At a glance
| Saxenda | Qsymia | |
|---|---|---|
| Form | Daily injection | Daily capsule |
| How often | Daily injection | Daily oral capsule — no injection |
| Weight loss in trials | Up to 8% — SCALE Obesity and Prediabetes (56 weeks) | Up to 9.8% — CONQUER (56 weeks) |
| FDA approved | 2014 | 2012 |
| Made by | Novo Nordisk | Vivus |
| How it works | A GLP-1 analogue with a half-life of approximately 13 hours (requiring daily injection). | Phentermine suppresses appetite by triggering the release of adrenaline-like chemicals in the brain's hunger control centre. |
| Monthly cost, self-pay | $1,000–$1,349/mo | $30–$400/mogeneric; brand runs to $400 |
| Most reported reaction | Nausea 40% (SCALE Obesity and Prediabetes) | Dry mouth 21% (CONQUER) |
Every figure in this table is read from the same trial and label records used everywhere else on this site.
Weight loss in each drug's main trial
No head-to-head trial has compared these two drugs.
SCALE Obesity and Prediabetes (56 weeks)
CONQUER (56 weeks)
In clinical trials, participants taking liraglutide lost on average up to 8% of their starting body weight, and participants taking phentermine / topiramate ER lost on average up to 9.8%. Those numbers come from two different studies: SCALE Obesity and Prediabetes enrolled 3,731 adults with obesity or overweight with comorbidities over 56 weeks against placebo, while CONQUER enrolled 2,487 adults with obesity and at least 2 weight-related health conditions over 56 weeks against placebo. Who took part, how long each trial ran and what each drug was measured against all move the percentage, so the two figures are not a measured difference between the drugs.
Monthly cost, self-pay
The bar spans the range in each drug's price record — lowest listed price to highest.
Brand (Saxenda) ~$1,000–$1,349/month. Generic liraglutide is typically $135–$200 less than brand.
generic; brand runs to $400
~$30–$80/month generic; ~$200–$400/month brand (Qsymia).
Self-pay prices are what the manufacturer or the pharmacy lists, not what most people end up paying. Saxenda: $1,000–$1,349/month. Qsymia: $30–$400/month. Insurance, dose and pharmacy all change both figures.
Side effects reported in the trials
Both trials reported one reaction in common. Each rate is the percentage of participants who reported it in the trial named beside it, so the two columns are not from the same study.
A rate is the share of trial participants who reported that reaction, not a prediction for any one person.
How they differ in practice
How you take it
- Saxenda — Once-daily subcutaneous injection
- Qsymia — Once-daily extended-release capsule
Dose build-up
- Saxenda — 0.6 mg → 3.0 mg, escalated over 4 weeks
- Qsymia — 3.75/23 mg → 15/92 mg, titrated over 14 weeks
Where a drug is not listed here, its prescribing information sets out its own dose steps.
How soon it acts
- Saxenda — Effects visible within 4–8 weeks; maximum benefit typically by 56 weeks
- Qsymia — Appetite suppression typically begins within the first week; significant weight loss by 12–16 weeks
Heart and metabolic findings
- Saxenda — The LEADER trial (type 2 diabetes) showed cardiovascular benefit.
- Qsymia — In CONQUER, significant reductions in blood pressure, waist circumference, triglycerides, and blood glucose were observed.
As stated in each drug’s trial record — not a claim about which drug protects the heart more.
Other findings recorded
- Saxenda — Approved for adolescents aged 12 and over (SCALE teens programme); generic liraglutide now available (Teva, August 2025) — reducing out-of-pocket cost
- Qsymia — Generic now available (from 2025) — significantly lower cost than GLP-1 drugs; improved blood pressure and triglycerides in CONQUER trial
If you stop taking it
- Saxenda — Weight regain after stopping is expected, as with other GLP-1 drugs.
- Qsymia — Weight regain after stopping is expected.
Common questions
Written and maintained by one person · Built with agentic AI tools · Every number checked against the cited trial · Not medical advice
Clinical evidence — Liraglutide and Phentermine / Topiramate ER
No head-to-head trial has compared these two drugs.
- SCALE Obesity and Prediabetes — Liraglutide: 3,731 adults with obesity or overweight with comorbidities, 56 weeks. New England Journal of Medicine, 2015. View source ↗
- CONQUER — Phentermine / Topiramate: 2,487 adults with obesity and at least 2 weight-related health conditions, 56 weeks. The Lancet, 2011. View source ↗
- Saxenda (liraglutide) — FDA prescribing information — DailyMed View source ↗
- Qsymia (phentermine and topiramate extended-release) — FDA prescribing information — DailyMed View source ↗
Next step most people take
Built with agentic AI tools and not a substitute for medical advice
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