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Qsymia

Qsymia results: what the trials found

Average weight loss over 56 weeks, and what happened at two years

Last reviewed: September 2026

In the CONQUER trial, 2,487 adults taking Qsymia at the full 15/92 mg dose lost an average of 9.8% of their starting body weight over 56 weeks, compared with 1.2% on placebo. About 70% of participants lost at least 5% of their weight. Across the approved doses, average weight loss in trials ranges from about 7.8% to 9.8%. A 9.8% average is roughly 20 lbs at a 200 lb starting weight, or 25 lbs at 250 lbs.

What the trials measured

Qsymia has two published trials behind the figures used on this site — a 56-week trial and its two-year extension.

CONQUER
The Lancet, 2011
Who took part:
2,487 adults with obesity and at least two weight-related health conditions
How long:
56 weeks
Compared with:
Placebo
Average weight loss:
9.8% at the full 15/92 mg dose (placebo 1.2%)
Lost at least 5%:
70% of participants
Also measured:
Blood pressure, blood fats and blood sugar all improved
SEQUEL — the two-year extension of CONQUER
American Journal of Clinical Nutrition, 2012
Who took part:
People who completed the CONQUER trial
How long:
108 weeks in total
What it found:
Weight loss was sustained with continued health improvements at two years
Worth knowing:
The extension reports durability of the effect rather than a new weight loss percentage

What the averages look like in pounds

Averages from trial data. Individual results vary, but these give you a realistic picture of what to expect.

Weight loss milestones by percentage of starting body weight and by pounds lost, for two reference starting weights
Time% of body weight200 lb person250 lb person
56 weeks, 15/92 mg9.8% average~20 lbs~25 lbs
56 weeks, across approved doses7.8%–9.8%~16–20 lbs~20–25 lbs
Trial averages converted at starting weights of 200 lb and 250 lb, rounded to the nearest pound. CONQUER reports weight loss at 56 weeks, not month by month.

The four phases of the year

Knowing where you are in the arc helps you manage expectations — and stops you from panicking when the scale stalls.

1
Week 1

Appetite suppression starts

  • Appetite suppression typically begins within the first week
  • The starting dose is 3.75 mg phentermine / 23 mg topiramate once daily
2
Weeks 2–14

Titration to the full dose

  • The dose is titrated up towards 15/92 mg over about 14 weeks
  • Tingling in the hands and feet was reported by about 1 in 5 participants at the full dose
  • Your prescriber decides whether to keep increasing based on how you are responding
3
Weeks 12–16

Significant weight loss

  • Significant weight loss is typically seen by 12–16 weeks
  • CONQUER measured its headline result at 56 weeks, not at this point
  • About 7 in 10 participants had lost at least 5% by the end of the trial
4
Year 1–2

The two-year picture

  • In SEQUEL, weight loss was sustained through 108 weeks on continued treatment
  • Blood pressure, blood fat and blood sugar improvements continued alongside it
  • Weight regain after stopping is expected; no large dedicated withdrawal study has been published

The first month: managing expectations

Fast onset, slow titration

Unlike the GLP-1 drugs, appetite suppression on Qsymia typically begins within the first week. What takes time is the titration: the dose steps up from 3.75/23 mg towards 15/92 mg over roughly 14 weeks.

Significant weight loss is typically seen by 12–16 weeks. The 9.8% average from CONQUER was measured at 56 weeks on the full dose, so early-month numbers will be smaller than the headline figure.

Stopping and the two-year data

The effect held at two years on continued treatment

In SEQUEL, the two-year extension of CONQUER, people who stayed on treatment kept the weight off and continued to see health improvements. Weight regain after stopping is expected, and no large dedicated withdrawal study has been published. The FDA label also says the 15/92 mg dose should be stopped gradually rather than abruptly, because of a risk of seizures on abrupt withdrawal — so this is a conversation to have with your prescriber.

Common questions

Written and maintained by one person · Built with agentic AI tools · Every number checked against the cited trial · Not medical advice

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Full Qsymia overview →All Qsymia clinical evidence →Qsymia side effects →What to expect week by week →Qsymia cost →What happens if you stop →

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