Topamax (topiramate) is a prescription brand-name medication. It’s approved by the Food and Drug Administration (FDA) to:

You’ll likely take Topamax long-term, if you and your doctor agree that it’s working well for you.

Here are some fast facts on Topamax:

  • Active ingredient: topiramate
  • Drug class: anticonvulsant
  • Drug form: oral tablet

Like other drugs, Topamax can cause side effects. Read on to learn about potential common, mild, and serious side effects. For a general overview of Topamax, including details about its uses, see this article.

Topamax can cause certain side effects, some of which are more common than others. These side effects may be temporary, lasting a few days or weeks. But if the side effects last longer than that, bother you, or become severe, be sure to talk with your doctor or pharmacist.

These are just a few of the more common side effects reported by people who took Topamax in clinical studies. These side effects can vary depending on which condition the drug is being used to treat.

More common side effects in people taking Topamax for epilepsy include:

More common side effects in people taking Topamax to prevent migraine headaches include:

  • feelings of burning or numbness in your hands and feet
  • appetite loss
  • weight loss*
  • memory problems
  • changes in taste*

* For more information about this side effect, see “Side effect specifics” below.

Mild side effects can occur with Topamax use. This list doesn’t include all possible mild side effects of the drug. For more information, you can refer to Topamax’s medication guide.

Mild side effects that have been reported with Topamax include:

These side effects may be temporary, lasting a few days or weeks. But if the side effects last longer than that, bother you, or become severe, be sure to talk with your doctor or pharmacist.

Note: After the Food and Drug Administration (FDA) approves a drug, it tracks side effects of the medication. If you develop a side effect while taking Topamax and want to tell the FDA about it, visit MedWatch.

* This side effect can affect your ability to drive or safely operate machinery. You should avoid these activities until you know how Topamax affects you.
† For more information about this side effect, see “Side effect specifics” below.

Topamax may cause serious side effects. The list below may not include all possible serious side effects of the drug. For more information, you can refer to Topamax’s medication guide.

If you develop serious side effects while taking Topamax, call your doctor right away. If the side effects seem life threatening or you think you’re having a medical emergency, immediately call 911 or your local emergency number.

Serious side effects that have been reported and their symptoms include:

  • Hyperthermia (decreased sweating and increased body temperature). Symptoms can include:
    • heat intolerance
    • producing less sweat than normal
  • Metabolic acidosis (increased acid levels in your blood). Symptoms can include:
    • changes in your heart rate
    • trouble thinking clearly
    • feeling more tired than usual
  • Serious skin reactions, including Stevens-Johnson syndrome and toxic epidermal necrolysis. Symptoms can include:
    • body aches
    • trouble swallowing
    • painful skin
    • peeling skin, with or without blisters
  • High blood levels of ammonia (a waste product made by your body), which may cause swelling in your brain. Symptoms can include:
    • coordination problems
    • headache
    • irritability
    • vomiting
  • Kidney stones. Symptoms can include:
    • blood in your urine
    • painful urination
    • sharp pain in your back or lower abdomen (belly)
  • Eye problems.*
  • Mood changes, including suicidal thoughts.*
  • Cognitive side effects.*
  • Allergic reaction.*

* For more information about this side effect, see “Side effect specifics” below.
† An allergic reaction is possible after using Topamax. But it’s not clear whether this side effect occurred in clinical studies.

Most Topamax side effects aren’t permanent, and go away with time. For example, fatigue (low energy) and feelings of burning or numbness in your hands and feet may go away as you continue taking Topamax. Your doctor may prescribe a temporary treatment to help you manage these side effects for a short period of time.

Some rare side effects caused by Topamax may require treatment to make them go away. These side effects may include kidney stones and high blood levels of ammonia (a waste product made by your body). Some side effects can cause long-term effects if they aren’t treated, such as increased pressure in your eye. Make sure to contact your doctor right away if you have symptoms that are severe or bother you.

If you have side effects that won’t go away or are hard to deal with, your doctor will likely have you stop taking Topamax. This should cause side effects of the drug to go away.

Topamax may cause several side effects. Here are some frequently asked questions about the drug’s side effects and their answers.

Do Topamax’s side effects vary based on which strength or dosage of the drug I’m taking?

Possibly. In clinical studies, how often certain side effects occurred varied depending on which dose of Topamax was taken.

For example, the following side effects were more likely to happen with higher doses (200 mg) of Topamax (compared with 25 mg or 50 mg, for example):

For details about side effects in studies, you can see Topamax’s prescribing information. You can also talk with your doctor or pharmacist.

Could a missed dose of Topamax cause side effects?

No, missing a dose of Topamax won’t cause side effects.

However, missing doses may cause you to have symptoms of the condition you’re using Topamax to treat. For example, missing Topamax doses could cause you to have a migraine headache.

