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

While it’s not approved by the US Food and Drug Administration (FDA) for weight loss, topiramate can be prescribed off-label for that use. In fact, evidence suggests it may help curb appetite, boost fat burning, and reduce binge eating behavior.

Topiramate is FDA-approved for weight loss only when combined with phentermine as Qsymia, a once-daily pill used alongside lifestyle changes.

This article will cover what you need to know about topiramate for weight loss, including how long it takes to work, dosages, side effects, costs, and more. 

Topiramate, which is also available under the brand name Topamax, is an anticonvulsant medication FDA-approved 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. For now, we’ll focus on topiramate as a generic medication and as the active ingredient of Topamax.

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Topiramate works for weight loss in several ways, including the following:

• 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 given topiramate or a placebo and continued following the 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. The “best” dose will vary from person to person. 

• 25 mg per day is a common starting dose that your healthcare provider will prescribe for at least a week. From there, if appropriate, your provider will gradually increase your dose weekly until a suitable maintenance dose — an amount that allows you to see desired effects from the drug while being able to tolerate side effects, if any. 

• 50 mg–400 mg per day may be a maintenance dose. But some research suggests the maximum dose of the drug should be 100 mg per day when prescribed for weight loss. 

• Approximately 100 mg–200 mg per day has been found to be an effective range for weight loss, according to one study. 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. 

Topiramate is taken orally (by mouth) with or without food. Swallow topiramate tablets and capsules whole. If you have trouble swallowing pills, you can open the extended-release capsules (Qudexy XR brand only) and sprinkle the contents into a soft food, such as 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 

• Loss of appetite 

• Nausea 

• Diarrhea 

• Altered sense of taste 

• Nervousness

• Upper respiratory infection

• Speech problems

• Slowed reactions

• Abdominal pain

• Abnormal vision

• Fever

• Decreased feeling/sensitivity of the skin

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, nausea, vomiting, and bloody, cloudy, or smelly urine

• Metabolic acidosis, a condition in which too much acid is in the bloodstream, leading to irregular heartbeat, fatigue, and confusion. It can also increase 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 a cleft palate or cleft lip

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)

• Central nervous system depressants (e.g. sedatives, alcohol)

• Amitriptyline (antidepressant)

• Lithium (mood stabilizer) 

• Hydrochlorothiazide (diuretic)

• Certain seizure medications (e.g. carbamazepine, valproate)

The cost of topiramate can vary based on your location, pharmacy, and insurance coverage. However, according to GoodRx: 

• A 30-day supply of 100 mg can cost $6–$41

• A 30-day supply of 200 mg can cost $6–$64

If your provider prescribes you brand-name Topamax, you may qualify for a savings card that can decrease the price to as little as $4. 

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 

• Have weak or brittle bones

• Have breathing or lung problems

• Have a history of metabolic acidosis

• Struggle with depression, mood problems, or suicidal thoughts/behaviors

• Have an upcoming surgery

• Are on a ketogenic diet

• Have diarrhea

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Topiramate can be an effective tool for weight loss, particularly when combined with lifestyle changes, such as a healthy diet and regular exercise. Here’s what to keep in mind when it comes to this drug: 

• While topiramate is not FDA-approved as a weight loss medication, it is commonly prescribed off-label for this purpose. Studies show it can lead to significant, sustained weight loss over time.

• It’s important to weigh both the potential pros and cons of the medication. Consider the risk of side effects, including tingling, fatigue, and dizziness. In some cases, more serious issues like kidney stones or mood changes can occur. 

• Topiramate can be a helpful option for weight loss. But it should be used under a healthcare provider's guidance to ensure safety and effectiveness.