Dosing and Side Effects of Topamax for Migraine Prevention

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Topamax (topiramate) is an anti-seizure medication approved by the FDA for the prevention of migraines. When prescribed, Topamax is given in a tapered fashion, meaning the amount is slowly increased until a person is on a therapeutic dose.

Let's learn more about how and why Topamax is given in a tapered fashion, and also what to watch out for when taking it. 

How is Topamax Dosed?

Topamax is available in 25mg, 50mg, 100mg, and 200mg tablets.

It's also available in 15mg and 25mg capsules. Topamax is commonly dosed by safely tapering up the dose to a therapeutic level, which is 100mg or 200mg daily. For example, a neurologist may start a patient at 25mg once daily for a week and then increase the dose by 25mg every week, until the person is taking 100mg or 200mg daily. This minimizes side effects while maximizing the medication benefit. 

Likewise, if a person is stopping Topamax, tapering the dose down is also recommended. 

What are the Potential Side Effects of Topamax?

One serious side effect of Topamax is a syndrome of acute myopia associated with secondary angle closure glaucoma. Symptoms include a sudden onset of vision and/or eyeball pain. These symptoms, if they occur, usually start within one month of starting Topamax, and can occur in children, as well as in adults. Treatment of this eye syndrome is to stop Topamax as quickly as possible, with the judgment and monitoring of the doctor who prescribed it.

Another serious side effect is the elevation of a person's body temperature due to decreased sweating. This is more common in children taking Topamax.

Topamax can also cause a condition called metabolic acidosis, which usually occurs early in the course of therapy. It's caused by an imbalance of bicarbonate in the body.

This may cause kidney stones, so patients are generally advised by their doctors to drink an adequate amount of fluids while on Topamax. Also, like other anti-seizure medications, Topamax may increase a person's risk for suicidal thoughts and behavior. It's important that a person seek medical attention right away if they notice a change in their mood or behavior, and call 911 in an emergency.

Side Effects of Topamax that are Dose-Dependent

In adults, Topamax has been linked to causing some cognitive disturbances like word-finding difficulties and difficulty with memory and attention. It may also cause some fatigue, drowsiness, or mood problems, like depression.

These symptoms usually begin during the titration phase — when the medication is being slowly increased and are dose-dependent, meaning their likelihood is higher with higher doses of Topamax. Other possible side effects include dizziness, nausea, numbness and tingling, loss of appetite, insomnia, weight loss, and diarrhea

What Does This Mean for Me?

If you are prescribed Topamax, it's important to not stop taking it or change the dosage without first consulting your doctor.

In particular, Topamax should not be stopped abruptly, unless there is an urgent need, under the guidance of your doctor. 

For many people, Topamax is an effective preventive medication — but please take it correctly, safely, and under the care of your doctor. If you experience any side effects, especially blurry vision or eyeball pain, report these to your physician as soon as possible.

Sources:

FDA. Medication Guide: Topamax.

Silberstein SD, Neto W, Schmitt J, Jacobs D & MIGR-001 Study Group. Topiramate in migraine prevention: results of a large controlled trial. Arch Neurol. 2004 Apr;61(4):490-5.

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