Topamax is used to prevent migraine headaches and treat epilepsy in certain people. Below, you’ll find lists of the drug’s more common, mild, and serious side effects.

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. However, 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 trials. These side effects can vary depending on which condition you are taking the drug 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 prescribing information.

Mild side effects that people taking Topamaz have reported include:

  • burning or numbness in your hands and feet
  • appetite loss
  • speech problems
  • fatigue
  • dizziness
  • sleepiness
  • nervousness
  • memory problems
  • slow reaction time
  • diarrhea
  • nausea
  • abdominal pain
  • weight loss*
  • hair loss*
  • changes in how things taste*

These side effects may be temporary, lasting a few days or weeks. However, 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.

* 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 prescribing information.

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 and their symptoms that people taking Topamax have reported include:

  • Hyperthermia (decreased sweating and increased body temperature). Symptoms can include:
    • body temperature that’s higher than usual
    • heat intolerance
    • producing less sweat than usual, especially in hot weather
  • Metabolic acidosis (increased acid levels in your blood). Symptoms can include:
    • changes in your heart rate
    • trouble thinking clearly
    • feeling more tired than usual
    • appetite loss
  • Serious skin reactions, including Stevens-Johnson syndrome and toxic epidermal necrolysis. Symptoms can include:
    • body aches
    • trouble swallowing
    • fever
    • 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
    • seizures
    • vomiting
  • Kidney stones. Symptoms can include:
    • blood in your urine
    • nausea and vomiting
    • painful urination
    • sharp pain in your back or lower abdomen
  • Eye problems.*
  • Mood changes, including suicidal thoughts.*
  • Cognitive side effects.*

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

Allergic reaction

For some people, Topamax can cause an allergic reaction. But it’s unclear whether this side effect occurred in the drug’s studies.

In general, symptoms of allergic reaction can be mild or serious.

Ways to manage

For mild allergic reaction symptoms, such as a mild rash, call your doctor right away. They may recommend treatments to help manage your symptoms. They’ll also let you know whether you should keep taking the medication.

For severe allergic reaction symptoms, such as swelling or trouble breathing, call 911 or your local emergency number right away. These symptoms require immediate medical care because they can become life threatening. If you’ve had a serious allergic reaction to Topamax, your doctor may recommend taking a different medication instead.

Most Topamax side effects aren’t permanent and go away with time. For example, fatigue 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 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 your body makes). If left untreated, some side effects can cause long-term effects, such as increased pressure in your eye. Make sure to call your doctor right away if you have severe or bothersome symptoms.

If you have side effects that won’t go away or are hard to deal with, your doctor will likely have you wean off 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.

How long does Topamax stay in your system?

How long Topamax lasts in your system can depend on certain factors. For example, Topamax may last longer in the bodies of older adults and people with liver or kidney problems. This is because the liver and kidneys process Topamax.

Typically, a person’s body clears Topamax after 4 to 5 days. If your liver or kidneys don’t work as well as expected, your body may have difficulty removing Topamax. In addition, older adults (adults ages 65 years or older) may be more likely to have a liver or kidney problem than younger adults.

Before you start treatment with this drug, tell your doctor if you have a liver or kidney problem. If the problem is severe, your doctor may prescribe you a lower dosage of Topamax. For more details about Topamax’s dosage, see this article.

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

It’s possible. In clinical trials, the frequency of certain side effects varied depending on which dose of Topamax a person took.

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 shouldn’t cause side effects.

However, missing doses may cause you to have symptoms of the condition you’re taking Topamax to treat. For example, missing Topamax doses could cause you to have a migraine headache. Additionally, missing too many doses of Topamax (or suddenly stopping the drug) may increase the risk of seizures.

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 trials 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.

The “More common side effects” section above lists the most common side effects for each of these uses. 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:

If you develop an eye problem during treatment with Topamax, you may notice symptoms such as:

  • 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

Call 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 visit an eye doctor.

In most cases, eye side effects go away if you stop taking the drug. However, 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 trials.

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, call 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.

Suicide prevention

If you know someone at immediate risk of self-harm, suicide, or hurting another person:

  • Ask the tough question: “Are you considering suicide?”
  • Listen to the person without judgment.
  • Call 911 or the local emergency number, or text TALK to 741741 to communicate with a trained crisis counselor.
  • Stay with the person until professional help arrives.
  • Try to remove any weapons, medications, or other potentially harmful objects if it’s safe to do so.

If you or someone you know is having thoughts of suicide, a prevention hotline can help. The 988 Suicide and Crisis Lifeline is available 24 hours a day at 988. During a crisis, people who are hard of hearing can use their preferred relay service or dial 711 then 988.

Find more links and local resources.

Weight loss

It’s possible to have weight loss from taking Topamax. This side effect was reasonably common in clinical trials. (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
  • 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 not to 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 trials 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 wean off Topamax and try a different treatment for your condition. However, you should not stop taking Topamax unless your doctor recommends this.

Changes in taste

You may have changes in your sense of taste as a result of taking Topamax. This can cause foods to taste different or bad. Or you may notice a metallic or unusual taste in your mouth.

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

What you can do

Call 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. However, you should not stop taking Topamax unless your doctor recommends this.

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, call 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

Also, children taking Topamax may experience decreased bone mineral density (BMD). BMD describes how strong the bones are. Having reduced BMD could indicate that you have weakened bones.

In addition, Topamax may affect a child’s weight and height. This is because the drug can cause reduced growth in children. In clinical trials, reduced growth was more commonly seen among children ages 6 to 9 years. If a child is taking Topamax, their doctor will monitor their growth.

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

Below is important information you should consider before taking Topamax.

Before taking Topamax, discuss your health history with your doctor. Topamax may not be right for you if you have certain medical conditions or other factors affecting your health. Be sure to talk with your doctor if any of the following apply to you:

For more information about taking Topamax during pregnancy and breastfeeding, see this article.

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. However, 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.
  • Cost: If you’d like to learn about Topamax and cost, see this article.
  • Drug comparison: To learn how Topamax compares with Botox for migraine prevention, read this article.
  • Dosage: For information about the dosage of Topamax, view this article.
  • Interactions: To find out about Topamax’s interactions, see this article.

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.