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FDA-Approved Weight Loss Drugs: Can They Help You?

Medically reviewed by Leigh Ann Anderson, PharmD. Last updated on June 17, 2021.

The Skinny on Weight Loss: Is There a Magic Pill?

No matter how many times we wave our wand, the quest for a magic weight loss pill has been elusive to date.

While many pills claim to lead to weight loss, in reality, it is the hard work of diet and exercise that ultimately leads to healthy and sustainable weight loss. However, when weight loss medications are combined with diet and exercise, as they should be, an added benefit may be seen.

Weight loss agents are available on the U.S. market that can help patients lose roughly 3% to 9% of their weight when combined with diet and exercise. Be sure to talk to your doctor for sound advice before starting any weight loss program, and understand it will take time and discipline.

The Obesity Crisis: A National Epidemic

According to the U.S. Centers for Disease Control and Prevention (CDC), there has been a dramatic increase in obesity in the last 20 years. Based on the most recent numbers, the prevalence of obesity is over 40% and affects roughly 93 million U.S. adults. The prevalence of severe obesity is 9.2% of the population.

These numbers are especially astounding because obesity and obesity-related conditions account for some of the leading causes of preventable deaths in the U.S.

Obesity-related conditions include:

In addition, being overweight or obese is a recognized risk factor for many other major health problems including osteoarthritis, sleep apnea and other breathing problems, mental health issues like depression, and gallbladder disease.

What is Your BMI?

Most weight-loss medications are prescribed based on your body mass index (BMI). It's important to understand how this is calculated so you can discuss it with your provider.

  • BMI is a calculation of your weight in relation to your height that defines your health risk.
  • Obesity is defined as a BMI over 30 kilograms/meter squared (kg/m2).
  • A BMI of 25 to 30 is considered overweight. A BMI of 18.5 to 24.9 is considered healthy.

In general, you should not use weight loss medications unless you are at risk for a health-related condition, such as type 2 diabetes or high blood pressure. A low-fat diet and regular exercise are part of the weight-loss regimen that should be continued even if weight loss medicines are stopped.

Qsymia and Belviq

In 2012, Qsymia and Belviq were the first weight loss drugs approved in over a decade. Belviq (lorcaserin) was withdrawn from the market in 2020.

Qsymia (phentermine and topiramate) is from Vivus Pharmaceuticals.

  • In 56-week long clinical trials, patients lost on average 32 lbs. using Qsymia 15/92 mg plus diet and exercise, and about 5 inches off of their waist.
  • Patients using a placebo (an inactive treatment) lost 6 lbs and 1.7 inches.
  • Qsymia is a C-IV controlled substances approved for use in adults.

In 2020, the FDA requested the withdrawal of Belviq and Belviq XR (lorcaserin) from the US market due to an increased risk of cancer.

  • Based on studies involving 12,000 people tracked for more than five years, the data showed that 7.1% of those taking a "dummy" placebo developed cancer, but that number rose to 7.7% among those taking Belviq.
  • Cancer types included: pancreatic, colorectal and lung cancer.

How Does Qsymia Work?

Qsymia is a combination of two drugs, phentermine and extended-released topiramate. Phentermine acts to suppress the appetite, and topiramate (normally used as an anti-seizure medicine), is used because it may help people feel full.

Qsymia is used for weight control in two groups:

  • Those who are obese (BMI of 30 kg/m2 or higher)
  • Those who are overweight (BMI of at least 27 kg/m2) and also have at least one weight-related condition, such as type 2 diabetes, high blood pressure, or high cholesterol.

Dosing: The Qsymia dose is taken once daily in morning; patients should avoid an evening dose as it may keep them awake. The manufacturer provides a BMI dosing chart using patient height and weight in the product label. Your doctor will slowly increase your dose over a 28-day period.

Your doctor will evaluate your weight loss after 12 weeks of treatment with Qsymia.

