The FDA has already approved more than a dozen weight-loss medications, and researchers are running just as many new formulations through early trials. Out of these medications, GLP-1s are gaining popularity fast. Gallup reports that 91% of Americans have heard about these weight-loss drugs, and 11% are currently taking them. But that doesn’t mean GLP-1s are the only choice. 

Another medication, Qsymia®, uses an entirely different mechanism than GLP-1s. But both treatments are effective. The right choice depends on your personal goals and health history. 

This guide explains the difference between GLP-1s and Qsymia® so you can make more informed and confident decisions about your weight loss journey.

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GLP-1s vs. Qsymia®: Key differences at a glance

GLP-1 medications activate the receptors of GLP-1, a hormone your gut releases after you eat. These receptors tell your brain to feel full, slow stomach processing, and adjust insulin and glucagon levels to regulate blood sugar. 

Researchers first created GLP-1s to extend the effects of the natural hormone, initially for glycemic control in type 2 diabetes patients. But in clinical trials, patients on GLP-1s shed high percentages of their weight, prompting researchers to study these drugs for weight management purposes. Today, four formulations are FDA-approved for weight loss: semaglutide (Wegovy®), tirzepatide (Zepbound®), liraglutide (Saxenda®), and orforglipron (Foundayo®).

Qsymia® isn’t a GLP-1 treatment. Instead, it pairs two active ingredients: 

• Phentermine has been used for appetite suppression since 1959. It triggers norepinephrine, a natural chemical that puts eating on the back burner as part of your body’s fight-or-flight response. 
• Topiramate was first introduced for seizures in 1996. The drug caught researchers' attention when patients taking it for epilepsy kept losing weight. The reason it leads to weight loss is less understood. We know it enhances GABA, a calming chemical, and lowers glutamate, an activating one. Researchers believe that this reduces the drive to eat. Additionally, topiramate alters the taste of food, making it less appetizing.

In 2012, the FDA approved the combination of the two under the brand name Qsymia®. 

Qsymia® and GLP-1s support weight loss through very different paths. Here’s a quick look at how the two compare:

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GLP-1s vs. Qsymia®: What should you know about side effects and risks?

Because they work through distinct mechanisms, side effects for Qsymia® and GLP-1s look very different.

Qsymia® side effects

Qsymia®’s most common side effects during clinical trials were tingling in the hands, feet, or face (20%), dry mouth (19%), and constipation (16%). Qsymia® also raised resting heart rate by about 3.6 beats per minute compared to placebo.

Less common but serious risks you should know about include:

• Birth defects: In clinical trials, topiramate raised the rate of oral clefts to 1.4%, about 12 times the baseline. Because of this, the FDA requires Qsymia®'s manufacturers to create a Risk Evaluation and Mitigation Strategy. Patients need to get the medication through certified pharmacies and take monthly pregnancy tests.
• Suicidal thoughts: Antiepileptic drugs like topiramate nearly double the chance of suicidal thoughts. Providers should monitor mood closely during treatment. 
• Cognitive effects: The share of patients with difficulty concentrating or finding words rose to 7.6%, compared to 1.5% in the placebo group.
• Dependence and withdrawal: Patients getting off Qsymia® need to taper the drug gradually to decrease the risk of seizures.

Side effects of GLP-1s

The most common GLP-1 medicine side effects are gastrointestinal (GI). For example, in clinical trials, patients taking Wegovy® reported nausea (44%), diarrhea (30%), and vomiting (24%). These reactions tend to be strongest when you start treatment and escalate dosage. Often, they improve as your body adjusts. 

All four GLP-1s approved for weight loss share some less common but serious risks:

• Thyroid C-cell tumors: These drugs caused thyroid tumors in rodents during trials. We still don’t know if this finding extends to humans, but GLP-1s are off-limits for anyone with a personal or family history of medullary thyroid carcinoma or MEN 2, a rare genetic condition.
• Pancreatitis: This is a rare but sometimes fatal inflammation of the pancreas. Stop treatment and contact your provider if you suddenly feel severe stomach pain that may spread to your back.
• Gallbladder disease: Significant weight loss for any reason makes the liver release additional bile that can crystallize as gallstones. These gallstones can irritate or even get stuck in the biliary tracts, causing pain or inflammation.
• Acute kidney injury: Prolonged nausea, vomiting, or diarrhea can lead to dehydration, which can affect kidney function.

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GLP-1s vs. Qsymia®: How much weight can you lose?

The CONQUER trial reviewed Qsymia®’s effectiveness in adults taking the medication for over 56 weeks. Results showed that, like most drugs, Qsymia® dosage affects treatment outcomes:

Here’s how GLP-1s compare in clinical trials:

Before covering either medication, most employer-sponsored plans require prior authorization. That means your provider submits documentation of your medical history and diagnosis, and your insurer decides whether to approve the prescription. This process can take days or even weeks. Some plans also require you to try a lower-cost option before your insurer will cover a more expensive one.

Maven Clinic’s GLP-1 Care Program connects you with specialists who can help you navigate these access barriers, identifying which medications your plan covers and adjusting your treatment plan without charging separate appointment fees for every change.

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How to choose between GLP-1s and Qsymia®

There’s no clear “best” weight loss medication. Your provider will recommend the best fit based on your history, goals, and what you can sustain long-term.

Qsymia® may be a better fit if:

• Cost is a primary concern.
• You also experience migraines. Topiramate holds independent FDA approval for migraine prevention, so Qsymia® may address both conditions with a single prescription. 
• A weight loss target of 7–11% meets your goals. 
• Your insurer requires step therapy before covering GLP-1s.
• You’re comfortable with daily dosing.

A GLP-1 may be a better fit if: 

• You’re aiming for more significant weight loss.
• You have established cardiovascular disease. Wegovy® has an FDA-approved indication for reducing the risk of heart attack, stroke, and cardiovascular death.
• You have a history of mood disorders or concerns about cognitive side effects.
• You prefer a weekly schedule.

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Finding the right weight loss plan with Maven Clinic

GLP-1s and Qsymia® have different mechanisms, risks, and price points. Choosing between one of them is a personal decision. 

Maven Clinic’s GLP-1 Care connects you with specialists who can help you evaluate your options and build an evidence-based treatment plan tailored to your hormonal and metabolic health. Learn more and start your journey with Maven Clinic.