Different Worlds: Class Comparison
Before comparing specific drugs, it's worth anchoring the comparison at the drug-class level. The anti-obesity drugs available in 2026 fall into four distinct classes, each with a different mechanism:
Stimulant + Anticonvulsant
Phentermine — a sympathomimetic amine chemically related to amphetamine — combined with topiramate, an anti-seizure medication originally used in epilepsy.
- DEA Schedule IV controlled substance
- Suppresses appetite via CNS stimulation
- Topiramate mechanism in weight loss is incompletely understood
- REMS program required
Incretin Hormone Mimic
Semaglutide, tirzepatide, and liraglutide are synthetic analogs of GLP-1 — a gut hormone your body already makes. They regulate appetite, satiety, and glucose.
- Not a controlled substance
- Slows gastric emptying, increases satiety
- Endocrine mechanism — well-characterized
- No REMS enrollment required
The full class map in one table:
| Class | Mechanism | Examples | Controlled? |
|---|---|---|---|
| Sympathomimetic + anticonvulsant combo | CNS stimulation + appetite-reward suppression | Qsymia | Yes (Sch IV) |
| Sympathomimetic alone | CNS stimulation, norepinephrine release | Phentermine (Adipex-P, Lomaira) | Yes (Sch IV) |
| Opioid antagonist + antidepressant combo | Reward-pathway modulation | Contrave | No |
| GLP-1 receptor agonist | Mimics gut hormone; slows gastric emptying, raises satiety | Wegovy, Saxenda, Ozempic, Rybelsus | No |
| Dual GIP/GLP-1 agonist | Both GIP and GLP-1 receptors | Zepbound, Mounjaro | No |
| Lipase inhibitor | Blocks dietary fat absorption | Orlistat (Xenical, Alli) | No |
Efficacy Head-to-Head
All numbers below are from the pivotal FDA registration trial for each drug, reported at each drug's primary efficacy endpoint. This is cross-trial comparison (different populations, different trial durations), not head-to-head, but the patterns are consistent enough to be informative.
| Drug | Dose | Duration | Mean weight loss | % reaching ≥10% |
|---|---|---|---|---|
| Zepbound (tirzepatide) | 15 mg weekly | 72 weeks | 20.9% | 83% |
| Zepbound (tirzepatide) | 10 mg weekly | 72 weeks | 19.5% | 78% |
| Wegovy (semaglutide) | 2.4 mg weekly | 68 weeks | 14.9% | 69% |
| Qsymia | 15 / 92 daily | 56 weeks | 9.8% | 48% |
| Qsymia | 7.5 / 46 daily | 56 weeks | 7.8% | 37% |
| Saxenda (liraglutide) | 3 mg daily | 56 weeks | 7.4% | 33% |
| Contrave | 32/360 daily | 56 weeks | 6.1% | 31% |
| Phentermine alone | 15–37.5 mg daily | 12–24 weeks | ~5% | Limited data |
| Orlistat | 120 mg tid | 52 weeks | 3.1% | 14% |
Sources: FDA registration trials — SURMOUNT-1 (Zepbound), STEP 1 (Wegovy), CONQUER/EQUIP (Qsymia), SCALE (Saxenda), COR-I (Contrave), pivotal phentermine trials, XENDOS (orlistat). Percentages are placebo-subtracted and reflect intent-to-treat analysis.
Two patterns are visible:
- GLP-1 family dominates efficacy. Zepbound and Wegovy produce the highest mean weight loss by a meaningful margin (roughly 1.5–2× Qsymia's maximum).
- Qsymia outperforms older non-GLP-1 options. Within the pre-GLP-1 generation of weight-loss drugs, Qsymia was and still is the most effective — more than phentermine alone, more than Contrave, more than Saxenda (the weakest GLP-1).