Important Facts About Qsymia

Qsymia may cause birth defects, so do not use Qsymia if you are pregnant or planning a pregnancy.

Women will need a negative pregnancy test before starting Qsymia and each month while on therapy. Use an effective birth control to prevent pregnancy; discuss your birth control options with your health care provider before starting Qsymia. If you become pregnant while on treatment, call your healthcare provider immediately.

Do not use Qsymia if you have glaucoma, thyroid disease or use monoamine oxidase inhibitor drugs.

  • You can check for Qsymia drug interactions here.
  • Be sure to ask your pharmacist about possible drug interactions with prescription, vitamin, or herbal or dietary supplements.

If you have not lost a certain percent of your weight after 12 weeks (3% to 5%), your doctor may decide to stop Qsymia treatment or change your dose. Do not stop treatment on your own too quickly as it may cause seizures; always talk to your doctor first.

What Are the Most Common Side Effects with Qsymia?

Common side effects with Qsymia may include

  • numbness or a tingling sensation
  • dizziness
  • unusual taste
  • difficulty sleeping
  • constipation
  • dry mouth
Mood problems, difficult concentration, and low blood sugar may also occur.

Due to the possibility of drug interactions when you take Qsymia with other prescription, over-the-counter or herbal weight loss medications, talk to your doctor or pharmacist before you combine any medications.

Contrave and Saxenda

Contrave (bupropion and naltrexone) is an extended-release form of two previously approved drugs, naltrexone and bupropion, and was approved in September 2014.

  • Bupropion is an antidepressant medicine that can also lower your appetite. Naltrexone is used to block the effects of narcotics or alcohol in addiction but may also curb hunger and food cravings.
  • In three, 56-week long clinical trials, patients who added Contrave to diet and exercise lost about 2 to 4 times more weight than with diet and exercise alone. In one study, patients in an intensive diet and exercise program and one-year of Contrave treatment lost 25 lbs. on average.

Saxenda (liraglutide), from Novo Nordisk is a glucagon-like peptide-1 (GLP-1) analogue for the treatment of obesity and was FDA-approved in 2014 for weight-loss due to obesity.

  • It is given as a subcutaneous (under the skin) injection once a day and is used in addition to diet and exercise.
  • In a Saxenda study with over 3,700 patients, roughly 33% of people using Saxenda had a weight loss of 10% or more, losing about 23 lb from when they started the study. Approximately 6% of patients lost an average 47 lb.

Contrave: A Combo Drug

Contrave is an extended-release tablet of two previously approved drugs, naltrexone and bupropion.

  • When used alone, naltrexone, an opioid antagonist, is approved to treat alcohol or opioid dependence.
  • Bupropion is an aminoketone antidepressant used for major depressive disorder, seasonal affective disorder and as an aid to quit smoking.
  • When used together, these medications act on two areas of the brain to help with weight loss. Contrave is not approved to treat depression or other psychiatric conditions, or to help you quit smoking.

Contrave is used in obese or overweight adults with at least one weight-related condition such as high blood pressure, high cholesterol, or type 2 diabetes. It's used with diet and exercise.

  • Contrave comes as extended-release tablets (8 mg naltrexone with 90 mg bupropion). The dose is increased weekly for 4 weeks, until a total daily dosage of two Contrave 8 mg/90 mg tablets given twice a day is reached.
  • Total daily doses greater than 32 mg/360 mg (2 tablets twice a day) are not recommended. Do not take Contrave with a high fat meal.
  • Safety and side effect concerns include behavioral changes, suicidal thoughts, seizure risk, elevated blood pressure, and added effects with alcohol, among others. Do not drink alcohol with Contrave.
  • Contrave labeling contains a Boxed Warning, the FDA's most strigent safety warning, for increased risk of suicidal thoughts and behaviors.

Saxenda (liraglutide)

Saxenda (liraglutide), from Novo Nordisk, is an injection for chronic weight management.

