How long before Qsymia starts working?

Two different things get called "working". Appetite changes are commonly reported within the first weeks, at doses the label describes as initiation rather than treatment. The weight-loss figure people quote is measured over a full trial at the maintenance dose, which this label does not reach before week 3. A page that answers with one number is answering only one of the two questions.

How much weight can you lose on Qsymia in 3 months?

No average for Qsymia at three months is printed in its label or in FDA's review of it; the early weeks appear there only as a graph. The earliest printed figures: week 28, −8.2% (about 19 lb) on 7.5 mg/46 mg in OB-301, counting everyone randomized; week 28, −9.0% (about 20 lb) on 15 mg/92 mg in the same trial. Each is an average, and each counts a different group of people.

Can the schedule be moved faster?

That is a prescriber's decision and this page does not advise on it. What the label says is the escalation interval it was studied at; going faster is off-label territory and going slower is common where side effects are hard. The reactions the label lists — tingling in the hands and feet, dizziness, altered taste, insomnia — are typically worst just after a step up.

Do I pay for the titration months?

Yes, every one of them. Qsymia is $75 a month at maintenance on this site. The months before maintenance are not free trial months; they are billed at the price for that dose.

← Qsymia (phentermine/topiramate)

How long does Qsymia take to work?

Earliest week the maintenance dose is reachable

Week 3

2 weeks of dose escalation at one starting dose before the maintenance dose — quoted from the label, not estimated.

No clinician has reviewed this page. Label and trial statements are quoted from the FDA label or the trial cited beside them. General guidance is marked as such, and every price carries the date it was verified. That is sourcing, not medical review. What we do and do not check · Who checked the price

Last updated 2026-04-24 — the version of the FDA label this schedule comes from. Read and dated by Alex Seot.

How long does it take for Qsymia to work?

Qsymia reaches its maintenance dose no earlier than week 3, because the FDA label steps the dose up on a schedule rather than starting at the maintenance dose. That is 2 weeks of titration at one starting dose before the maintenance dose, and it is the reason an advertised first-month price says so little. The figure people usually ask about comes from CONQUER, Study 2 on the label, 56 weeks: 9.8% mean weight loss at the 15 mg/92 mg dose against 1.2% on placebo, intention-to-treat. Appetite changes are usually reported within the first weeks, but the trial figure is measured over its full length rather than at any earlier point — the two are different claims and are often quoted as one. Every week of that schedule is billed: $75 a month at maintenance on this site, with its source and the date it was read on its price page.

The schedule, week by week — and what each week costs

Doses and intervals are quoted from FDA prescribing information for Qsymia (phentermine/topiramate). Prices are the published figure for that dose where the manufacturer prices per step; where it charges one price throughout, the column says so.

When	Dose	A month at this step	What the label notes
Days 1–14	3.75 mg / 23 mg	$75 — one price throughout	Initiation.
Day 15 and on	7.5 mg / 46 mg	$75 — one price throughout	The usual dose. After 12 weeks at this dose (about week 14 of treatment), an adult who has not lost at least 3% of body weight — or a patient aged 12 to 17 whose BMI has not fallen 3% — moves to 11.25/69 for 14 days, then 15/92.
Higher steps	11.25 mg / 69 mg then 15 mg / 92 mg	$75 — one price throughout	Only if the response at 7.5 mg/46 mg is insufficient. Moderate or severe kidney impairment (creatinine clearance under 50 mL/min) or moderate liver impairment (Child-Pugh 7 to 9) caps the dose at 7.5 mg/46 mg; mild impairment of either changes nothing. With kidney failure on dialysis, or severe liver impairment (Child-Pugh 10 to 15), the label says to avoid Qsymia altogether.

What “working” is being measured

The number quoted everywhere for Qsymia is 9.8% mean weight loss, and it comes from CONQUER, Study 2 on the label, 56 weeks: 9.8% mean weight loss at the 15 mg/92 mg dose against 1.2% on placebo, intention-to-treat. That figure is the endpoint of a trial, not a milestone you pass on a particular week — and it is an average across everyone in the trial, so individual results sit on both sides of it.

Appetite change is the thing most people notice first and it is commonly reported in the early weeks — at doses the label itself calls initiation rather than treatment. Conflating that with the trial figure is how “it works in a week” gets written.

The reactions the label lists in at least 5% of patients — tingling in the hands and feet, dizziness, altered taste, insomnia, constipation — cluster just after a step up rather than at a steady dose. The full label list →

How much weight by month 3 or 6?

The trials draw their early weeks as a graph, and this site does not read numbers off a graph. These are the earliest figures printed as text or in a table, each with who was counted — which moves the number more than the week does.

When	Average change	In pounds	Who was counted
Week 28about 6 months	−8.2%placebo −1.5%	about 19 lb	Everyone randomized to 7.5 mg/46 mg in OB-301, a 28-week trial, a missing weight carried forward from the last visit. FDA medical review of Qsymia (NDA 22580), OB-301 week-28 table
Week 28about 6 months	−9.0%placebo −1.5%	about 20 lb	Everyone randomized to 15 mg/92 mg in the same trial. FDA medical review of Qsymia (NDA 22580), OB-301 week-28 table

Pounds are the source's own kilograms converted, or its percentage applied to the average starting weight of the people it counted. Someone who starts lighter loses fewer pounds at the same percentage.

Full dosing chart →Qsymia cost without insurance →What a year actually costs →Qsymia price and sources →

Everything on Qsymia

Qsymia timeline, answered

How long before Qsymia starts working?: Two different things get called "working". Appetite changes are commonly reported within the first weeks, at doses the label describes as initiation rather than treatment. The weight-loss figure people quote is measured over a full trial at the maintenance dose, which this label does not reach before week 3. A page that answers with one number is answering only one of the two questions.
How much weight can you lose on Qsymia in 3 months?: No average for Qsymia at three months is printed in its label or in FDA's review of it; the early weeks appear there only as a graph. The earliest printed figures: week 28, −8.2% (about 19 lb) on 7.5 mg/46 mg in OB-301, counting everyone randomized; week 28, −9.0% (about 20 lb) on 15 mg/92 mg in the same trial. Each is an average, and each counts a different group of people.
Can the schedule be moved faster?: That is a prescriber's decision and this page does not advise on it. What the label says is the escalation interval it was studied at; going faster is off-label territory and going slower is common where side effects are hard. The reactions the label lists — tingling in the hands and feet, dizziness, altered taste, insomnia — are typically worst just after a step up.
Do I pay for the titration months?: Yes, every one of them. Qsymia is $75 a month at maintenance on this site. The months before maintenance are not free trial months; they are billed at the price for that dose.

The schedule is quoted from FDA prescribing information for Qsymia (phentermine/topiramate), read directly. This page reports what the label says and does not recommend a dose or a schedule; that is a conversation with a prescriber. Information only, not medical advice.