Ask a Pharmacist: What is the Strongest Weight Loss Prescription Pill?

Key Takeaways

The new FDA-approved weight loss drug Zepbound (tirzepatide) may be the strongest weight loss drug available. Zepbound is a once-weekly injectable medicine.
Qsymia may be a stronger weight loss pill than phentermine since Qsymia contains both phentermine & topiramate, which both cause decreased appetite.
Other FDA-approved weight loss drugs include Xenical (orlistat), Contrave (bupropion/naltrexone), Saxenda (liraglutide), Wegovy (semaglutide), and Imcivree (setmelanotide).

A healthy diet and exercise program is the best way to lose weight. But if lifestyle interventions are not enough, adding prescription weight loss medications may help. Some anti-obesity medications work as an appetite suppressant, while others reduce fat absorption from food.

The U.S. Food and Drug Administration (FDA) has approved several chronic weight management medications in recent years. To find out which weight loss prescription pills are the strongest, the BuzzRx team asked HaVy Ngo-Hamilton, PharmD, to weigh in on this hot topic.

Please continue reading to find out which weight loss medication is associated with the most weight loss, based on input from our BuzzRx pharmacist.

What is the strongest weight loss pill available?

“The new weight loss drug Zepbound may be the strongest weight loss drug available. This obesity medicine is FDA-approved for chronic weight management to be used in combination with diet and exercise,” Ngo-Hamilton explains.

Zepbound is not a pill but rather a once-weekly subcutaneous (under the skin) injection. Tirzepatide, the active ingredient in Zepbound, was already approved under the brand name Mounjaro to achieve better glycemic control in adults with type-2 diabetes. It is similar to semaglutide, the active ingredient of Ozempic and Wegovy. Ozempic is approved to treat diabetes, and Wegovy is used for weight management.

“The FDA completed a safety review of Zepbound in November 2023. It has shown great results in helping adults with obesity to lose weight. However, like any other medications, people react differently to the same drug, and one weight loss drug might work better for you than others,” Ngo-Hamilton explains. “Be sure to discuss the potential adverse effects with your doctor before starting this or any other medication.”

What is the success rate of tirzepatide (Zepbound) for weight loss?

Clinical trials have shown the following in regards to the success rates of tirzepatide (Zepbound):

A large clinical trial enrolled adults without diabetes with an average starting body weight of 231 pounds and an average BMI of 38 kg/m². People who were randomized to receive Zepbound 15 mg once a week lost 18% of their body weight on average.

Another clinical trial enrolled adults with type-2 diabetes with an average starting total body weight of 222 pounds and an average BMI of 36 kg/m². People who received Zepbound 15 mg once a week lost 12% of their body weight on average.

Learn more about tirzepatide being approved for weight loss.

What are the long-term effects of tirzepatide (Zepbound)?

The manufacturer of tirzepatide (Zepbound), Eli Lilly, conducted the SURMOUNT-4 trial to investigate the effects of continued treatment with tirzepatide at maximum tolerated doses compared with placebo. This trial includes 2 periods: a 36-week open-label period during which all participants received tirzepatide, followed by a 52-week double-blind treatment period. Participants were randomized to either continue on tirzepatide or switch to a placebo.

“The results showed that the people who continued taking Zepbound (tirzepatide) for an additional 52 weeks achieved an additional 6.7% weight loss. Thus, participants who received tirzepatide during the 2 trial periods achieved a total average weight loss of 26.0% after 88 weeks,” explains Ngo-Hamilton.

In contrast, people who were switched to placebo following the initial 36-week period experienced weight gain, with an average of 14.8% weight regained at 88 weeks.

What weight loss pill is stronger than phentermine?

“A weight loss pill such as Qsymia may be stronger than phentermine,” explains Ngo-Hamilton. Qsymia contains a combination of phentermine, appetite suppressant and & topiramate, an anticonvulsant. Phentermine belongs to a group of drugs called appetite suppressants. Topiramate belongs to a group of drugs called anticonvulsants.

“Both medicines cause decreased appetite and may be stronger than phentermine alone.”

