Topiramate (Topamax) for Weight Loss: How It Works, Risks, and Alternatives

With so many new weight loss medications making headlines, it’s easy to feel overwhelmed about where to start. One option you may not have heard much about is topiramate (Topamax)—a medication originally used to treat seizures and migraines that has also helped some people lose weight.

While topiramate isn’t officially approved for weight loss, healthcare providers may prescribe it off-label for this purpose (meaning the medication is legally prescribed for a purpose other than its originally approved use). A recent study showed that 32.5% of patients were prescribed topiramate as a cost-effective strategy to prevent weight regain after stopping GLP-1 medications.

Read on to learn how topiramate may influence weight, what results people typically see, and the key factors your provider will consider when deciding if it’s right for you.

What is topiramate (Topamax)?

Topiramate is an antiepileptic medication. It's prescribed to treat tonic-clonic and partial-onset seizures in children aged 2 years and older. It is also FDA-approved to prevent migraines in adults and children over 12.

Topiramate is not FDA-approved as a weight loss medication on its own—although providers may prescribe it off-label.

However, when combined with another drug called phentermine as the brand-name drug Qsymia, it is FDA-approved as a weight loss medication for:

• Adults and pediatric patients aged 12 years and older with obesity (a BMI of 30 or greater)
• Adults who are overweight (a BMI of 27 or greater) and at least one weight-related condition, like type 2 diabetes or high blood pressure

It is important to know that Qsymia is classified as a Schedule IV controlled substance. This means that getting a prescription through a telehealth provider may not be easy.

Federal rules currently allow controlled substances to be prescribed online. However, some states strictly prohibit providers from prescribing this medication over telehealth entirely, or require you to have an initial, in-person physical exam first. Your provider will have to verify the specific laws of your state.

Topiramate is currently being studied for its efficacy in treating alcohol use disorder (alcoholism), post-traumatic stress disorder (PTSD), bipolar disorder, and binge eating disorder.

Topiramate is available as immediate-release (IR) oral tablets, extended-release (XR) oral capsules, and IR sprinkle capsules that can be opened and mixed into soft foods.

How does topiramate for weight loss work?

The exact way that topiramate causes weight loss is not fully understood. Studies suggest that topiramate may cause weight loss by lowering your appetite, which can lead to a lower calorie intake. It may also prevent your body from storing excess fat, lower some fat and cholesterol levels, and affect the brain's reward system, which can potentially prevent binge eating.

Topiramate may also influence fat storage by targeting leptin, the hormone that signals fullness to your brain. By regulating fluctuating leptin levels, topiramate can help reset your body's appetite cues and support consistent weight loss.

Topiramate can also help by turning down neuropeptide Y—a chemical in the brain that drives intense hunger—and blocking an enzyme called carbonic anhydrase to change how your body processes sugars and fats. This makes it much harder for your system to build and store new fat cells.

Is topiramate effective for weight loss?

Topiramate has been shown to cause meaningful, but not dramatic, weight loss in some patients. How much weight you lose may depend on whether you take topiramate alone or in combination with phentermine. It may also depend on your baseline BMI and how long you take it for.

In several studies, patients taking topiramate alone lost an average of around 5 to 10% of their body weight over 6 to 12 months. One clinical trial showed that patients lost more weight if they started with a higher BMI and took topiramate for longer.

Topiramate-phentermine as a combination seems to cause more weight loss than topiramate (or phentermine) alone. Studies showed patients taking this combination lost an additional 5% or more on average compared to those who took similar doses of topiramate or phentermine only.

What's the best topiramate dosage for weight loss?

Topiramate for weight loss is usually started from a low dose (around 25 to 50 mg per day or lower). Over several weeks or months, a provider may gradually step the dosage up to 100 mg or 200 mg per day (typically split into two doses). This slow increase allows your body to adjust, significantly lowering the risk of common side effects like dizziness, fatigue, and finger tingling.

Because topiramate alone is not FDA-approved for weight loss, there is no official FDA-recommended dosage for this off-label use.

The usual starting dose for Qsymia, the FDA-approved topiramate-phentermine combination for weight loss, is 3.75/23 mg (phentermine/topiramate). This is taken daily for 14 days to help your body adjust before stepping up to the standard recommended dose of 7.5/46 mg.

