What Is the Strongest Weight Loss Prescription Pill?

Key takeaways

• Prescription pills that can be used for weight loss include metformin, topiramate, Qysmia^®, and orlistat.

• Qysmia may be the strongest weight loss prescription pill, but it’s not right for everyone.

• The most effective weight loss pill depends on how your body reacts to medication. It could be a custom combination of pills.

• A healthcare provider can help you find the best weight loss pill for you.

Weight loss pills can help you lose weight when lifestyle changes aren’t quite cutting it. But what is the strongest weight loss prescription pill? Unfortunately, there isn’t a simple answer to that.

The best weight loss pill for you isn’t necessarily the strongest one — it’s the one that works best for your body and has the most manageable side effects.

Below, we’ll share info on how weight loss pills work and what options you have.

When considering prescription medication — for weight loss or anything else — you want to know which option is most effective. Unfortunately, there isn’t one weight loss pill to rule them all. What works best for one person might not work for someone else, and effectiveness depends on a number of factors.

Prescription weight loss pills work in slightly different ways. They can:

• Suppress appetite

• Help you feel fuller

• Curb cravings

• Stop your body from absorbing fats from food

• Alter reward pathways to minimize binge eating

Fyi, some oral weight loss medications are approved by the Food and Drug Administration (FDA) for weight loss. Others are prescribed off-label for weight loss. This is when a medical professional prescribes a medication for a condition that isn’t on the drug label — hence the name.

Just because something is prescribed on-label doesn’t make it “stronger“ or more effective than an off-label option.

In fact, off-label prescriptions are common, and they give people more options. With an off-label weight loss medication, you might be able to access a drug that best suits your body and is more effective for you.

→ Read: How to Ask Your Doctor for Weight Loss Pills

Here’s a look at some of the strongest weight loss prescription pills. These pills are either FDA-approved for weight loss or prescribed off-label for weight loss.

1. Metformin

You might have heard of metformin as a diabetes drug. It’s also prescribed off-label for weight loss.

How does metformin work? It can lower blood sugar levels (glucose) and suppress appetite, helping you stick to nutritious food choices and portions. It can have bonus benefits, too, like reducing the risk of cardiovascular events.

Just like any medication, metformin can come with adverse effects. Common side effects of metformin include gastrointestinal side effects, like nausea. These are usually mild and subside as your body adjusts to treatment.

Research shows metformin can reduce body mass index (BMI) by about one unit. So, if your BMI is 27, taking metformin might help you lower it to 26.

2. Naltrexone

Naltrexone is FDA-approved to treat alcohol and opioid use disorders. It’s prescribed off-label as a weight loss treatment, sometimes with other ingredients.

It’s not entirely clear how naltrexone works for weight loss. It’s an opioid receptor antagonist, meaning it can block the effects of opioids in the brain. This can make substances less rewarding, which reduces cravings.

Naltrexone side effects include nausea, stomach cramps, and diarrhea.

3. Topiramate

Topiramate is sold under the brand name Topamax^®, which is FDA-approved for epilepsy and migraine attacks. Again, it’s a daily pill that can be prescribed off-label for weight loss.

Topiramate is thought to work by decreasing calorie intake and affecting metabolism. It might also alter reward pathways in the brain to reduce binge-eating behavior.

In Topamax trials, side effects included weight loss — the effect you’re probably hoping for — in addition to fatigue and a tingling sensation (paresthesia), among others.

One study found that people taking 192 or 384 milligrams (mg) a day of topiramate lost an average of about 6 percent of their starting body weight over 24 weeks.

4. Phentermine

Phentermine acts as an appetite suppressant, helping you avoid overeating.

Under brand names like Adipex-P^® and Lomaira^®, phentermine is FDA-approved for weight loss in people with obesity or overweight who have a weight-related medical condition, like:

• High cholesterol

• High blood pressure (hypertension)

• Type 2 diabetes

The big difference between phentermine and many other weight loss pills? It’s for short-term use.

Phentermine can be habit-forming, so it’s not right for everyone. A provider may prescribe it for only three to six weeks, although it’s sometimes prescribed for longer.

One study found that 15 mg of phentermine led to weight loss of about 13 pounds over 28 weeks.

5. Qsymia

Qsymia is an oral capsule that contains both phentermine and topiramate. The ingredients work together to suppress appetite and increase fullness.

Alongside diet and exercise, Qsymia is FDA-approved for weight loss in adults and children 12 or older with obesity, or adults with overweight who have a weight-related health condition.

Research found that phentermine-topiramate treatment led to more weight loss than either medication alone. Participants lost roughly 20 pounds on 15 mg of phentermine and 92 mg of topiramate taken together.

Qsymia may be one of the strongest weight loss prescription pills. But again, that doesn’t mean it’ll be the most effective for you.

6. Rybelsus^®

Rybelsus^® is an oral form of semaglutide, which is the active ingredient in the injectable weight loss medication Wegovy^® and the injectable diabetes medication Ozempic^®.

It’s FDA-approved for type 2 diabetes. But like many drugs on this list, healthcare providers sometimes prescribe Rybelsus^® off-label for weight loss in people without diabetes.

Rybelsus^® works by stimulating the pancreas to release more insulin, keeping the liver from releasing too much sugar, and slowing the rate at which food leaves the stomach.

