Topiramate for weight loss: side effects, dosage, and more

You may have heard of topiramate if you're looking into medications to support your weight loss efforts. Originally developed for managing epilepsy and migraines, some evidence suggests topiramate may help curb appetite, boost fat burning, and reduce binge eating behavior. 

What does the research say about topiramate for weight loss? Ahead, we explore the science behind topiramate and discuss its potential benefits for those seeking a comprehensive approach to weight management.

Topiramate, which is also available under the brand name Topamax, is an anticonvulsant medication approved by the US Food and Drug Administration (FDA) for treating epilepsy, including tonic-clonic and partial-onset seizures, and preventing migraines. It calms excessive electrical activity in the brain, helping control and stabilize abnormal nerve signals that may trigger seizures or migraines. 

Topiramate also has numerous off-label uses, including treating

• psychotropic drug-induced weight gain, such as  that caused by antidepressants or mood stabilizers

• binge eating disorder, a psychological condition characterized by episodes of uncontrolled consumption of lots of food in a short period of time 

• obesity with hypertension (high blood pressure). 

The drug is available in several forms for oral use, including tablets, sprinkle capsules (small beads containing medication you can sprinkle on food), extended-release capsules for longer-lasting effects, and a liquid solution.

Topamax isn’t the only brand-name drug featuring topiramate. Others include Qudexy XR, Trokendi XR, and Eprontia. You can also find it in Qsymia, an FDA-approved weight loss medication that contains both topiramate and phentermine—but more on that later. For now, we’ll focus on  topiramate as a generic medication and as the active ingredient of Topamax. 

Although the exact mechanisms are not fully understood, research suggests that topiramate may promote weight loss in several ways. 

• Reduces appetite. Topiramate can affect certain neurotransmitters in the brain, such as gamma-aminobutyric acid (GABA), which controls hunger and helps reduce appetite. 

• Alters food reward pathways. Topiramate may influence the brain's reward system and alter the perception of hunger and fullness, helping decrease the desire to overeat. 

• Increases fat burning. Topiramate can stimulate thermogenesis—the process of heat production in the body—and promote fat oxidation—the breakdown of fat for energy. This makes it easier for the body to break down and use fats for energy rather than storing them, potentially contributing to weight loss. 

• Regulates hormones. Topiramate may affect the levels of certain hormones involved in weight and appetite. Some studies suggest that topiramate can lower levels of leptin, a hormone that helps regulate appetite and body weight. One study found that leptin levels dropped by 36% after three months in people with epilepsy who lost 10% or more of their weight while taking topiramate. This study also found a gradual reduction in body fat among people with obesity. 

The time it takes for topiramate to show noticeable weight loss effects can vary from person to person. Research suggests the most substantial weight loss occurs 3–6 months after starting topiramate, with some people continuing to lose weight beyond this period. 

In one study, 701 people with obesity first followed a low-calorie diet for eight weeks. Those who lost at least 8% of their body weight were then given topiramate or a placebo and continued following a low-calorie diet. After 44 weeks, the topiramate group continued losing weight—up to 16.5% of their starting weight—while the placebo group regained some weight.

Another study involving people with obesity or overweight and hypertension found that those who took topiramate lost 5.9–6.5% of their body weight after 24 weeks compared to 1.9% for the placebo group. 

There is no standard topiramate dosage for weight loss. That said, 96 mg–192 mg of topiramate per day has been found to be an effective range for weight loss, according to one study. And while higher doses of the drug have been shown to produce more significant results, they’re more likely to cause an increase in side effects. 

If prescribed topiramate for weight loss, your healthcare provider will likely start you on a low dose (e.g. 25 mg per day) for at least a week. From there, if it’s appropriate, your provider will gradually increase your dose weekly until a suitable maintenance dose—i.e. an amount that allows you to see desired effects from the drug while being able to tolerate side effects, if any. This amount can be anywhere from 50 mg to 400 mg per day. But some research suggests the maximum dose of the drug should be 100 mg per day when prescribed for weight loss. 

Topiramate is taken orally (by mouth) with or without food. Swallow topiramate tablets and capsules whole. If you have trouble swallowing pills, you can mix sprinkle or extended-release capsules (Qudexy XR brand only) with soft food like applesauce. 

