Week by week — from your first dose through the first year
Last reviewed: September 2026·Based on 1 clinical trial
Your dose schedule
1
3.75 mg / 23 mgWeeks 1–14
Starting dose, then titrated upward across roughly 14 weeks. Appetite suppression typically begins in the first week.
2
15 mg / 92 mgWeeks 15+
The full dose used for the headline result in CONQUER.
Maintenance
Key insight
Qsymia is unusual: the appetite effect arrives quickly but the dose takes about 14 weeks to reach its full level. Fast onset, slow titration.
Starting Qsymia — what to expect
Once a day
Qsymia is a once-daily extended-release capsule. Your prescriber will tell you when to take it — timing can matter, because insomnia is one of the reported side effects.
The appetite change comes fast
Appetite suppression typically begins within the first week. The weight loss itself still takes months.
Pregnancy testing is part of the routine
The FDA label recommends a negative pregnancy test before starting and monthly during treatment for anyone who can become pregnant, because of the risk of birth defects from topiramate.
Drink more than you think you need
Topiramate raises the risk of kidney stones, and staying well hydrated is one of the main ways to reduce that risk. Dry mouth was reported by about 1 in 5 trial participants.
What most people experience
The starting dose is 3.75 mg phentermine with 23 mg topiramate. Appetite suppression often shows up quickly, but the dose is stepped up over about 14 weeks before it reaches the level that produced the headline trial result.
Your journey — what typically happens month by month
Based on CONQUER trial data (56 weeks) and patient-reported outcomes. Average weight loss was 9.8% at 56 weeks. Individual experiences vary significantly.
Week 1
Appetite suppression starts
Appetite suppression typically begins within the first week. You are still on the lowest dose at this stage.
What to watch: How much you are actually eating. The appetite change can be abrupt enough that people skip meals without noticing.
Weeks 2–14
Titration to the full dose
The dose is titrated upward toward 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, along with dry mouth and constipation.
What to watch: Tingling, word-finding difficulty and sleep. All three are listed effects of the topiramate component and are worth reporting rather than tolerating quietly.
Weeks 12–16
Significant weight loss
Significant weight loss is typically seen by 12 to 16 weeks. CONQUER measured its headline result at 56 weeks, so the numbers at this stage are smaller than the trial average.
What to watch: Blood pressure. Phentermine raises heart rate, and monitoring is part of taking this drug.
Year 1–2
The two-year picture
In CONQUER, average weight loss at 56 weeks on the full dose was 9.8%, against 1.2% on placebo. In SEQUEL, the two-year extension, weight loss was sustained with continued health improvements at 108 weeks.
What to watch: The label says the 15/92 mg dose should be stopped gradually rather than abruptly, because of a risk of seizures on abrupt withdrawal. Never simply stop.
Key insight
Qsymia is the reverse of the GLP-1 pattern. The appetite effect shows up in week one, but the dose takes about 14 weeks to reach full strength and the headline trial result was measured at 56 weeks. Fast start, long road.
Tips for starting — what actually helps
Some tips apply to everyone on weight loss medication. Others are specific to Qsymia. Both matter most in the first 8 weeks.
Important
Keep the pregnancy testing schedule
The label recommends a negative test before starting and monthly during treatment for anyone who can become pregnant, alongside effective contraception. This is the single most important rule with this drug.
Qsymia-specific
Hydrate consistently
Kidney stones are a listed warning and dry mouth is one of the most common side effects. Water through the day helps with both.
General
Talk about timing if you cannot sleep
Insomnia was reported by about 1 in 10 participants and comes from the phentermine component. Your prescriber may adjust when you take it.
Important
Never stop it abruptly
The label warns about seizures on abrupt withdrawal and says the full dose should be stepped down under supervision.
Qsymia-specific
Be careful in the heat
Reduced sweating and overheating are listed warnings. Take heat and hard exercise seriously, especially in summer.
General
Eat even when you are not hungry
Appetite suppression arrives quickly with this drug. Skipping meals costs you muscle and energy — eat regularly whether or not hunger prompts you.
General
Protein at every meal
When appetite drops, what you eat has to work harder. Protein protects muscle during weight loss.
General
Weigh weekly, not daily
Day-to-day weight moves by several pounds on water alone. Track the trend across weeks instead.
What people actually say about starting
Personal experiences from public online communities — not medical advice.
“The brain fog side effect (topiramate) is real for some people — it can affect word-finding and short-term memory. Discuss with your doctor if this becomes an issue.”
r/phentermine
“Now that generic is available, cost is dramatically lower. Some pharmacies charge under $50/month.”
r/antiobesitymedication
“Drink plenty of water — topiramate increases kidney stone risk, and staying well hydrated is one of the main ways to reduce it.”
r/Qsymia
Bottom line
→Week 1: appetite suppression typically begins.
→Weeks 2–14: the dose is titrated toward 15/92 mg. Tingling, dry mouth and constipation are the common effects.
→Weeks 12–16: significant weight loss is typically seen by this point.
→Year 1–2: CONQUER found 9.8% average loss at 56 weeks; SEQUEL found it held at two years on continued treatment.
→Two rules that are not optional: monthly pregnancy testing if you can become pregnant, and never stopping the full dose abruptly.
Common questions
Appetite suppression typically begins within the first week. Significant weight loss is usually seen by 12 to 16 weeks, once the dose has been titrated up.
The dose is titrated from 3.75/23 mg up to 15/92 mg over about 14 weeks. Your prescriber decides whether to keep stepping up based on how you are responding and how well you tolerate it.
The FDA label states that topiramate exposure in the first trimester increases the risk of major congenital malformations, including cleft lip and cleft palate. It recommends a negative pregnancy test before starting and monthly during treatment for anyone who can become pregnant.
It is the most distinctive side effect of the topiramate component — about 1 in 5 participants at the full dose reported it, against 2% on placebo. The label reports that 1% of adults stopped Qsymia because of it. Tell your prescriber if it becomes uncomfortable.
In CONQUER, 2,487 adults on the full 15/92 mg dose lost an average of 9.8% of their starting body weight over 56 weeks, against 1.2% on placebo. About 70% lost at least 5% of their weight.
No. The label warns about a risk of seizures if the drug is withdrawn abruptly, and says the 15/92 mg dose should be stepped down gradually. Plan any stop with your prescriber.
Written and maintained by one person · Built with agentic AI tools · Every number checked against the cited trial · Not medical advice
Built with agentic AI tools and not a substitute for medical advice
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