Side effects can include nausea, vomiting, and constipation.

→ Learn more: Metformin vs. Rybelsus^®

7. Orlistat

Orlistat (Xenical^®, Alli^®) is a lipase inhibitor. That means it works by stopping the body from absorbing fats from food.

You might take orlistat tablets up to three times a day for weight loss and chronic weight management. You can get orlistat with a prescription or in a lower dose over the counter, depending on your needs.

Clinical trials on Xenial found that participants lost an average of about 13 pounds over a year.

8. Bupropion

Bupropion is an antidepressant. You might have heard of one of its brand names, Wellbutrin^®. This medication is FDA-approved to treat depression and seasonal affective disorder (SAD) and to help people stop smoking.

Healthcare providers sometimes prescribe it off-label for weight loss.

Bupropion side effects can include headache, dizziness, and dry mouth.

Hers offers access to personalized oral medication kits. Kits contain a combination of prescription weight loss pills in a formulation tailored to your goals and health history.

Compounded medications haven’t been approved by the FDA.

Your kit may include medications like:

• Bupropion

• Metformin

• Topiramate

• Naltrexone

So, what’s the strongest weight loss prescription pill for you personally? A custom combination of ingredients could be the “strongest“ or most effective weight loss pill for you.

As far as effectiveness goes, you could lose an average of 8.4 percent of your body weight in the first six months of treatment through Weight Loss by Hers.*

With a Weight Loss by Hers subscription, you’ll get access to weight loss medication, expert guidance, and the Hers app.

Through the Hers app, you’ll find:

• More than 100 high-protein recipes developed by nutritionists

• Trackers to build life-long healthy habits

• Nutrition tips tailored to your personal eating profile

• Realistic protocols to help you improve nutrition, physical activity, sleep, and stress levels

• Ongoing care and check-ins with healthcare providers — 100 percent online, at no extra cost

Oral weight loss kits start from $69 a month for a 10-month plan paid upfront in full.

*Based on self-reported data as of March 2025 from approximately 1,172 Hers customers on a personalized treatment plan, including oral medication kits, along with a reduced-calorie diet and exercise. Customers reported their weight at their initial medical consultation and check-in approximately six months later.

Real Members, Real Results From Hers Weight Loss Programs

Mary lost 38 pounds with Hers after a provider through the platform prescribed a personalized oral medication kit.

“I started my journey weighing 165 lbs … I was going through menopause, so I was gaining weight, had low energy, felt depressed, and had no motivation. I did some research … and I decided to take the survey to see which medications would be best for my symptoms. The medical provider assisted with my questions, and I ordered [the oral weight loss kit] online.

“My appetite decreased, and my water intake increased. I still got to eat the foods I loved. Today, I weigh 127 lbs. I feel great! My clothes fit better, I look better, my neighbors, family, and friends are shocked at how much weight I lost.

“I’m happier, I have more energy, I’ve lost the ’belly fat,’ and I stand by this product 100 percent … I tried so many other ’diet’ pills and ’diet’ programs and nothing worked. This was the first treatment that really worked, and I’m so happy!“

Customer’s results have not been independently verified. Individual results may vary.

To sum it all up, you have a few options when it comes to oral prescription drugs for weight loss. Here are the key details:

• What is the strongest weight loss prescription pill? The most effective prescription weight loss pill for you isn’t necessarily the “strongest“ pill. It’s the treatment that suits your health history, body, and goals.

• A healthcare provider can help. A provider will take all factors into account and recommend the treatment that’ll be the safest and most effective for you.

• It’s about more than just medication. Weight loss medication can be effective, but incorporating healthy lifestyle changes is equally as important. The Hers app offers activity trackers, healthy recipes, and personalized support to help you on your journey.

Want to explore your options for medical weight loss? Take our free online weight loss assessment. A licensed healthcare provider will go over your answers and recommend the best treatment plan for you.

That could include weight loss pills, like metformin or topiramate, or GLP-1 injections, like Zepbound^®, Mounjaro^®, and Wegovy^®.

Get answers to frequently asked questions about the strongest weight loss prescription pills below.

Are weight loss prescription pills covered by insurance?

Weight loss pills are sometimes covered by insurance, but it depends on your health, insurance plan, and which medication you go for. Insurance providers don’t tend to cover off-label use, and some don’t cover weight loss medications at all — even the FDA-approved ones.

If you can get insurance coverage, you still need to meet eligibility criteria, like having a BMI within a specific range and a weight-related health condition.

How long does it take for weight loss prescription pills to work?

How long it takes for a weight loss prescription pill to work depends on which pill you go for. In general, you may feel changes in your hunger and fullness levels within the first few days or weeks. Then you might notice weight loss within the first few weeks of treatment.

What’s the best prescription weight loss pill?

The best prescription weight loss pill depends on your health, medical history, and weight loss goals. You might find that a combination of weight loss pills suits your body best. A healthcare provider can help you determine the best weight loss pill for you.

Who is eligible for prescription weight loss pills?

In general, you may be eligible for prescription weight loss pills if you have a BMI of more than 30 or more than 27 with a weight-related health condition. A healthcare provider can make sure you don’t have any contraindications that mean you can’t take weight loss medication, like pregnancy, breastfeeding, or some medical conditions.