To help make sure that you don’t miss a dose, try using a medication reminder. This can include setting an alarm or using a timer. You could also download a reminder app on your phone.

Can Topamax’s side effects vary depending on how it’s used?

It’s possible. Side effects in clinical studies were slightly different depending on whether people used the drug to treat seizures or to prevent migraine headaches. It’s important to note that the dosage of Topamax is higher for seizures than for migraine headache prevention. This may make some side effects more likely.

For a list of side effects that were more common for each of these uses, see the “More common side effects” section above. You can also see Topamax’s prescribing information or talk with your doctor or pharmacist.

Learn more about some of the side effects that Topamax may cause, as well as some tips for dealing with or helping to stop side effects.

Eye problems

Although not common, Topamax can cause eye problems. These may include:

Symptoms of eye problems caused by Topamax can include:

  • blurry vision
  • dilated pupils (the black part of your eye being larger than usual)
  • eye pain
  • eye redness
  • sudden decrease in vision

What you can do

Contact your doctor right away if you have symptoms of eye problems while taking Topamax. They’ll recommend whether you should stop taking the drug. They may also recommend that you see an eye doctor.

In most cases, eye side effects go away if you stop taking the drug. But you should not stop taking Topamax unless your doctor recommends this.

Mood shifts

Topamax can cause shifts or changes in mood, including suicidal thoughts. These were rare in clinical studies.

Examples of behavior and mood shifts Topamax can cause include:

Symptoms to watch for include:

  • feeling agitated, aggressive, or irritable
  • feeling anxious or having panic attacks
  • feeling hopeless or sad
  • losing interest in activities you normally enjoy
  • trouble sleeping or sleeping too much

What you can do

If you have any unusual shifts in mood while taking Topamax, contact your doctor right away. They may be able to suggest ways to ease your symptoms. Or they may recommend switching from Topamax to a different treatment for your condition. And if you experience suicidal thoughts, it’s important to get help right away.

Weight loss

It’s possible to have weight loss from taking Topamax. This side effect was somewhat common in clinical studies. (The average amount of weight lost in these studies wasn’t noted.)

What you can do

Talk with your doctor if you’re concerned about your weight while taking Topamax. They can suggest ways to maintain a weight that’s healthy for you.

Cognitive side effects

Treatment with Topamax can cause a variety of cognitive side effects. This refers to side effects that affect how you think. Some of these side effects are mild, while others can be more serious.

Cognitive side effects of Topamax can include:

  • confusion
  • trouble concentrating
  • fatigue (low energy)
  • memory problems
  • sleepiness
  • slow reaction time
  • speech problems
  • mood changes (see “Mood changes” just above)

Your risk for cognitive side effects from Topamax increases if you start with a high dose, or your dose is increased quickly.

What you can do

Talk with your doctor if you experience cognitive side effects while taking Topamax. They can recommend next steps based on the symptoms you’re having. It’s important to not change your dosage of Topamax without first talking with your doctor.

Hair loss

Taking Topamax can cause hair loss as a side effect. This side effect wasn’t common in clinical studies and was only reported by people taking the drug for epilepsy. People taking Topamax to prevent migraine headaches didn’t report hair loss.

What you can do

Talk with your doctor if you have hair loss while taking Topamax. They may recommend a treatment. Or they may suggest you stop taking Topamax and try a different treatment for your condition.

Changes in taste

You may have changes in your sense of taste as a result of taking Topamax. This can cause things to taste unusual or bad.

Changes in taste was a common side effect reported by people who took Topamax for preventing migraine headaches in clinical studies. This was also reported by people taking the drug to treat epilepsy, but it was less common.

What you can do

Contact your doctor if you have changes in taste while taking Topamax. They’ll likely recommend you stop taking the drug and try another treatment for your condition.

Allergic reaction

As with most drugs, Topamax can cause an allergic reaction in some people. However, it isn’t known how often this side effect may have occurred in clinical studies.

Symptoms can be mild or serious and can include:

  • skin rash
  • itching
  • flushing (temporary warmth, redness, or deepening of skin color)
  • swelling under your skin, typically in your lips, eyelids, feet, or hands
  • swelling of your mouth, tongue, or throat, which can make it hard to breathe

What you can do

For mild symptoms of an allergic reaction, call your doctor right away. They may recommend ways to ease your symptoms and determine whether you should keep taking Topamax. But if your symptoms are serious and you think you’re having a medical emergency, immediately call 911 or your local emergency number.

For the most part, side effects of Topamax in children are similar to those in adults. These side effects are described above.

However, compared to adults, children taking Topamax may be more likely to have certain side effects, including:

It’s important to keep an eye on your child in hot weather. If they have a high temperature or if they sweat less than usual, contact their doctor right away. A high temperature for children ages 2 years and older is above 99.5°F (37.5°C).

