Qsymia vs. Wegovy for Weight Loss: 6 Differences to Consider

If you're looking to lose weight, there are several different medications that can help. Two common options are Qsymia (phentermine / topiramate ER) and Wegovy (semaglutide). Both medications are effective for weight loss when combined with dietary changes and regular exercise. But deciding which one is right for you can feel a bit overwhelming.

That's where GoodRx comes in. We'll compare Qsymia versus Wegovy for weight loss to help you determine which might better suit your needs. Remember, managing your health is a team effort, so be sure to discuss your options with your prescriber too.

1. Wegovy and Qsymia work differently to help you lose weight

Qsymia and Wegovy are both approved to help you manage your body weight long term. They both help reduce your appetite, but they achieve this in different ways.

Qsymia contains two medications (phentermine and topiramate) that each work differently to promote weight loss: 

• Phentermine (Adipex-P, Lomaira) is considered a stimulant medication, so it works on the brain to help reduce your appetite. Phentermine is also approved for weight loss on its own, but only as a short-term treatment. Topiramate (Topamax) is an anti-seizure medication. It isn’t exactly clear how topiramate works for weight loss. But it seems to reduce your appetite and help you feel full faster and for a longer time after eating. Topiramate isn’t FDA approved for weight loss on its own, but it’s often prescribed off-label.

Wegovy belongs to a class of medications known as glucagon-like peptide-1 (GLP-1) receptor agonists. These medications work by mimicking the effects of GLP-1, a natural hormone that regulates your appetite. Wegovy helps you feel less hungry and have fewer cravings than usual. It also slows the movement of food through your digestive tract. This can help you feel full faster when you eat, and keep you feeling full for longer afterward.

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2. Wegovy and Qsymia are administered differently

One of the most obvious differences between Wegovy and Qsymia is how you administer them.

Wegovy comes as an injectable liquid in prefilled, single-dose pens. You inject it under the skin (subcutaneously) once weekly into your stomach, upper arm, or upper thigh. The once-weekly dosage is appealing for people who have trouble remembering to take medication every day. An injectable medication like Wegovy is also helpful if you have difficulty swallowing pills. 

Qsymia doesn’t require an injection. It comes in an oral capsule that you take once a day in the morning. This may be a preferred option if you’re uncomfortable around needles or the idea of injecting yourself.

3. Qsymia may take longer to work than Wegovy

Wegovy typically starts working fairly quickly. Some people notice significant weight loss after just 4 weeks. You may start to lose weight faster after 8 to 12 weeks of starting Wegovy as your dose increases. In most cases, you’ll start with a low dose and slowly increase it over time until you reach the target maintenance dose. This can take about 4 months. But it’s best to resist the temptation to ramp your dose up faster than recommended. Doing so will just raise your risk of side effects, such as nausea and diarrhea.

It may take about 8 weeks to see significant weight loss with Qsymia. After 12 weeks, your prescriber may raise your dose if you’ve lost less than 3% of your starting body weight. Some people may need a higher dose to see significant weight loss with Qsymia. 

You can help both Wegovy and Qsymia work better by incorporating regular exercise and a reduced-calorie diet into your routine. But keep in mind that slow, steady weight loss is easier on your body and more likely to result in weight loss you can maintain. That being said, these medications don’t work for everyone. If you’re not losing weight after 12 weeks with either medication, your prescriber may decide it’s time to try a different treatment option.

4. You may lose more weight with Wegovy than with Qsymia

Wegovy and Qsymia haven’t been directly compared in clinical studies, so we don’t know for sure if Qsymia works better than Wegovy or vice versa. So we can only look at how effective they were in their own studies to get an idea of which medication may work better for weight loss.

In the largest Wegovy study, the average weight loss for people receiving Wegovy was about 15% of their starting body weight after 68 weeks (almost 16 months). More than 86% of participants lost 5% or more of their starting body weight. Around 69% of participants lost at least 10% of their starting weight. And more than 50% experienced a body weight reduction of 15% or more.

In Qsymia studies, the average weight loss for people taking Qsymia was around 8% to 10% after 56 weeks (about 13 months). About 70% of participants lost at least 5% of their initial body weight after taking the highest Qsymia dose for 1 year. And almost 50% lost at least 10% of their starting weight.

Based on these results, Wegovy seems to result in more weight loss overall than Qsymia. But both medications are considered very effective weight-loss options.