Check out our blog to find out if phentermine is a safe weight loss treatment.

Other weight loss drugs, such as GLP-1 receptor agonists such as liraglutide (Saxenda) and semaglutide (Wegovy), may also work better for some people. Learn more about Wegovy’s uses and side effects.

What prescription drugs make you lose weight fast?

According to the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), over 42% of Americans are obese. Excess weight increases the risk of serious weight-related health conditions, including high blood pressure, high cholesterol, heart disease, diabetes, liver disease, and certain cancers.

When a healthy diet and exercise are not enough, Ngo-Hamilton says that the following prescription weight-loss medications may be used to treat overweight and obese adults:

Orlistat (Xenical): This is a lipase inhibitor that prevents some of the fat in food from being absorbed by the body.
Phentermine (Adipex-P, Lomaira): This drug works to suppress appetite through its effects on the part of the brain that regulates appetite. Learn about phentermine side effects.
Phentermine-topiramate (Qsymia): This is a combination of an anorectic or appetite suppressant (phentermine) and an anticonvulsant (topiramate). The combination is used for treating obesity because it reduces appetite and makes you feel full sooner.
Naltrexone-bupropion (Contrave): This is a combination of an opiate antagonist (naltrexone) used to treat alcohol and opioid drug abuse and an antidepressant (bupropion) used to treat depression and help with smoking cessation. They are used in obesity treatment because they reduce hunger and food cravings.
Liraglutide (Saxenda): This is a glucagon-like-peptide 1 (GLP-1) receptor agonist. It helps to regulate appetite and food intake.
Semaglutide (Wegovy): This is a GLP-1 receptor agonist. It delays gastric emptying, increases feelings of fullness, and reduces appetite. Compare Wegovy vs phentermine for weight loss.
Tirzepatide (Zepbound): This is a dual glucagon-dependent insulinotropic polypeptide (GIP) receptor and GLP-1 receptor agonist that slows gastric emptying, increases fullness, and reduces appetite and caloric intake.
Setmelanotide (Imcivree): This is a melanocortin 4 (MC4) receptor agonist that increases fullness, decreases appetite, and increases the resting metabolic rate.

What is the only OTC FDA-approved weight loss pill?

“The only FDA-approved weight loss pill that is available without a prescription is orlistat 60 mg (Alli). The 120-mg dose of the same drug, orlistat, is sold under the brand name Xenical and is only available with a doctor’s prescription,” says Ngo-Hamilton.

In addition to over-the-counter products, the prescription medications listed above are FDA-approved weight loss pills or injections that promote weight loss when used along with a low-calorie diet and exercise program.

What body mass index qualifies for a weight loss drug?

Prescription weight loss drugs are used to treat obesity in people who have:

A body mass index (BMI) of 30 kg/m² or higher.
A BMI of 27 kg/m² or higher and at least one of the weight-related medical problems such as high blood pressure, high cholesterol, or diabetes.

“While an obesity medicine specialist may recommend prescription drugs for chronic weight management, remember that these drugs are not a substitute for diet and exercise,” Ngo-Hamilton says. “Prescription weight loss medications work best when used with a reduced-calorie diet and increased physical activity.”

How much body weight do you lose on weight-loss drugs?

“Losing weight reduces many health risks and can boost self-esteem, thus improving a person's quality of life and social interactions. However, regardless of which weight loss drug is being used, they are not the "magic pill" that results in overnight weight loss,” says HaVy Ngo-Hamilton, PharmD.

Taking weight loss pills or injections for a year can result in a reduction in body weight by 3-12% more than what could be achievable with lifestyle changes like diet and exercise alone.

“This means a person who weighs 200 lbs (pounds) can expect to lose 6 lbs to 24 lbs after a year on weight loss drugs in combination with a low-fat diet and exercise,” explains HaVy.

“Although this may not seem like a lot,” she continues. “It’s worth noting that losing just 5-10% of your body weight and keeping it off can lower your risk of many serious health problems, including high blood pressure, high blood sugar, and high cholesterol.”

How much weight can you lose on the strongest weight-loss drug?