Do not stop taking topiramate suddenly. Because it is an anti-seizure medication, stopping abruptly can trigger sudden, dangerous seizures—even if you have never had one before. If you need to stop, your healthcare provider must give you a safe schedule to taper off slowly.

Talk to your provider if you experience side effects. They may reduce your dosage or prescribe an alternative treatment option in this event.

What's the best time to take topiramate for weight loss?

Topiramate is usually taken once or twice daily for its FDA-approved uses. Your provider may recommend taking a single dose at night during the first week of treatment. This may help you sleep through the initial side effects, like drowsiness or dizziness, while your body adjusts to the medication.

Qsymia is taken once daily in the morning because one of the active ingredients, phentermine, is a stimulant. Taking it in the afternoon or evening can cause insomnia.

How long does topiramate take to work for weight loss?

In studies, weight loss became noticeable in as little as 1 month after patients started taking topiramate by itself. Clinical trials show that phentermine-topiramate produces meaningful weight loss within the first 3 months of treatment. Most of the total weight loss is achieved by the one-year mark.

In one large study, patients taking topiramate alone lost an average of 11 to 15 pounds over roughly 4 to 7 months or more.

A study of patients taking phentermine-topiramate lost 20 to 32 pounds over about a year, depending on the dose.

In general, higher doses of topiramate are shown to cause more significant weight loss. However, higher doses are also linked to a higher risk of side effects.

Who should take topiramate for weight loss?

Healthcare providers may consider topiramate for weight loss if you meet the standard criteria: a BMI of 30 or higher, or a BMI of 27 or higher paired with a weight-related condition like high blood pressure or type 2 diabetes.

Talk to your healthcare provider about whether or not topiramate is right for you and your condition.

Is topiramate safe?

Topiramate is generally considered safe and effective for most adults and children over the age of 12, if prescribed by a licensed healthcare professional. However, like any medication, it can cause side effects in some patients.

Common side effects of topiramate include:

• Burning, numbness, or tingling in your feet, hands, face, or mouth (paresthesia)
• Dry mouth or altered taste
• Constipation, nausea, or stomach pain
• Dizziness, drowsiness, or slowed reactions
• Nervousness
• Headache
• Shaking or muscle weakness
• Nosebleeds
• Involuntary eye movements
• Menstrual irregularities

Avoid alcohol and other central nervous system (CNS) depressants, such as sedatives and certain pain medications, as they can increase these side effects.

Get emergency care right away if you experience:

• Severe skin reactions: A sudden rash, blisters, or peeling
• Sudden vision problems: Blurred vision, loss of vision, double vision, eye pain, redness
• Neurological emergencies: A new or worsening seizure, severe coordination problems, confusion, or an inability to respond to your surroundings (coma)
• Cardiovascular symptoms: Chest pain, a pounding or irregular heartbeat, or severe shortness of breath

Contact your healthcare provider promptly if you experience:

• Kidney problems: Intense lower back or side pain, blood in your urine, painful urination, or unusually frequent urination
• Cognitive changes: Persistent difficulty concentrating, speech problems, or ongoing memory issues.
• Metabolic issues: Feeling constantly cold, chills, or a low body temperature (signs of metabolic acidosis)
• Severe gastrointestinal changes: Persistent diarrhea, vomiting, or a total loss of appetite
• Systemic changes: Unexplained tiredness, a fever or other signs of infection, unusual bleeding, bruising, or long-term concerns like osteoporosis

In general, higher doses of topiramate are associated with an increased risk of adverse reactions.

What precautions should I take before taking topiramate?

Before starting treatment with topiramate, tell your provider about any medical conditions you have, any medications or supplements you are taking, and any adverse reactions to medicines in the past. Topiramate may reduce the efficacy of certain medications, such as birth control pills.

Healthcare providers may avoid prescribing topiramate for individuals with a history of:

• Suicidal thoughts or behaviors
• Kidney stones
• Metabolic acidosis
• Bone conditions like osteopenia, osteomalacia, or osteoporosis
• Glaucoma
• Respiratory issues like asthma or COPD
• Depression or mood disorders
• Growth problems
• Thyroid, liver, or kidney disease

Because topiramate can increase the risk of kidney stones, it’s important to stay well-hydrated while taking the medication. Drink plenty of water, and ask your healthcare provider whether you should take supplements like potassium citrate to lower your kidney stone risk.

