Qsymia for Weight Loss: How Does Qsymia Work

Learn how Qsymia helps with weight loss and understand its side effects. Take control of your weight and embrace a healthier you.

Table of Contents
  • What is Qsymia?
  • How Does Qsymia Work?
  • Who Qualifies for Qsymia?
  • Can Qsymia Be Used For Weight Loss?
  • Qsymia vs Other Prescription Weight Loss Medications
  • Qsymia Side Effects
  • Qsymia Dosage and Administration
  • Qsymia Contraindications and Warnings
  • Qsymia Coverage and Cost
  • Where Can I Get Qsymia?

Qsymia for Weight Loss

Of all the prescription weight loss medications on the market, Qsymia may have come across your radar. Scroll down to learn more about Qsymia and see if it is the right medication for you.

What is Qsymia?

Qsymia is a prescription weight loss medication that contains a combination of two drugs: phentermine and topiramate. Phentermine is an appetite suppressant, and topiramate is a commonly used anti-seizure medication. These medications are combined in different dosages for a noticeable weight loss effect. Qsymia is FDA-approved for the management of obesity.

How Does Qsymia Work?

Qsymia works by combining the effects of phentermine and topiramate. As mentioned before, phentermine acts as an appetite suppressant which helps reduce food cravings and appetite. It does this by stimulating the sympathetic nervous system, which is the same system that releases adrenaline into the blood during fight-or-flight situations. The amount of phentermine used is only enough to activate the appetite-suppressing effects of the sympathetic nervous system. Topiramate also suppresses appetite and enhances the effectiveness of phentermine. Together, these medications lead to a desired and sustainable weight loss effect.

Who Qualifies for Qsymia?

Qsymia is FDA-approved for the treatment of obesity. If you have a BMI of 30 or higher or a BMI of 27 or higher and at least one weight-related condition such as high blood pressure, diabetes, or high cholesterol, then you may be eligible to take Qsymia

Can Qsymia Be Used For Weight Loss?

Multiple large clinical trials have been published over the years showing how effective Qsymia has managed obesity. It should be noted that Qsymia should be taken along with diet and regular exercise to get the best weight loss results.

It started with the CONQUER trial published in 2011. In this study, researchers wanted to see how effectively Qsymia managed obesity. Participants were given different doses of Qsymia (7.5mg/46mg or 15mg/92mg) along with diet and exercise for 56 weeks. The results showed that participants taking Qsymia noticed an average of 8 - 10 kg (17-22 lbs) decrease in weight after 56 weeks.

This study was followed up by the SEQUEL trial. For this study, researchers enrolled participants from the original CONQUER trial and continued them on Qsymia for an additional 52 weeks to see the long-term weight loss benefits.  At the end of the study, participants noticed a sustained weight loss effect of around 9-10% of their body weight from the start of the study. It was also found that there was a reduction in rates of adverse effects after 108 weeks, showing that people could tolerate taking Qsymia over a longer period. It was also shown that Qsymia improved blood pressure and decreased the rate of diabetes compared to the placebo group.

Qsymia was also studied in patients with severe obesity (BMI > 35). In the EQUIP trial published in 2011, researchers enrolled 512 participants who were struggling with severe obesity and gave them different doses of Qsymia (3.5mg/23mg or 15mg/92mg) for 52 weeks (3). The participants also started a calorie-restricted diet while taking Qsymia for the duration of the study. After 52 weeks, participants taking Qsymia lost an average of 5-10% of their baseline body weight, with higher doses leading to a higher percent change. The researchers also noticed a significant reduction in waist circumference, blood pressure, and cholesterol levels.

Qsymia vs Other Prescription Weight Loss Medications

Qsymia vs Contrave

Contrave is an FDA-approved prescription weight loss medication that can be used for people struggling with obesity. It is a combination of two medications: Naltrexone and Bupropion.

In the COR-II trial published in 2013, researchers studied the weight loss effects of Contrave for people struggling with obesity (2). They gave the participants Contrave for 56 weeks, along with a calorie-restricted diet and regular exercise. They found that people taking Contrave lost around 6% of their body weight after 56 weeks. They also saw that Contrave reduced certain cardiometabolic risk factors, such as LDL cholesterol levels, fasting insulin levels, and waist circumference.

When comparing this to the results of the CONQUER and EQUIP trial, Qsymia seems to have a greater effect on weight loss than Contrave. However, Contrave may be a better option if you have a history of heart conditions, specifically arrhythmias. Since Contrave contains the antidepressant bupropion, there may be a potential benefit for those suffering from depression.

Qsymia vs GLP-1 medications

The GLP-1 agonist medications are a group of medications that are used to treat type 2 diabetes and obesity. They are mostly once-weekly to once-daily pen injections, except of  Rybelsus, which is an oral form of the GLP-1 agonists. Some examples are:

  • Mounjaro (Tirzepatide)
  • Wegovy, Ozempic, and Rybelsus (Semaglutide)
  • Trulicity (Dulaglutide)
  • Victoza and Saxenda (Liraglutide)

They work by mimicking the naturally produced hormone GLP-1, which regulates blood sugar, decreases appetite, and reduces food cravings. These medications have been shown to reduce body weight anywhere from 10-20%, depending on which GLP-1 agonist is used. This is seen especially when a GLP-1 agonist is used with diet and regular exercise. For example, in the SURMOUNT-1 Trial, people taking Mounjaro over 72 weeks noticed an average reduction in body weight of 15% (4).

Though these medications are very effective for weight loss, Qsymia may still be a better option for those who wish to avoid injectable medications. Qsymia is often more affordable, depending on your particular insurance plan.