Qsymia vs Zepbound
This is the most-searched comparison on the topic, and the cleanest efficacy mismatch.
| Dimension | Qsymia | Zepbound |
|---|---|---|
| Drug class | Stimulant + anticonvulsant | Dual GIP/GLP-1 agonist |
| Form | Daily oral capsule | Weekly subcutaneous injection |
| Mean weight loss | ~10% | ~21% |
| Controlled substance | Yes (Schedule IV) | No |
| REMS required | Yes | No |
| Main side effects | Tingling, dry mouth, cognitive slowing, insomnia | Nausea, diarrhea, constipation (mostly temporary) |
| Cash price | $55–$275 / mo | $1,086 retail, ~$299 telehealth |
| Pregnancy safety | Contraindicated (oral clefts) | Not recommended; insufficient human data |
Bottom line: Zepbound produces roughly 2× more weight loss without the controlled-substance classification or REMS paperwork. The reasonable cases for choosing Qsymia over Zepbound: strong cost sensitivity (generic Qsymia wins on monthly sticker), needle aversion (Zepbound is weekly SC injection), or GI intolerance of GLP-1s.
Qsymia vs Wegovy / Ozempic
Wegovy and Ozempic are the same active ingredient (semaglutide) — Wegovy is the higher-dose (2.4 mg) formulation approved specifically for weight loss, while Ozempic is approved for type 2 diabetes and prescribed off-label for weight loss at lower doses (typically 1 mg or 2 mg weekly). For weight-loss purposes, Wegovy is the on-label comparison.
| Dimension | Qsymia | Wegovy |
|---|---|---|
| Drug class | Stimulant + anticonvulsant | GLP-1 agonist |
| Form | Daily oral capsule | Weekly subcutaneous injection |
| Mean weight loss | ~10% | ~15% |
| Controlled substance | Yes (Schedule IV) | No |
| Indications | Adults + adolescents 12+ | Adults + adolescents 12+; also cardiovascular risk reduction |
| Cash price (brand) | $250 / mo | $1,349 / mo |
| Telehealth alternative | Generic via REMS pharmacy | Compounded semaglutide from $179/mo |
Wegovy has additionally been approved by the FDA for reducing the risk of major cardiovascular events (heart attack, stroke, CV death) in adults with established cardiovascular disease and obesity. Qsymia has no such cardiovascular indication.
Qsymia vs Contrave
Two older combination pills — both approved before the GLP-1 wave. This is the comparison for patients who want a pill, cannot tolerate GLP-1s, and want to avoid controlled substances.
| Dimension | Qsymia | Contrave |
|---|---|---|
| Ingredients | Phentermine + topiramate ER | Bupropion + naltrexone |
| Class | Stimulant + anticonvulsant | Dopamine/norepinephrine reuptake inhibitor + opioid antagonist |
| Mean weight loss | ~10% | ~6% |
| Controlled substance | Yes (Sch IV) | No |
| Seizure risk | Moderate (topiramate-related) | Elevated (bupropion lowers threshold) |
| Dosing | Once daily | Twice daily (2 tablets each time) |
| Cash price (brand) | $250 / mo | $700+ / mo |
When Contrave wins: Patient history of substance misuse (Contrave's naltrexone is actually indicated for alcohol/opioid dependence); patient already taking bupropion for depression or smoking cessation; aversion to controlled-substance status.
When Qsymia wins: Patient prioritizing maximum weight loss within the non-GLP-1 pill options; no seizure history; comfortable with REMS and Schedule IV status.
Qsymia vs Phentermine Alone
This is the comparison for patients who have been on phentermine before and are asking whether adding topiramate makes a meaningful difference.
| Dimension | Qsymia | Phentermine |
|---|---|---|
| Ingredients | Phentermine + topiramate ER (fixed ratio) | Phentermine hydrochloride alone |
| Phentermine dose | 3.75, 7.5, 11.25, or 15 mg | 15, 30, or 37.5 mg |
| Labeled duration | Long-term | Short-term (~12 weeks) |
| Mean weight loss | ~10% | ~5% |
| Appetite mechanism | Suppression + reward-modulation (both) | Suppression only |
| Cash price | $55–$275 / mo | $10–$40 / mo |
Notice one counterintuitive point: Qsymia at the maximum dose contains less phentermine than standalone phentermine tablets. The efficacy advantage of Qsymia comes from the topiramate, not from a larger stimulant dose. Patients looking to minimize stimulant exposure while still losing weight may actually prefer Qsymia 7.5/46 (7.5 mg phentermine) over standalone phentermine 30 mg.
