Topamax Side Effects

Doctors prescribe Topamax (topiramate) for epileptic seizures and migraines because it works to decrease abnormal nerve cell activity. They also frequently prescribe it with other medications to treat Lennox-Gastaut syndrome, a form of childhood-onset epilepsy that causes seizures and developmental delays.

The list of warnings and precautions in the medication guide is extensive, and the drug’s maker has continually updated the safety information since the medicine became available in the United States. The Food and Drug Administration mandated the updates over the years as postmarketing studies continued to confirm the potential for adverse health effects.

People with seizure disorders usually take larger doses of Topamax than do people with migraines, and the list of common side effects is more extensive for this group of patients.

The most common side effects among people taking the drug for migraine include burning or prickling sensations, loss of appetite, weight loss, difficulty with memory, diarrhea, nausea, abdominal pain, infection, and changes in the way things taste. Some users say that carbonated drinks, in particular, taste bad or “flat” when they are on the drug.

The drug’s prescribing information advises doctors to warn patients about the potential for extreme tiredness, dizziness, confusion, difficulty concentrating or visual effects. Patients should not drive or operate machinery until they can determine whether the drug adversely affects their mental performance, motor performance and/or vision.

The medication label also warns of more serious side effects that may occur, including vision problems, suicidal behavior and birth defects.

Quitting Topamax suddenly can also bring on seizures. As a result, people should gradually taper off the drug or be closely monitored if they must stop taking it abruptly, according to the drug’s label.

Infants exposed to topiramate in utero have an increased risk for cleft lip and/or cleft palate, especially if the drug is taken during the first trimester of pregnancy, and for being smaller than the usual weight for the number of weeks of pregnancy. The drug’s label advises doctors to consider the risks and benefits of prescribing the drug to women who can become pregnant.

Surveillance data from the North American Antiepileptic Drug (NAAED) Pregnancy Registry showed 1.4 percent of babies born to women taking Topamax had oral clefts, compared to a prevalence of 0.38 to 0.55 percent in infants whose mothers took other anticonvulsant medications and 0.07 percent in infants of mothers without epilepsy or those mothers not taking other anticonvulsant medications.

Additionally, a 2008 study in Neurology journal looked at the UK Epilepsy and Pregnancy Register and found babies born to mothers who took Topamax during pregnancy suffered birth defects at 11 times the average rate.

In March 2011, the FDA issued a warning that Topamax may increase the risk of oral cleft birth defects as much as 21.3 percent based on data from the NAAED pregnancy registry. The Topamax product labeling states that the drug can cause fetal harm when administered to a pregnant woman.

“Cleft lip and cleft palate range from a small notch in the lip to a groove that runs into the roof of the mouth and nose, possibly leading to problems with eating, talking and ear infections,” according to the FDA. “Surgery is often used to close the lip and palate.”

Following the 2011 safety alert, people began filing Topamax lawsuits claiming the manufacturer should have fully informed women of the risk of birth defects but failed to do so despite evidence of increased birth defects available as early as 2008.

Birth Control, Pregnancy and Breastfeeding

The FDA advises women of childbearing age who decide to take Topamax and who do not plan to become pregnant to use effective birth control. The medication may make certain birth control pills less effective, so it is crucial that women who can become pregnant and their doctors know the risks and discuss options. Women should ask their doctors about the best kind of birth control to use while taking the drug.

Women who become pregnant or who plan to become pregnant should talk to their doctors immediately about whether it’s appropriate to continue taking topiramate. Even if women become pregnant, they should not stop taking the drug unless a doctor instructs them to do so. Discontinuing the medication suddenly can cause serious problems.

It’s important to know that topiramate passes into breast milk; diarrhea and sleepiness have been seen in breastfed infants whose mothers take the drug. Women who are currently breastfeeding should consult their doctor about the best method for feeding an infant while using this medication.

Topamax can lead to serious eye disorders called acute myopia and secondary angle closure glaucoma. Both conditions can cause permanent blindness if left untreated.

Acute myopia is the medical term for very nearsightedness, a vision condition in which people can see nearby objects clearly, but objects at a distance appear blurred.

Secondary angle closure glaucoma happens when the angle between the iris and cornea begins closing. The condition develops very quickly and has been reported in children and adults.

Even low doses of topiramate can cause angle closure glaucoma, acute myopia and other eye problems. A 2010 case report in the Oman Journal of Ophthalmology described a 23-year-old who developed the disorders while taking just 25 mg daily. Typical doses are usually in the range of 50 mg to 400 mg per day.

Symptoms of these eye disorders typically occur within one month of starting Topamax. People taking the drug should seek immediate medical attention if they experience blurred vision, visual disturbances or pain around the eyes.

The main treatment to reverse symptoms of myopia and secondary angle closure glaucoma is to stop taking the medicine as soon as possible. However, do not stop taking the drug without consulting your doctor. A doctor may also provide medications to lower fluid production or increase its outflow.

Partial vision loss unrelated to eye pressure has also been reported in clinical trials and in postmarketing experience in people taking topiramate. Most of these visual field defects went away after the patient stopped using the drug.

The drug’s label advises doctors and their patients to consider discontinuing the medication if visual problems occur at any time during treatment.

In 2019, doctors wrote more than 10 million prescriptions for topiramate. Increased on- and off-label Topamax use increases the number of people at risk of eye problems, according to an August 2022 article. Study authors recommend ophthalmologists conduct testing for Topamax side effects and start treatment as soon as possible to avoid permanent blindness.

Topamax can increase the risk of suicidal thoughts or behavior. People who take the drug should be monitored for signs of new or worsening depression, increased anxiety or panic, and/or any unusual changes in mood or behavior.

In 2008, the FDA completed a pooled analysis of nearly 200 medical studies that showed antiepileptic drugs cause an increase in suicidal thoughts and behaviors. Based on the outcome of this review, the FDA required all manufacturers of drugs in this class to include a warning in their labeling and develop a medication guide for patients to inform them of the risks of suicidal thoughts and behaviors.

The FDA’s pooled analyses involved 199 placebo-controlled clinical trials of 11 different antiepileptic drugs (AEDs). It showed that patients taking AEDs had about twice the risk of suicidal thinking or behavior compared to patients taking a placebo.

Patients in these trials took the drugs for a median duration of 12 weeks. In that time, the estimated incidence rate of suicidal thoughts or behavior among 27,863 AED-treated patients was 0.43 percent, compared to 0.24 percent among 16,029 placebo-treated patients. The analysis found an increase of about one case of suicidal thinking or behavior for every 530 patients treated.

“The increased risk of suicidal thoughts or behavior with AEDs was observed as early as one week after starting drug treatment with AEDs and persisted for the duration of treatment assessed,” according to the Topamax prescribing information. “Because most trials included in the analysis did not extend beyond 24 weeks, the risk of suicidal thoughts or behavior beyond 24 weeks could not be assessed.”