Qsymia Side Effects

The most common side effects occur in around 5% of people taking Qsymia. This includes:

  • Paraesthesia
  • Dizziness
  • Dysgeusia
  • Insomnia
  • Constipation
  • Dry mouth

Qsymia Dosage and Administration

Qsymia is given as a once-daily oral capsule taken in the morning without food. You should not take Qsymia in the evening as it may cause insomnia. It is started at a dose of 3.75mg/23mg (phentermine 3.75mg/topiramate 23mg) for 14 days. After 14 days, it is increased to the recommended dose of 7.5mg/46mg. It can be gradually increased based on how well you tolerate the medication or if you are seeing results. The maximum dose of Qsymia is 15 mg/92mg.

Qsymia Contraindications and Warnings

Severe Allergic Reaction

You may experience a severe allergic reaction to Qsymia when first taking it. Signs of a severe allergic reaction include swelling of your face, lips, tongue, or throat, problems breathing or swallowing, severe rash or itching, fainting or feeling dizzy, and very rapid heartbeat. Let your provider know immediately if you have experienced this when taking Qsymia in the past.


A serious condition affecting the eye called Acute Angle Closure Glaucoma has been reported in people who take Topiramate, which is a component of Qsymia. Acute Angle Closure Glaucoma has the potential to damage vision if not treated early on permanently. Therefore, if you have a history of glaucoma, then you should avoid Qsymia.

Acute Angle Closure Glaucoma symptoms include decreased vision or severe eye pain around one hour after taking Qsymia. If you experience these symptoms, notify your provider and visit the nearest medical facility.

Arrhythmias or Fast Heart Rate (Tachycardia)

Qsymia can increase your heart rate due to the component, Phentermine. This can be dangerous for those with a history of arrhythmias like atrial fibrillation, atrial flutter, and supraventricular tachycardia (SVT). For this reason, Qsymia should not be given to these patients.


Qsymia should be avoided for those with a history of hyperthyroidism and taking Levothyroxine. Since both medications can raise the heart rate, it could lead to troubles with the heart.

Drug Interactions

Qsymia should not be combined with Monoamine Oxidase Inhibitors like Marplan, Nardil, Emsam, and Parnate.


Qsymia should not be taken if you are pregnant or planning to become pregnant. Qsymia can cause fetal harm and malformations during early pregnancy.

Qsymia Coverage and Cost

The average retail cost for Qsymia is around $250 for a month's supply. Since Qsymia has been on the market for some time and has been approved for weight loss, it is more likely to be covered by insurance. You can use the following link to see if your insurance plan covers Qsymia. There is also a Qsymia Savings Card where you can pay up to $70 for the first copay, and then the card covers up to $65 of the remaining cost.

Where Can I Get Qsymia?

If you want to learn more about Qsymia or if you might be eligible for medication-assisted weight loss, check out Mochi Health, where board-certified obesity medicine physicians can offer expertise in this realm!

Mochi Health is a virtual obesity medicine practice that connects you with medical providers, like licensed physicians and nurse practitioners, to help you optimize your weight loss journey. We provide monthly video chats with actual medical providers to provide guidance about weight management and to get you started on prescription weight loss medications to supplement your weight loss plan.


  1. Gadde KM, Allison DB, Ryan DH, Peterson CA, Troupin B, Schwiers ML, Day WW. Effects of low-dose, controlled-release, phentermine plus topiramate combination on weight and associated comorbidities in overweight and obese adults (CONQUER): a randomized, placebo-controlled, phase 3 trial. Lancet. 2011 Apr 16;377(9774):1341-52. doi: 10.1016/S0140-6736(11)60205-5. Epub 2011 Apr 8. Erratum in: Lancet. 2011 Apr 30;377(9776):1494. PMID: 21481449.
  2. Garvey WT, Ryan DH, Look M, Gadde KM, Allison DB, Peterson CA, Schwiers M, Day WW, Bowden CH. Two-year sustained weight loss and metabolic benefits with controlled-release phentermine/topiramate in obese and overweight adults (SEQUEL): a randomized, placebo-controlled, phase 3 extension study. Am J Clin Nutr. 2012 Feb;95(2):297-308. doi: 10.3945/ajcn.111.024927. Epub 2011 Dec 7. PMID: 22158731; PMCID: PMC3260065.
  3. Allison DB, Gadde KM, Garvey WT, Peterson CA, Schwiers ML, Najarian T, Tam PY, Troupin B, Day WW. Controlled-release phentermine/topiramate in severely obese adults: a randomized controlled trial (EQUIP). Obesity (Silver Spring). 2012 Feb;20(2):330-42. doi: 10.1038/oby.2011.330. Epub 2011 Nov 3. PMID: 22051941; PMCID: PMC3270297.
  4. Apovian, C.M., Aronne, L., Rubino, D., Still, C., Wyatt, H., Burns, C., Kim, D., Dunayevich, E. and (2013), A randomized, phase 3 trial of naltrexone SR/bupropion SR on weight and obesity-related risk factors (COR-II). Obesity, 21: 935-943. https://doi.org/10.1002/oby.20309
  5. Jastreboff AM, Aronne LJ, Ahmad NN, Wharton S, Connery L, Alves B, Kiyosue A, Zhang S, Liu B, Bunck MC, Stefanski A; SURMOUNT-1 Investigators. Tirzepatide Once Weekly for the Treatment of Obesity. N Engl J Med. 2022 Jul 21;387(3):205-216. doi: 10.1056/NEJMoa2206038. Epub 2022 Jun 4. PMID: 35658024.

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