Is it safe during pregnancy?

No — topiramate is a known teratogen (it causes birth defects, particularly cleft palate). Women who could become pregnant must use two forms of contraception while taking this drug. A monthly pregnancy test is required as part of the FDA REMS safety programme. Discuss this with your doctor.

What is "brain fog" and will it affect me?

Topiramate can cause word-finding difficulties and short-term memory problems in some people — informally called "Dopamax" fog in online communities. It is more common at higher doses and often improves or resolves at lower doses. Talk to your doctor if it affects your work or daily life.

Avoid alcohol while taking this drug. Topiramate increases the sedative effects of alcohol and can worsen cognitive side effects. The combination is not recommended.

How is this different from phentermine alone?

Phentermine alone is approved for short-term use only (12 weeks). Adding topiramate allows much longer-term use and produces more weight loss than either drug on its own. Generic phentermine is also available separately at a much lower cost, but for short-term use only.

What if I can't afford the brand version?

Generic phentermine/topiramate became available in 2025 — some pharmacies offer it under $50–$80/month, compared to ~$200–$400 for brand Qsymia. Ask your pharmacist.

Phentermine / Topiramate ER (Qsymia)

Key facts

At a glance

The numbers you need before deciding.

Weight loss

9.8%

~22 lbs for a 220 lb person

Monthly cost

$30–$400/mo

Generic version (available 2025): ~$30–$80/month

How you take it

Daily capsule

One capsule each morning

Main side effect

Tingling in hands/feet

About 2 in 10 people

Fat vs lean

Limited data

Body composition breakdown not yet published

If you stop

Weight regain expected

Pattern consistent with the drug class

Before you start

Learn about this treatment

Everything you'd want to know before deciding.

Weight loss results

Trial data, timelines, what's realistic

Side effects

Rates, what helps, and when to call your doctor

Cost & savings

List price, insurance, manufacturer programs

How it works & dosage

Combination oral — what that means for you

Clinical evidence

2 trials, all linked

On treatment

Already taking this?

Practical guides for people currently on this medication.

Dose titration schedule

Step-by-step dose increases

Not losing weight yet?

Troubleshooting — what to check first

Nausea or GI issues

What helps right now — from trial data

Missed a dose

When to take it, when to skip

What to eat

Protein targets, meal timing, appetite shifts

Week-by-week journey

What to expect from week 1 to month 12

Clinical evidence

How it compares in trials

Average weight loss % — from individual phase 3 trials

Phentermine / Topiramate

9.8%

Semaglutide injection

14.9%

Tirzepatide

20.9%

Affordability

Cost & savings

$30–$400per month

Savings options

Generic version (available 2025): ~$30–$80/month. Brand Qsymia: ~$150–$400/month.

Is this right for you?

Who this tends to fit

Relevant if you

Prefer a daily pill and want to avoid injections
Want one of the most affordable prescription options
Are comfortable with its side effect profile

Not right if you

You are pregnant or could become pregnant (causes birth defects)
You have glaucoma or hyperthyroidism
You have a history of kidney stones
You want to avoid a controlled substance

Safety

Important cautions

Do not take this drug if you are pregnant or could become pregnant — topiramate causes serious birth defects (cleft palate). Two forms of contraception are required. A monthly pregnancy test is part of the FDA safety programme.
This drug can increase heart rate. Your doctor should monitor pulse at each visit.
Topiramate can cause metabolic acidosis (a build-up of acid in the blood) and kidney stones with prolonged use.

Practical guide

How to take Phentermine / Topiramate ER

Take one capsule every morning — do not take in the afternoon or evening (may cause insomnia)

Swallow the capsule whole — do not crush, chew, or break it

Your doctor may increase your dose after 12 weeks if needed

Do not stop suddenly — taper the dose gradually under medical supervision

Common questions

FAQ

Medical disclaimer: This website is for informational purposes only and does not constitute medical advice. Always consult a qualified healthcare provider before starting, stopping, or changing any treatment.