Almost All Weight Loss Drugs (Good, Bad and Awful) Ever Used in the United States

Tapeworm Egg: While not actually a drug, a tapeworm egg in a sugar cube was sold and ingested as if it was a drug and so I will list it here. Tapeworm eggs were used in the early 20th century as a weight loss aid. The eggs were ingested, and the tapeworms would grow inside the host's intestines, consuming nutrients and calories. This method is not only dangerous but also illegal in the US. Side effects include abdominal pain, malnutrition, and in severe cases, organ damage and death.

Dinitrophenol (DNP): DNP is an industrial chemical that was discovered in the 1930s to cause rapid weight loss by uncoupling oxidative phosphorylation in cells, increasing metabolic rate. It was banned in the US in 1938 due to its severe side effects, including cataracts, skin lesions, and fatalities due to hyperthermia. DNP remains illegal and is not used in medical practice.

Amphetamines: Amphetamines were widely prescribed as appetite suppressants in the 1950s and 1960s. They work by increasing the release of certain neurotransmitters, such as dopamine, which suppress appetite. However, their use declined due to the risk of addiction and side effects like insomnia, increased heart rate, and high blood pressure. Currently, amphetamines are not approved for weight loss in the US.

Phentermine is the most widely prescribed weight loss drug on Earth. Since it was first approved by the US FDA in 1959, phentermine is estimated to have been prescribed to over half a billion people on Earth. Phentermine is a mainstay of what we call "classic" weight loss drugs. It works very well for most people and extremely well for some. Phentermine is a stimulant and therefore may cause related side effects but these are usually mild and easily managed through dose modulation.

Phendimetrazine: Phendimetrazine is another sympathomimetic amine approved for short-term use as an appetite suppressant. It works similarly to phentermine and was approved by the FDA in 1961. Side effects include dizziness, dry mouth, and increased heart rate.

Diethylpropion: Diethylpropion, approved in 1959, is a sympathomimetic amine used for short-term treatment of obesity. It reduces appetite and boosts metabolism. Side effects include dizziness, headache, and insomnia.

Preludin (phenmetrazine): Preludin was an amphetamine-like drug used as an appetite suppressant in the 1960s. However, it was discontinued due to its potential for abuse and addiction.

Didrex (benzphetamine): Didrex, an anorectic drug, was approved in 1960. It stimulates the central nervous system, suppressing appetite. Side effects include elevated blood pressure, dry mouth, and constipation. Didrex is available by prescription in the US.

Fenfluramine (Pondimin) and Dexfenfluramine (Redux): Fenfluramine and its enantiomer dexfenfluramine were approved in the 1970s and 1990s, respectively. They worked by increasing serotonin levels, reducing appetite. However, both were withdrawn from the US market in 1997 due to their association with serious heart and lung issues, including primary pulmonary hypertension and valvular heart disease.

Phenylpropanolamine (Dexatrim): Phenylpropanolamine was an over-the-counter weight loss ingredient found in products like Dexatrim. It was removed from the US market in 2000 due to its association with an increased risk of hemorrhagic stroke.

Sanorex (mazindol): Sanorex, approved in the 1970s, is a sympathomimetic amine that suppresses appetite. It is rarely prescribed due to concerns about its potential for abuse and side effects, including high blood pressure, dry mouth, and constipation.

Rimonabant: Rimonabant is a selective cannabinoid-1 receptor antagonist that was never approved in the US. It was used in Europe for a short time but was withdrawn due to its association with psychiatric side effects, including depression and suicidal thoughts.

Xenical (orlistat) and Alli: Xenical (prescription) and Alli (over-the-counter) are FDA-approved weight loss medications that work by inhibiting the absorption of dietary fat. Side effects include oily stools, gas, and abdominal pain. Alli and Xenical are available in the US.

Meridia (sibutramine): Meridia was approved in 1997 and worked by increasing serotonin, norepinephrine, and dopamine levels, reducing appetite. It was withdrawn from the US market in 2010 due to an increased risk of cardiovascular events.

Topiramate: Topiramate is an anticonvulsant medication that is sometimes prescribed off-label for weight loss. It works by suppressing appetite and increasing feelings of fullness. Side effects include dizziness, fatigue, and memory problems.

Qsymia (phentermine/topiramate): Qsymia, a combination of phentermine and topiramate, was approved by the FDA in 2012. It helps patients lose weight by suppressing appetite and increasing feelings of fullness. Side effects include dizziness, dry mouth, and constipation.

Belviq (lorcaserin): Belviq was approved in 2012 and worked by activating serotonin 2C receptors in the brain, reducing appetite. It was withdrawn from the US market in 2020 due to an increased risk of cancer.

Contrave (naltrexone/bupropion): Contrave, approved in 2014, is a combination of naltrexone, an opioid antagonist, and bupropion, an antidepressant. It helps patients lose weight by suppressing appetite and reducing cravings. Side effects include nausea, headache, and constipation.

Metformin: Metformin is a diabetes medication that can cause modest weight loss in some patients. It works by decreasing the absorption of glucose and reducing insulin resistance. Side effects include gastrointestinal symptoms such as diarrhea, abdominal pain, and bloating.

Ephedra and Ephedrine: Ephedra, a plant containing ephedrine alkaloids, was a popular weight loss ingredient in the 1990s and early 2000s. It was banned in the US in 2004 due to its association with serious side effects, including heart attacks, seizures, and strokes.

GLP-1 Agonists: GLP-1 agonists, such as liraglutide (Saxenda), are medications originally developed for diabetes but also approved for weight loss. They work by mimicking the effects of the hormone glucagon-like peptide-1, increasing satiety and delaying gastric emptying. Side effects include nausea, vomiting, and diarrhea. Saxenda is available by prescription in the US.