  • As with the other prescription weight loss products, Saxenda is used in addition to diet and exercise for obese or overweight patients based on their BMI with at least one weight-related condition such as hypertension, type 2 diabetes, or high cholesterol.
  • Liraglutide is also approved at a lower dose for use in type 2 diabetes (brand name Victoza), but the two drugs should not be used together or with any other glucagon-like peptide-1 (GLP-1) receptor agonist (also called incretin mimetics).

Saxenda comes in a prefilled pen. The suggested dose of Saxenda is a 3 mg subcutaneous (under the skin) injection once a day. It is given in the stomach area, thigh or upper arm.

  • Follow the recommended dose escalation schedule to reduce the likelihood of stomach side effects like nausea.
  • If a patient cannot tolerate the 3 mg dose, Saxenda should be discontinued, as effectiveness has not been shown at lower doses.

Alli: A Lower-Dose, OTC Version of Prescription Xenical

Alli (orlistat):

  • is the over-the-counter (OTC) version of the FDA-approved prescription drug Xenical but it comes in a lower 60 milligram (mg) strength.
  • is used in adults in conjunction with diet and regular exercise to promote weight loss.

Alli decreases the absorption of dietary fat by about 25% and therefore reduces the number of calories absorbed.

Clinical trials have only shown it to be only modestly effective; in general, a weight loss of 3 to 5 lb per year would be expected over and above what you might lose from dieting and exercise alone.

Alli: Use and Side Effects

  • Alli (orlistat) is taken as one 60 mg capsule three times a day with each meal containing fat, but don't exceed more than 15 grams of fat per meal.
  • You should expect to lose most of your weight in the first 6 months.
  • Use Alli in combination with diet and exercise.
  • Do not take more than 3 capsules per day.

It is also recommended to take a daily multivitamin at bedtime to help offset the loss of any fat-soluble vitamins. The vitamin should contain the fat soluble vitamins A, D, E, K & beta carotene. Those with diabetes, thyroid disease or taking a blood thinner should consult with their doctor before using Alli.

Side effects with Alli often hinder its use: loose stools, oily spotting, gas, bowel incontinence, and rarely liver injury (jaundice) may occur.

Symptoms of liver injury include:

  • yellow skin or eyes
  • itching
  • brown urine
  • stomach pain.

Wegovy (semaglutide)

Wegovy (semaglutide) is a glucagon-like peptide-1 (GLP-1) receptor agonist to be used in addition to diet and exercise for long-term weight management in adults who are obese (BMI ≥30 kg/m2) or overweight (BMI ≥27 kg/m2) with at least one weight-related medical problem like high blood pressure, high cholesterol or type 2 diabetes.

  • It was first approved in June 2021 and is manufactured by Novo Nordisk. Wegovy contains semaglutide and should not be used with other semaglutide-containing products or other GLP-1 receptor agonist medicines.
  • A big advantage of Wegovy is that it is given as a once-weekly subcutaneous (under the skin) injection. It is injected on the same day each week, at any time of day, with or without meals.
  • It comes in a self-administered pre-filled, single-dose pen for injection.

In clinical studies, patients taking Wegovy achieved an average weight loss of 14.9% of body weight at 68-weeks vs. 2.4% for placebo. In addition, 83.5% of patients achieved 5% or more body weight reduction in the Wegovy group compared to 31.1% for those taking a placebo (an inactive treatment).

The most common side effects with Wegovy include nausea, diarrhea, vomiting, constipation, stomach pain, headache, fatigue, dyspepsia, dizziness, stomach distension, eructation (belching), low blood sugar in patients with type 2 diabetes, flatulence (gas), gastroenteritis, and gastroesophageal reflux disease (GERD).

Comparative Effectiveness of Weight Loss Drugs

Of course, the big question is "Which weight loss medication is the best?"

Each weight loss treatment should be individualized based on the patient, but a study published in the Journal of the American Medical Association (JAMA) looked at this question.