There isn't a universal best time to take topiramate for weight loss, but it's important to take it at the same time every day. Depending on your preference and schedule, this may be in the morning or evening. Some people may find it helpful to take topiramate in the evening. This is because some common side effects, such as fatigue or delayed reaction times, can be easier to manage at night. Always take topiramate as directed by your healthcare provider. 

While topiramate can be an effective tool for weight loss, it also comes with potential side effects, especially at higher doses. Common side effects of the drug include:  

• Tingling in the hands and feet (paresthesia) 

• Drowsiness or fatigue 

• Dizziness or lightheadedness 

• Memory problems or difficulty finding words

• Loss of appetite 

• Nausea 

• Diarrhea 

• Altered sense of taste 

• Agitation or irritability 

In many cases, topiramate side effects are most noticeable when starting the medication or increasing the dose. They usually decrease over time as your body adjusts to the medication. 

Although less common, some people experience more severe adverse reactions to topiramate, such as: 

• Kidney stones, hard deposits of minerals in the kidneys that can cause back or flank (side) pain, bloody, cloudy, or smelly urine, and nausea and vomiting 

• Metabolic acidosis, a condition in which too much acid is in the bloodstream, leading to irregular heartbeat, fatigue, and confusion and increasing the risk of kidney stones and bone weakening

• Vision changes and problems, such as sudden nearsightedness (acute myopia) and increased pressure in the eyes

• Suicidal ideation

• Birth defects, if used during pregnancy, such as cleft palate or cleft lip.

While topiramate is generally safe and well-tolerated, it is not suitable for everyone. You should avoid topiramate or discuss the risks of the drug with your healthcare provider if you:

• Are pregnant or plan on becoming pregnant

• Are breastfeeding

• Have a history of kidney problems (e.g. kidney stones) or kidney disease

• Have glaucoma or other eye conditions

• Have liver disease 

• Struggle with depression or mood problems

Topiramate can decrease the effectiveness of certain medications or increase the risk of adverse side effects when taken with some drugs. While not a complete list of drug interactions, your healthcare provider may not recommend topiramate in combination with the following: 

• Hormonal contraceptives (i.e. birth control pills)

• Carbonic anhydrase inhibitors (e.g. acetazolamide, zonisamide)

• Benzodiazepines (anti-anxiety medications)

• Amitriptyline (antidepressant)

• Lithium (mood stabilizer)

As mentioned above, topiramate can be found in Topamax and Qsymia—both of which are brand-name drugs that can support weight loss. The two differ in their formulations, mechanisms of action, and indications.

• Topamax is primarily an anticonvulsant for treating seizures and preventing migraines, but is sometimes prescribed off-label for weight loss due to its appetite-suppressing effects. When used alone, it can affect brain signals that control hunger and cravings, helping people reduce their calorie intake.

• Qsymia is a combination weight loss drug containing both topiramate and phentermine, a stimulant that helps suppress appetite. It is FDA-approved for weight loss and is prescribed to people with a body mass index (BMI) of 30 or greater (obesity) or 27 and above (overweight) if they have other conditions like diabetes or high blood pressure. Adding phentermine enhances the effects of weight loss by boosting energy and reducing appetite.

For weight loss, Qsymia may be more effective than Topamax because it combines the benefits of both topiramate and phentermine, leading to greater appetite suppression. However, some people may not be able to tolerate phentermine due to its stimulant effects, in which case Topamax alone may be prescribed as an alternative.

Topiramate can be an effective tool for weight loss, particularly when combined with lifestyle changes like a healthy diet and regular exercise. While it is not FDA-approved as a weight loss medication, it is commonly prescribed off-label for this purpose, and studies show it can lead to significant, sustained weight loss over time. 

It’s important to weigh (pun intended) both the potential pros and cons, as side effects such as tingling, fatigue, and, in some cases, more serious issues like kidney stones or mood changes can occur. Ultimately, though, topiramate can be a helpful option for weight loss, but it should be used under the guidance of a healthcare provider to ensure safety and effectiveness.

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Current version

October 15, 2024

Written by

Lindsay Curtis

Fact checked by

Patricia Weiser, PharmD

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About the medical reviewer

Patricia Weiser, PharmD

Patricia Weiser, PharmD, is a licensed pharmacist, health content writer, and medical reviewer with more than a decade of clinical experience in community and hospital pharmacy.