Qsymia vs Saxenda
Saxenda is liraglutide, a daily-injection GLP-1 approved in 2014 — the first GLP-1 approved specifically for weight loss. Compared with the newer weekly GLP-1s, Saxenda is considered second-line today, but it remains on-market and insurance-covered more often than newer options.
| Dimension | Qsymia | Saxenda |
|---|---|---|
| Class | Stimulant + anticonvulsant | GLP-1 agonist |
| Mean weight loss | ~10% | ~7% |
| Form | Daily oral capsule | Daily subcutaneous injection |
| Controlled | Yes | No |
| Monthly brand cost | $250 | $1,349 |
Qsymia outperforms Saxenda in mean weight loss. Saxenda has the cleaner safety profile but is clinically outclassed by its own successor drugs (Wegovy, Zepbound) in the same drug class. For a patient choosing between Qsymia and a GLP-1, Saxenda is probably not the GLP-1 to choose — Wegovy or Zepbound has more favorable data.
Side Effects Compared
| Side effect | Qsymia | Zepbound | Wegovy | Contrave | Phentermine |
|---|---|---|---|---|---|
| Nausea | Uncommon | Common | Common | Common | Rare |
| Paresthesia | Common (20%) | Rare | Rare | Rare | Rare |
| Dry mouth | Common (19%) | Uncommon | Uncommon | Common | Very common |
| Insomnia | Common | Rare | Rare | Common | Very common |
| Cognitive slowing | Common (6–8%) | Rare | Rare | Uncommon | Rare |
| Heart-rate elevation | Common | Possible (mild) | Possible (mild) | Possible | Very common |
| Kidney stones | 1.5–2% | Rare | Rare | Rare | Rare |
| Seizure risk | Low (only on abrupt stop) | Rare | Rare | Elevated | Rare |
| Teratogenicity | Yes (REMS) | Insufficient data; not recommended | Insufficient data; not recommended | Not recommended | Not recommended |
Monthly Cost Compared
| Drug | Brand cash / mo | Generic / compounded / mo | Savings program |
|---|---|---|---|
| Qsymia | $220–$275 | $55–$85 | $98 via Engage |
| Zepbound | $1,086 | $299 (compounded) | Lilly Direct $499 |
| Wegovy | $1,349 | $179 (compounded) | Novo $500 card |
| Contrave | $700+ | Not yet generic | $99 via Currax |
| Saxenda | $1,349 | $249 (compounded liraglutide) | Novo $25 card |
| Phentermine | $40 | $10–$20 | N/A (already cheap) |
Who Each Drug Is Actually For
Oversimplified clinical positioning — not a substitute for clinician judgment:
- Zepbound — the patient who wants maximum weight loss, can handle a weekly injection, and isn't cost-constrained (or uses compounded telehealth).
- Wegovy — similar to Zepbound but for patients whose insurance covers Wegovy specifically, or who have cardiovascular disease (Wegovy has the CV indication).
- Qsymia — the patient who wants an oral pill, tolerates stimulants, prefers an older-generation drug with a long safety record, and is cost-sensitive enough that generic pricing matters.
- Saxenda — the patient whose insurance covers Saxenda specifically, or who has tried weekly GLP-1s and prefers daily.
- Contrave — the patient who wants a pill, avoids controlled substances, and has a history where naltrexone (alcohol, opioid) or bupropion (depression, smoking) is a double benefit.
- Phentermine alone — the patient who wants a short-term jumpstart (12 weeks), has a low starting BMI, and already tolerates stimulants.
For Most Qsymia Candidates, a GLP-1 Is a Better Match
Qsymia was FDA-approved in 2012 — a repurposed stimulant plus an anti-seizure drug. Since then, an entirely new drug class has redefined obesity medicine: GLP-1 receptor agonists. For most patients today, they are more effective and easier to manage.
- 2–3× more weight loss in trials (15–22% vs 7–10% with Qsymia)
- Not a controlled substance — no DEA schedule, no REMS enrollment
- Hormone-based (GLP-1 agonist) — no stimulant, no amphetamine lineage
- Daily oral tablet or once-weekly injection, delivered to your door
- Transparent pricing from $179/month with licensed US providers
- Cancel anytime — no long-term commitment
Licensed US clinicians · HIPAA protected · Medication shipped from US pharmacies
Frequently Asked Questions
Which works better, Qsymia or Zepbound?