Children are less likely than adults to experience the following side effects from Topamax:

  • trouble concentrating
  • slow reaction time
  • speech problems

Talk with your child’s doctor, or a pharmacist, if you have questions about Topamax’s side effects in children.

Be sure to talk with your doctor about your health history before you take Topamax. This drug may not be the right treatment for you if you have certain medical conditions or other factors that affect your health. The conditions and factors to consider include:

Bone problems, such as osteoporosis. Topamax can rarely cause metabolic acidosis (too much acid in your blood). If untreated, this condition can lead to bone problems, including osteoporosis (weakened bones). You may be at higher risk of bone complications from metabolic acidosis if you already have bone problems. Your doctor can help determine whether treatment with Topamax is safe for you.

Breathing or lung problems. If you have breathing problems or lung problems, you may be at increased risk of metabolic acidosis if you take Topamax. These problems include chronic obstructive pulmonary disease (COPD). Your doctor can help determine whether treatment with Topamax is safe for you.

Depression or suicidal thoughts. Topamax can increase your risk of depression and suicidal thoughts or actions. You may be at higher risk if you already experience depression or suicidal thoughts. Your doctor can help determine whether treatment with Topamax is safe for you.

Glaucoma. Although rare, treatment with Topamax can cause a condition called secondary closed-angle glaucoma. If you have glaucoma, Topamax may not be safe for you to take. Your doctor can help determine whether treatment with Topamax is safe for you.

Diarrhea. Having diarrhea while taking Topamax can increase your risk of metabolic acidosis. Let your doctor know if you have frequent or uncontrolled diarrhea while you’re taking Topamax. You may need blood tests to make sure the level of acid in your blood is safe.

Liver problems. If you have liver problems, such as cirrhosis or hepatitis, you may have an increased risk of high ammonia levels in your blood from taking Topamax. You may need additional blood tests to monitor your levels while you’re taking Topamax. Your doctor can help determine whether treatment with Topamax is safe for you if you have liver problems.

Ketogenic diet. Following a ketogenic (“keto”) diet can increase acid levels in your blood. Increased acid in your blood is also a potential side effect from taking Topamax. For this reason, following a ketogenic diet while taking Topamax usually isn’t recommended. Talk with your doctor about the best diet and treatment for your condition, including whether Topamax is safe for you to take.

Kidney problems. Topamax can rarely cause metabolic acidosis, which can lead to kidney stones if it isn’t treated. If you have kidney problems, such as chronic kidney disease, you have an increased risk of both metabolic acidosis and kidney stones as a complication. Your doctor can help determine whether treatment with Topamax is safe for you if you have kidney problems. If they do decide to prescribe Topamax, they may start you with a lower dose than usual.

Allergic reaction. You should not take Topamax if you’ve ever had an allergic reaction to Topamax or any of its ingredients. Talk with your doctor about which other treatments are better choices for you.

Alcohol use with Topamax

You should not drink alcohol while taking Topamax. Drinking alcohol while taking Topamax can increase your risk of certain side effects and increase the chance that they’ll be serious.

These side effects include:

Talk with your doctor if you have questions about how drinking alcohol can affect treatment with Topamax.

Pregnancy and breastfeeding while taking Topamax

Taking Topamax while pregnant can cause harm to the fetus. Taking Topamax while pregnant increases the child’s risk of a cleft lip or cleft palate. They’re also more likely to be born small for their gestational age. Talk with your doctor about the possible risks and benefits of taking Topamax if you’re pregnant or planning a pregnancy.

If you take Topamax while pregnant, you’re encouraged to sign up with the North American Antiepileptic Drug Pregnancy Registry. This registry helps healthcare professionals collect information about the safety of medications such as Topamax during pregnancy. This can help you make informed decisions about the treatments you take during pregnancy. You can register by visiting the program website or calling 888-233-2334.

Topamax is known to pass into breast milk. The drug can cause side effects such as sleepiness or diarrhea in a breastfed child. Talk with your doctor about the best way to feed your child if you’re taking Topamax.

Like all medications, Topamax can cause side effects. Many are mild and tend to go away on their own after a few days or weeks. But the drug can also cause some serious side effects which may require treatment.

If you’d like to learn more about Topamax, talk with your doctor or pharmacist. They can help answer any questions you have about side effects from taking the drug.

Besides talking with your doctor, you can do some research on your own. These articles might help:

  • More information on Topamax. For details on other aspects of Topamax, refer to this article.
  • Details about Topamax for migraine.See this article for more information about using Topamax to prevent migraine headaches.
  • A look at your condition. For details about migraine, see our migraine hub as well as these related articles. And for more information about epilepsy, see these articles.

Disclaimer: Medical News Today has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or another healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.