5. Wegovy may be a better choice if you have heart disease

Wegovy not only helps you lose weight, it can improve your heart health, too. A clinical study found that Wegovy can lower the risk of serious cardiovascular events (heart attack, stroke, or cardiovascular death) in certain people with heart disease by 20%. It has also been shown to benefit certain people with heart failure.

One study found that Qsymia reduced blood pressure better than phentermine alone or a placebo (pill with no medication in it). But we don’t know whether it lowers the risk of cardiovascular events. So if you’re living with or at high risk for heart disease, Wegovy may be a better choice to help you lose weight.

6. Qsymia and Wegovy have different interactions to consider

Possible drug interactions may be a factor in deciding if Qsymia or Wegovy is a better option for you.

Although it’s not a complete list, the following types of medications can interact with Wegovy:

• Certain diabetes medications: Insulin, sulfonylureas, and meglitinides (“glinides”) are more likely to cause low blood glucose (sugar) levels if they’re combined with Wegovy.

• Oral medications: Wegovy slows down how fast your stomach empties into the intestines. This could affect the absorption of oral medications you take, including oral birth control pills.

Qsymia has more drug interactions to consider, including:

• Monoamine oxidase inhibitor medications (MAOIs), such as phenelzine (Nardil)

• Alcohol

• Sedating medications, such as benzodiazepines and antihistamines

• Amitriptyline

• Some anti-seizure medications, such as phenytoin (Dilantin)

• Some diuretics (“water pills”), such as hydrochlorothiazide

If you take a medication that significantly interacts with Qsymia or Wegovy, a different weight-loss medication may be a safer option for you. Make sure your prescriber has your updated medication list to review. This can help them identify any possible issues before they occur.

7. Wegovy and Qsymia have different risks and side effects

Wegovy and Qsymia also have different safety profiles to consider.

Qsymia contains phentermine, which is a controlled substance. This means it carries a risk of dependence and misuse. And it may not be the best choice if you have a history of substance use disorder. Other Qsymia side effects include tingling sensations, dizziness, and taste changes. Some people experience mood changes, too.

Qsymia is known to cause birth defects. So if you’re able to get pregnant, the FDA requires you to have monthly pregnancy tests and use proper birth control while you’re taking it.

Common Wegovy side effects are mainly stomach-related, such as nausea, vomiting, and diarrhea or constipation. Other side effects include headache, gas, and fatigue.

Wegovy has been linked to potential long-term risks, including gallbladder problems, an inflamed pancreas (pancreatitis), and blocked intestines (bowel obstruction). It also has a boxed warning (the FDA’s most serious medication warning) for the risk of thyroid C-cell tumors. So it’s not recommended if you have a personal or family history of medullary thyroid carcinoma, or if you have Multiple Endocrine Neoplasia syndrome type 2.

As with drug interactions, it’s best to discuss the risks of Wegovy and Qsymia with your healthcare team. They can review your personal medical history and help you weigh the risks and benefits of each option.

There are ways to save on Wegovy and Qsymia

Wegovy and Qsymia are available as brand-name medications. GoodRx can help you navigate ways to save on your prescription.

• Save with GoodRx. GoodRx can help you save over 20% off the average retail price of Wegovy. Wegovy’s price at certain pharmacies is as low as $1323.00 with a free GoodRx discount. You can also use GoodRx to purchase a 30-day supply of Qsymia at an exclusive cash price of $149.10.

• Save with a copay savings card. If you have commercial insurance and meet eligibility requirements, Wegovy’s price is as little as $0 per month with a manufacturer’s savings card. If your insurance doesn’t cover Wegovy, additional discounts are available. Qsymia’s price is as low as $70 per month with a copay card from the manufacturer.

• Save with home delivery. NovoCare Pharmacy can deliver Wegovy to cash-paying patients for $499 per month. A similar program, called Qsymia Engage, can deliver a 30-day supply of Qsymia for as low as $98 per month.

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Written by:

Patricia Weiser, PharmD

Patricia has 16 years of pharmacist experience. She previously held positions as a community pharmacist, pharmacy manager, and hospital pharmacist.

Edited by:

Stacia Woodcock, PharmD

Stacia Woodcock, PharmD, is a pharmacy editor for GoodRx. She earned her Doctor of Pharmacy degree from the University of Kentucky and is licensed in New York and Massachusetts.

Reviewed by:

Alyssa Billingsley, PharmD

Alyssa Billingsley, PharmD, is the director of pharmacy content for GoodRx. She has over a decade of experience as a pharmacist and has worked in clinical, academic, and administrative roles.

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