of 2022, no medication has been shown to be as effective at long-term weight reduction as bariatric surgery.
Amphetamines (marketed as Benzedrine) became popular for weight loss during the late 1930s. They worked primarily by suppressing appetite, and had other beneficial effects such as increased alertness. Use of amphetamines increased over the subsequent decades, including Obetrol and culminating in the "rainbow diet pill" regime. This was a combination of multiple pills, all thought to help with weight loss, taken throughout the day. Typical regimens included stimulants, such as amphetamines, as well as thyroid hormone, , digitalis, laxatives, and often a barbiturate to suppress the side effects of the stimulants. In 1967/1968 a number of deaths attributed to diet pills triggered a Senate investigation and the gradual implementation of greater restrictions on the market. While rainbow diet pills were banned in the US in the late 1960s, they reappeared in South America and Europe in the 1980s. In 1959, phentermine had been FDA approved and fenfluramine in 1973. In the early 1990s two studies found that a combination of the drugs was more effective than either on its own; fen-phen became popular in the United States and had more than 18 million prescriptions in 1996. Evidence mounted that the combination could cause valvular heart disease in up to 30 percent of those who had taken it, leading to withdrawal of fen-phen and dexfenfluramine from the market in September 1997.
In the early 2020s, GLP-1 receptor agonists such as semaglutide (Ozempic, Wegovy) or tirzepatide (Zepbound) became popular for weight loss because they are more effective than earlier drugs, causing a shortage for patients prescribed these medications for type 2 diabetes, their original indication. After the FDA approved semaglutide and tirzepatide for chronic weight management, GLP-1 medications became available through various virtual weight loss programs. GLP-1 receptor agonists are associated with reduced riks of cardiovascular events (such as heart attack and stroke) in adults with obesity.
The American Academy of Pediatrics had not previously supported the use of weight loss medication in adolescents but issued new guidelines in 2023, which recommend considering the use of weight loss medication in some overweight children aged 12 or older. The European Medicines Agency has approved semaglutide for children aged 12 or older who have a BMI in the 95 percentile for their age and a weight of at least . However, GLP-1 agonists may not be cost effective in this population.
As of 2022, no medication has been discovered that would equal the effectiveness of bariatric surgery for long-term weight loss and improved health outcomes.
After stopping treatment with GLP-1 agonists such as semaglutide, liraglutide and tirzepatide, people regain on average more than half (50–70%) of the lost weight within 1 year.
Patient population
The United States Food and Drug Administration and the European Medicines Agency have approved weight loss medications for adults with either a body-mass index (BMI) of at least 30, or a body-mass index of at least 27 with at least one weight-related comorbidity. This patient population is considered to have sufficiently high baseline health risks to justify the use of anti-obesity medication.
Medication
US FDA approved
The US Food and Drug Administration (FDA) approves anti-obesity medications as an adjunctive therapy to diet and exercise for people for whom lifestyle changes do not result in sufficient weight loss. In the United States, semaglutide (Wegovy) is approved by the FDA for chronic weight management. The FDA guidelines say that a therapy may be approved if it results in weight loss that is statistically significant greater than placebo and generally at least five percent of body weight over six months that comes predominantly from fat mass. Some other prescription weight loss medications are stimulants, which are recommended only for short-term use, and thus are of limited usefulness for patients who may need to reduce weight over months or years. As of 2022, there is no pathway for approval for drugs that reduce fat mass without 5 percent overall weight loss, even if they significantly improve metabolic health; neither is there one for drugs that help patients maintain weight loss although this can be more challenging than losing weight.
