Key takeaways

Topamax (topiramate) is widely used as a preventive medication for migraines in the United States, initially approved for this purpose in adults in 2004, despite originally being an antiepileptic drug.
The mechanism by which Topamax works to alleviate migraine symptoms remains unclear, with its effects on sodium and calcium channels and various nerve receptors suspected to be involved.
Common side effects of Topamax include tingling sensations, loss of appetite, sleepiness, nausea, and brain fog, with tolerability varying significantly among individuals.
Topamax may be beneficial for individuals experiencing at least four severe migraine days per month, but it is not suitable for everyone, especially during pregnancy or for those with a history of calcium-based kidney stones.

As if having frequent migraines isn’t painful enough, figuring out which medication—or combination of medications—is right for you can be a major challenge. Thankfully, several therapeutic options exist for both preventing and relieving pain. That’s good news for the 38 million Americans who live with migraine.

One of those options, Topamax (topiramate), is widely prescribed as a preventive migraine medication, despite its original use as an antiepileptic drug for people with a history of seizures.

In fact, topiramate is actually the most commonly prescribed oral preventative medication for migraines in the United States—having been approved for migraine treatment in adults in 2004, according to Deborah I. Friedman, MD, professor of neurology at University of Texas Southwestern Medical Center and a member of the American Headache Society.

How does Topamax work for migraines?

Actually, that piece of the puzzle is still unknown.

“Topiramate works via different mechanisms, and it’s not clear which one is important for migraine,” Dr. Friedman says, explaining that topiramate works along sodium and calcium channels in the body, as well as on different receptors where nerves send signals.

As far as the discovery that topiramate could improve migraine symptoms, it was largely accidental. Friedman says epilepsy patients reported an improvement in their migraine symptoms while taking topiramate and other similar drugs.

How much Topamax should I take for migraines?

The dosage of Topamax for migraines is usually less than it is for epilepsy, with most doctors starting low and increasing the amount gradually over time, according to Danny Park, MD, section head of neurology at Swedish Covenant Hospital in Chicago.

“Typical dosing starts with 25 milligram tablets twice daily,” he says. “To mitigate adverse effects, I typically increase by 25 milligrams daily every week…[with the] maximum dose being around 100 milligrams twice daily.”

What are the most common side effects of Topamax for migraines?

Though Topamax can be successful in reducing the frequency and severity of migraines, that success often comes at a price—many people struggle to tolerate the common side effects of the drug, which Dr. Friedman says may include:

a tingling, pins-and-needles sensation in the extremities or face
loss of appetite leading to weight loss
sleepiness/drowsiness
nausea
brain fog

Dr. Park adds that these side effects can be experienced across the range of dosages for topiramate depending on the individual patient.

“I have some patients who get to 100 milligrams twice daily [without side effects] and unfortunately some patients who do not tolerate even 25 milligrams daily,” he says.

Could Topamax work for you?

You don’t have to be a chronic migraine sufferer (i.e., someone who has 15 or more migraine days per month, according to the American Migraine Foundation) to benefit from a preventive medication like Topamax. But Dr. Friedman says the patients who respond to the drug usually have a few other things in common.

“We think about migraine prevention therapies in people who have at least four headache days per month with severe disability from migraines,” she says, meaning that your migraines prevent you from performing your usual daily tasks.

Also included are people who have inadequate relief from acute therapies for migraine and those who have special kinds of migraine (like hemiplegic or brainstem aura) regardless of the frequency.

However, topiramate is not suitable for everyone. Friedman says it cannot be taken during pregnancy, and that she would “think twice” about prescribing it to someone with a history of calcium-based kidney stones because some research indicates topiramate can increase the risk of developing them.

Benefits of taking Topamax

It may take a while for you to feel the full benefit of Topamax for migraines—Dr. Friedman says lots of people see improvement in the first month, but it can continue improving for the first year. She also says that past clinical trials have shown 50% of people feeling 50% better on topiramate, with some reporting an even higher response rate.

But side effects are topiramate’s biggest downside; some people simply can’t tolerate them.

“It’s a ‘love it or hate it’ drug,” says Dr. Friedman, “and sometimes people are afraid to take it because they hear about the side effects. But not everyone gets them, so it’s important to be open-minded about it.”