In direct trial-to-trial comparison (cross-trial, not head-to-head), Zepbound (tirzepatide 15 mg) produced about 20.9% body-weight loss at 72 weeks in SURMOUNT-1, compared with roughly 9.8% for Qsymia 15/92 at 56 weeks in CONQUER. Zepbound produces approximately 2× more absolute weight loss. Zepbound is also not a controlled substance and does not have a REMS program. The main reason a patient might still choose Qsymia over Zepbound: it is an oral pill (vs weekly injection), and generic Qsymia is considerably cheaper than brand Zepbound.
Is Qsymia better than Wegovy?
For most patients, no — Wegovy (semaglutide 2.4 mg) produces roughly 15% body-weight loss in pivotal trials (STEP 1), versus about 10% for Qsymia at the maximum dose. Wegovy is also not a controlled substance and does not have a REMS. Qsymia retains an advantage if (1) the patient cannot tolerate GLP-1 gastrointestinal side effects, (2) the patient is cost-sensitive and generic Qsymia is covered or affordable, or (3) the patient has a medical contraindication to GLP-1 (medullary thyroid carcinoma history, MEN-2).
Qsymia vs Contrave — which is more effective?
Qsymia produces somewhat more weight loss than Contrave head-to-head: 9.8% vs roughly 6.1% placebo-subtracted at their pivotal endpoints. Both are older combination pills; neither is a GLP-1. Contrave combines naltrexone and bupropion, targeting reward circuitry rather than acting as a stimulant. Contrave is not a controlled substance, which some patients find easier. For pure weight-loss efficacy: Qsymia > Contrave. For safety profile simplicity: Contrave > Qsymia.
Qsymia vs phentermine alone — which is better?
Qsymia at maximum dose (15/92) produces about 9.8% placebo-subtracted weight loss at 56 weeks. Phentermine alone is labeled for short-term use (12 weeks) with expected weight loss around 5%. The combination with topiramate adds appetite-reward suppression and allows long-term use, substantially outperforming phentermine alone. Qsymia contains less phentermine per capsule (up to 15 mg) than standalone phentermine tablets (typically 15–37.5 mg), so the stimulant load can actually be lower with Qsymia despite producing more weight loss.
Is Qsymia the same as phentermine?
No. Phentermine is a single-ingredient short-term weight-loss drug. Qsymia combines phentermine with topiramate (an anti-seizure drug) in a fixed-ratio extended-release capsule, and is labeled for long-term use. A Qsymia 15/92 capsule contains 15 mg of phentermine — that is the phentermine dose within Qsymia; it is not separately adjustable. The two drugs are not interchangeable in either direction.
Which GLP-1 is most comparable to Qsymia as an oral pill?
Rybelsus (oral semaglutide, 3 / 7 / 14 mg) is currently the only FDA-approved GLP-1 in pill form, but it is approved for type 2 diabetes, not weight loss specifically. Orforglipron, Eli Lilly's oral GLP-1 for weight loss, has completed Phase 3 trials and is expected to be an oral weight-loss option in the near future. For oral-to-oral comparability today, Qsymia competes mostly with standalone phentermine or Contrave — the GLP-1 class remains predominantly injectable for weight-loss indications.
Can I switch from Qsymia to a GLP-1?
Yes. Switching is a clinical decision with two main considerations: (1) taper off Qsymia, especially from the 11.25/69 or 15/92 doses, rather than stopping cold — topiramate withdrawal can trigger rebound symptoms; (2) expect a washout week before initiating the GLP-1 so that side-effect assessment is cleaner. Most telehealth clinicians are familiar with this transition. Weight loss often continues during the switch, sometimes at a higher rate once the GLP-1 dose escalates.
Which weight-loss drug has the fewest side effects?
"Fewest" depends on what you mean. Saxenda (liraglutide, daily GLP-1) and oral semaglutide have the cleanest profiles in terms of serious adverse events but produce nausea and GI effects. Contrave causes less stimulation than Qsymia but can cause insomnia and, rarely, seizures. Orlistat has minimal systemic effects but uncomfortable GI effects (oily stools, urgency). No drug in this class is side-effect-free. In trial dropout rates, tirzepatide and semaglutide have the lowest discontinuation rates for side effects among the weight-loss approved drugs.
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