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!Medication Name
!Trade name(s)
!Mechanism of action
!Current FDA Status
!placebo-adjusted percent bodyweight lost (highest dose studied) Semaglutide Wegovy, Ozempic GLP-1 receptor agonist Approved for weight management (chronic) 12% Phentermine/topiramate Qsymia Phentermine is a substituted amphetamine and topiramate has an unknown mechanism of action Approved for weight management (short-term) by the FDA but not the European Medicines Agency 10% or Naltrexone/bupropion Contrave Reduces food cravings by inhibiting the mesolimbic system via activation of proopiomelanocortin neurons in the hypothalamus. Approved for weight management (chronic) in the US and EU 5 percent Liraglutide Saxenda GLP-1 receptor agonist Approved for weight management (chronic) 4 percent Gelesis100 (medical device) Plenity Oral hydrogel FDA approved for weight management (chronic) but the American Gastroenterology Association recommends that its use be limited to clinical trials due to lack of evidence. 2% Orlistat Xenical Absorption inhibitor Approved for weight management (chronic) ; percentage not provided Phentermine Adipex Substituted amphetamine Approved for weight management (short-term) Tirzepatide Mounjaro/
Zepbound Dual GLP-1 receptor agonist and GIP agonist Approved for weight management (chronic) 18.4 percent
Withdrawn
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!Medication Name
!Trade name(s)
!Mechanism of action
!Current FDA Status
!placebo-adjusted percent bodyweight lost (highest dose studied) Lorcaserin Belviq 5-HT2C receptor agonist Withdrawn for safety reasons 6.25 percent Sibutramine Meridia Serotonin–norepinephrine reuptake inhibitor Withdrawn due to cardiovascular risks 19.7 percent Rimonabant Acomplia, Zimulti Cannabinoid receptor antagonist Withdrawn for safety reasons Fenfluramine Fintepla, Pondimin Serotonin releasing agent Withdrawn for safety reasons - Fenfluramine/phentermine (fen-phen) Pondimin Withdrawn for safety reasons 13.9 percent Dexfenfluramine Redux Serotonin releasing agent Withdrawn for safety reasons 2,4-Dinitrophenol Uncoupling agent Withdrawn for safety reasons per patient on average (uncontrolled study)
Ephedrine Adrenergic agonist Approved for asthma Average of in a meta-analysis (all dosages) ECA stack Combination of ephedrine and caffeine, sometimes adding aspirin Around Ephedra Plant extract sold as a dietary supplement Contains ephedrine, an adrenergic agonist Banned in 2004 for safety reasons per month more than placebo (2025). 9783319182308, Springer International Publishing. ISBN 9783319182308Amphetamine salts Obetrol Approved 1960, withdrawn 1973; Adderall was later approved for ADHD and narcolepsy and is still used for those purposes Phenylpropanolamine Was an over-the-counter medication ingredient Withdrawn in 2005 due to risk of hemorragic stroke
Never approved or not currently approved
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!Medication Name
!Trade name(s)
!Mechanism of action
!Current FDA Status
!placebo-adjusted percent bodyweight lost (highest dose studied) Retatrutide GLP-1, GIP receptor, and glucagon receptor triple agonist In clinical trials 24 percent in a Phase II trial Free access subject to registration. Exenatide Byetta GLP-1 receptor agonist Approved for type 2 diabetes Cetilistat Absorption inhibitor Not approved Tesofensine (NS2330) Serotonin–norepinephrine–dopamine reuptake inhibitor Not FDA approved 10.6 percent
Metformin Glucophage Unknown Approved for type 2 diabetes 5.6 percent Cagrilintide Dual amylin and calcitonin receptor agonist (DACRA) Not approved 7.8 percent Cagrilintide/semaglutide CagriSema DACRA/GLP-1 agonist combination Not approved 20.4 percent in phase III trial
Safety and side effects
Some anti-obesity medications can have severe, even lethal side effects, fen-phen being a famous example. Fen-phen was reported through the FDA to cause abnormal echocardiograms, heart valve problems, and rare valvular diseases. Out of 25 anti-obesity medications withdrawn from the market between 1964 and 2009, 23 acted by altering the functions of chemical neurotransmitters in the brain. The most common side effects of these drugs that led to withdrawals were mental disturbances, cardiac side effects, and Substance abuse or drug dependence. Deaths were associated with seven products. Ephedra was removed from the US market in 2004 over concerns that it raises blood pressure and could lead to strokes and death.
Weight regain
Weight regain is common upon discontinuation of weight loss medications, and long-term therapy may sometimes be required for sustained weight loss.
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