Topamax and weight loss

Why there's no standard weight-loss dose

There's no normal Topamax dose for weight loss, because Topamax alone isn't approved for it. Topamax is approved for epilepsy and for preventing migraines. Many people lose some weight on it, but it isn't FDA-approved for weight loss by itself, so no label lists a weight-loss dose.

If weight is the goal, the approved form of topiramate is Qsymia, which pairs it with phentermine at lower topiramate doses than are often used for seizures.

How much weight topiramate causes

Weight loss is listed as a common side effect on the Topamax label, and it's more likely at higher doses. Early studies of topiramate alone as an obesity treatment found modest loss, but side effects like tingling and trouble concentrating were a problem, and it wasn't developed as a weight-loss drug on its own. Combining a lower dose with phentermine became the approach that won approval.

Topamax vs Qsymia at a glance

The approved version: Qsymia

Qsymia pairs low-dose phentermine with extended-release topiramate. On its label, as of our last review:

The label also tells prescribers to reassess and stop gradually if weight loss isn't enough at the top dose. In trials, average loss at the top dose was roughly 9% to 11% in about a year.

What the Qsymia trials showed

Two main trials, called EQUIP and CONQUER, tested Qsymia for about a year in adults with obesity or overweight with weight-related conditions. People on the top dose lost roughly 9% to 11% of their weight on average, compared with about 1% to 2% on placebo. People on the recommended middle dose lost less.

For someone at 220 lb, 10% is 22 lb. That's meaningful, though smaller on average than the newer GLP-1 medicines: see the strongest weight-loss pills. Evidence grade: moderate, since many people dropped out of these trials before the end.

Pregnancy precautions to know

Topiramate can cause birth defects such as cleft lip and palate. Qsymia is only dispensed through a safety program that includes pregnancy testing before starting and monthly, and effective birth control for people who can become pregnant. More: weight-loss medicines, pregnancy and birth control.

If you become pregnant while taking Qsymia or Topamax, the labels say to contact your prescriber right away. Don't stop Topamax on your own if you take it for seizures, since stopping suddenly can be risky too.

Side effects to know

• Tingling in hands and feet, and changes in taste.
• Trouble concentrating or finding words.
• Mood changes and trouble sleeping.
• Kidney stones and, rarely, sudden eye problems.
• A rise in blood acid levels (metabolic acidosis), which blood tests can check.
• With Qsymia, a faster heart rate from the phentermine.

Who should be careful

• People who are pregnant or could become pregnant without reliable birth control.
• People with glaucoma or an overactive thyroid, who shouldn't take Qsymia under its label.
• Anyone who took an MAOI antidepressant in the last 14 days.
• People with a history of kidney stones, heart disease or depression.

Topiramate shouldn't be stopped suddenly, because that can trigger seizures in some people. The Qsymia label also calls for stopping gradually. Your prescriber will plan this with you. If you'd like to compare other options, see every approved weight-loss medicine or check your BMI with the BMI calculator.

Questions to ask your prescriber

• Is Qsymia, a GLP-1 or another option the best fit for my health history?
• What birth control do I need, and how will pregnancy testing work?
• How will we check whether it's working, and when?
• Which side effects, like tingling, mood changes or eye pain, should I report right away?

When to talk to your doctor

• Before using topiramate for weight in any form.
• If you could become pregnant.
• If you notice eye pain or sudden vision changes (get care right away).
• If you have mood changes or thoughts of self-harm.