  • In the study, researchers analyzed findings from 28 clinical trials with over 29,000 participants.
  • Five approved drugs for obesity were evaluated: Qsymia, Saxenda and Xenical, along with Belviq (now discontinued) and Contrave.
  • All agents were associated with significant weight loss of at least 5 % compared with a placebo (an inactive sugar pill) at one year. Phentermine-topiramate (Qsymia) and liraglutide (Saxenda) were associated with the highest odds of achieving at least 5% weight loss.
  • In some cases a significant number of people dropped out because of side effects.

Qsymia (phentermine and topiramate XR): Typically, people lost the most weight with Qsymia, roughly 19 pounds more than those taking a placebo. Study patients were 9 times more likely to drop at least 5% of their initial weight.

Xenical (orlistat) or (discontinued) Belviq (lorcaserin): People in these groups tended to lose 6 to 7 pounds more than placebo users over one year, the least amount of weight loss of all drugs studied. Belviq is no longer available in the US due to a possible cancer risk.

Contrave (bupropion and naltrexone) and Saxenda (liraglutide): Patients typically lost 11 to 12 pounds more in this group, compared with placebo, over one year. But, compared to placebo, Saxenda and Contrave were linked with the highest odds of stopping treatment due to side effects.

Stimulant Weight Loss Drugs

Drugs that are considered stimulant weight loss drugs include:

These stimulants are controlled substances approved for short-term use in weight loss, usually only up to 12 weeks. These drugs can lead to abuse and dependence with long-term use. As with other weight loss treatments, these drugs should be used in conjunction with ongoing diet and exercise to maintain weight loss.

Often, the weight that is lost with stimulants will be regained when the medication is stopped. In contrast, Alli, Contrave, Qsymia and Wegovy are all approved for long-term (chronic) use to maintain weight loss.

Are OTC Herbal Weight Loss Pills Safe and Effective?

It is tempting to buy OTC weight loss pills -- they seem quick, easy and may claim to be "natural". However, dietary or herbal supplements are not reviewed by the FDA like prescription medicines. They may contain unknown chemicals that can be dangerous or counterfeit. Be especially careful buying these products online and only buy from a reputable website.

Chromium, Green Tea extract, Hoodia, and Guar Gum are just a few of the herbal dietary supplements available on the market today.

The FDA does investigate OTC supplements if they appear to be causing harm. In fact, the FDA removed dietary products with the stimulant ephedra from the U.S. market in 2004 due to dangerous side effects such as heart attack, stroke and seizures.

Learn More: The Dangers of Fake Drugs: Top 10 Facts on Counterfeit Meds

Finished: FDA-Approved Weight Loss Drugs: Can They Help You?

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  • FDA Approves New Drug Treatment for Chronic Weight Management, First Since 2014. Accessed June 17, 2021 at
  • FDA Requests Market Withdrawal of Diet Drug Belviq Due to Cancer Risk. US FDA. Accessed June 15, 2021 at
  • Khera R, Murad MH, Chandar AK, Dulai PS, Wang Z, Prokop LJ, Loomba R, Camilleri M, Singh S. Association of Pharmacological Treatments for Obesity With Weight Loss and Adverse Events. A Systematic Review and Meta-analysis. JAMA. 2016;315(22):2424–2434. Accessed June 15, 2021 at doi:10.1001/jama.2016.7602
  • Accessed June 17, 2021 at at
  • Adult Obesity Facts. Centers for Disease Control and Prevention (CDC). Accessed June 15, 2021 at
  • Saxenda [package insert]. Plainsboro, NJ: Novo Nordisk Inc. Accessed June 15, 2021 at
  • Qsymia [package insert]. Mountain View, CA: Vivus, Inc. Accessed June 15, 2021 at
  • Learn about Contrave. Accessed June 15, 2021 at
  • Benefits of Saxenda. Accessed June 15, 2021 at

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.