Tell your provider if you are following a ketogenic diet (a high-fat, low-carbohydrate diet that is sometimes used to control seizures). Taking topiramate while on a ketogenic diet can increase your risk of metabolic acidosis (a chemical imbalance where there is too much acid in the bodily fluids).

Your provider may not prescribe you topiramate if you are pregnant, trying to conceive, or breastfeeding.

Are there alternatives to topiramate?

Yes, there are alternatives to topiramate if your goal is weight loss. Depending on your BMI and health history, your provider might recommend medications that are specifically FDA-approved for weight management. Alternatively, they may prescribe other drugs off-label because weight loss is a known side effect.

Always talk to your healthcare provider before starting a new medication. Here are a few alternatives to topiramate:

• Semaglutide (Ozempic, Wegovy, Rybelsus): Semaglutide is a diabetes drug that assists with weight loss when prescribed with a healthy diet and regular exercise. Semaglutide works by managing blood sugar levels, curbing appetite, and slowing stomach emptying (which makes you feel fuller longer). Wegovy, a brand-name medication containing semaglutide, is specifically approved for the treatment of obesity in patients without type 2 diabetes.
• Tirzepatide (Mounjaro, Zepbound): Tirzepatide is a type of medication called a GLP-1/GIP receptor agonist. It is available as Mounjaro, an FDA-approved diabetes medication, and Zepbound, an FDA-approved weight loss medication. Tirzepatide controls your blood sugar levels, reduces your appetite, and slows your stomach emptying.
• Liraglutide (Victoza, Saxenda): Liraglutide is a type of GLP-1 receptor agonist approved by the FDA to treat obesity in adults and children over 12. It works largely the same way as semaglutide but is only available as a once-daily injection.
• Naltrexone/bupropion (Contrave): Naltrexone works as an opioid receptor antagonist, which can reduce the rewarding effects of food and cravings, particularly for high-calorie, high-sugar foods. Bupropion helps lower your appetite and make you feel fuller, making it easier to control your calorie intake. Contrave is FDA-approved as a weight management aid for patients with obesity or individuals who are overweight and have a weight-related health condition.
• Metformin: Metformin is a prescription diabetes drug that has been shown to cause modest weight loss in some patients. It works by improving your blood sugar levels and how your body responds to insulin.

Frequently asked questions

Why is topiramate used in combination with phentermine?

Topiramate and phentermine are combined into a single medication (brand name Qsymia) because they target appetite suppression through two completely different biological pathways. Phentermine can reduce immediate hunger signals and reduce cravings, while topiramate reduces the reward sensation of eating and helps you feel full for longer after a meal.

Is topiramate a controlled substance?

No, topiramate by itself is not a controlled substance. Topiramate requires a prescription, but unlike opioids or benzodiazepines, it carries no risk of abuse, addiction, or physical dependence. The topiramate-phentermine combination Qsymia, however, is a Schedule IV controlled substance.

What is the difference between topiramate (Topamax) and phentermine-topiramate (Qsymia)?

Topamax and phentermine-topiramate have different main active ingredients and FDA-approved uses:

• The main active ingredient in Topamax is topiramate. The main active ingredients in Qsymia are phentermine and topiramate.
• Topiramate is FDA-approved for epilepsy and migraine prevention only. Qsymia is FDA-approved as a weight loss drug for adults with a BMI of 30 or greater, or a BMI of 27 or greater and a weight-related health condition. ### Why am I not losing weight on Topamax? If you aren't losing weight on topiramate, your dose may be too low or you may be a clinical "non-responder". Medical guidelines state the drug is unlikely to work long-term if you haven't lost 3% to 5% of your starting weight after 12 weeks on a full dose.

Studies also show that progress is naturally slower for those with a lower starting BMI. Consult your provider to discuss a safe dose adjustment or an alternative treatment.

Can you gain weight on Topamax?

Yes, you can gain weight while taking Topamax, but it is rare. Talk to your healthcare provider if you notice weight gain while taking this medication. They can evaluate your health profile and give you personalized advice and recommendations.

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