Zepbound (tirzepatide) is a once-weekly injectable medicine. It is a dual GIP and GLP-1 receptor agonist. Individual results may vary, but clinical trials have shown an average weight loss of 25% in:

15.3% of adults taking 5 mg
32.3% of adults taking 10 mg
36.2% of adults taking 15 mg (the maximum dose)

Do you regain lost weight when you stop taking weight loss medications?

“It is quite common to regain some of the lost weight after you stop taking weight loss drugs. Eating a healthy diet and getting regular exercise can help with weight management in the long term,” Ngo-Hamilton says.

Are weight loss drugs covered by insurance?

“Anti-obesity drugs that have received FDA approval are likely to have insurance coverage,” Ngo-Hamilton says. Many of these weight loss medications may require prior authorization by the insurance company. However, you should check your specific health insurance plan for details.

Ngo-Hamilton continues to say, “Your doctor may also have insights on this topic. A free BuzzRx discount coupon may help you save on weight loss drugs.”

What are the risks of taking anti-obesity medications?

Weight loss medications can help in losing weight and may even result in dramatic weight loss. But they carry some serious risks.

Common side effects include abdominal pain, nausea, vomiting, diarrhea, and constipation.

Weight loss drugs have also been linked to serious risks such as an increased risk of thyroid cancer, severe liver injury, pancreatitis, kidney disease, gallbladder disease, birth defects, and other health complications.

Besides health complications, rapid weight loss is often associated with wrinkles and skin sagging.

“As the skin loses elasticity, the change in appearance is more prominent in the face,” says Ngo-Hamilton. “The term “Ozempic face” describes facial symptoms experienced by people taking Ozempic, which include increased signs of aging with more lines and wrinkles on the face.”

Ozempic face is described as a hollowed-out appearance of the face.

“Talk with your doctor and pharmacist about the risks versus benefits of taking weight loss medications. Keep track of U.S. Food and Drug Administration (FDA) drug safety communication for any recalls,” Ngo-Hamilton advises.

Before starting a weight loss drug, give your healthcare provider a complete list of your other medications, including prescription drugs, over-the-counter products, dietary supplements, and herbal products. This will help avoid potentially dangerous drug interactions with other medications.

Also, give your provider a detailed medical history because prescription weight-loss drugs may not be safe for everyone.

Why is there a shortage of Wegovy?

HaVy called out the shortage of Wegovy and Ozempic since 2022 due to a drastic increase in demand, cautioning consumers about the dangers of fake products being sold on the market.

“Wegovy and Ozempic continue to make headlines, creating opportunities for selling fake products,” says Ngo-Hamilton. “Fake Ozempic has been found in the U.S. and Europe, containing insulin instead of semaglutide, leading to dangerous complications requiring hospitalization.”

As mentioned, while both medications contain semaglutide, only Wegovy is an FDA-approved weight loss medication. Ozempic is only approved to treat adults with type-2 diabetes.

Ngo-Hamilton also aims to bring awareness to accessibility issues with these medications. “Diabetic patients who would be benefiting from Ozempic therapy now aren't able to start or continue on Ozempic because it is in such high demand as a weight loss medication,” she explains.

In summary

In summary, Ngo-Hamilton states, “If lifestyle interventions alone aren't enough to achieve meaningful weight loss, you should talk to your doctor about the risks and benefits of pharmacological interventions with one of the weight loss medications. Your doctor can help determine if weight loss medication is safe and potentially beneficial.”

If you are already on Wegovy or Ozempic for whatever reason and you have problems accessing the medicines, you should work with your doctor for the best course of action with the ongoing shortage.

Ngo-Hamilton encourages everyone to take caution when trying to access these medications. Be mindful of the risks, and always talk to your doctor before starting any new drugs. “Although Ozempic and Wegovy contain semaglutide, these products are not interchangeable. Purchasing Ozempic or Wegovy from illegitimate sources can cause serious health complications, not to mention a lot of these criminal organizations can steal your money with non-delivery schemes, meaning they will never deliver the drug product after payment is received,” Ngo-Hamilton advises.

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