Qsymia vs Zepbound is a daily pill vs a weekly shot. Qsymia (phentermine and topiramate extended-release) is a once-daily capsule. Zepbound (tirzepatide) is a once-weekly injection. Both are FDA-approved for long-term weight loss, but they work in completely different ways, and Qsymia isn't a GLP-1.
In their own trials, Zepbound produced roughly twice the average weight loss. Qsymia costs far less: about $70 to $75 a month cash vs $299 to $699 a month for Zepbound. Below: how each works, trial results, side effects, who can't take each one, and what you'll pay in 2026.
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Qsymia vs Zepbound at a glance
| Qsymia (phentermine/topiramate ER) | Zepbound (tirzepatide) | |
|---|---|---|
| Form | Capsule, once a day in the morning | Injection, once a week |
| How it works | Phentermine (an appetite suppressant) plus topiramate (a seizure and migraine drug) | GIP and GLP-1 (two gut hormones) |
| Is it a GLP-1? | No | Yes (GIP and GLP-1) |
| FDA-approved for weight loss | Yes, adults with obesity or overweight plus a weight-related condition, and teens 12 and older with obesity | Yes, adults with obesity or overweight plus a weight-related condition |
| Other FDA-approved use | None | Moderate to severe sleep apnea in adults with obesity |
| Average weight loss in its label trials | 5.1% to 10.9% at 56 weeks, by dose (placebo 1.2% to 1.6%) | 15.0% to 20.9% at 72 weeks, adults without diabetes (placebo 3.1%) |
| Controlled substance | Yes, Schedule IV (phentermine) | No |
| Pregnancy | Not allowed; monthly pregnancy tests advised | May cause fetal harm; stop if you become pregnant |
| Cash price | $74.99 a month, or $210 for 90 days | $299 to $699 a month, by dose |
| Maker | VIVUS | Eli Lilly |
Sources for every row are in the sections below.
Neither is right for everyone. Zepbound usually wins on weight loss. Qsymia usually wins on price and on not needing a needle. Your health history decides a lot, because each one has its own list of people who shouldn't take it. If you want to see every option side by side, The RX Index's Find My GLP-1 Path tool is free, takes about 2 minutes and needs no signup.
See which weight-loss path fits you
How are Qsymia and Zepbound different?
They come at hunger from different directions:
- Qsymia combines two older drugs. Phentermine is a stimulant-type appetite suppressant related to amphetamines, which is why it's a Schedule IV controlled substance. Topiramate is a seizure and migraine medicine. You take one capsule each morning; evening doses can cause trouble sleeping.
- Zepbound copies two gut hormones, GIP and GLP-1, that help you feel full and slow how fast your stomach empties. It's the same medicine as Mounjaro, which is approved for type 2 diabetes.
Qsymia is also approved for teens 12 and older with obesity. Zepbound's label says its safety and effectiveness in children haven't been established.
Which works better for weight loss?
Zepbound, in its own trials. No trial has tested Qsymia against Zepbound, so these numbers come from each drug's FDA label and separate studies:
| Trial (from each FDA label) | Who was in it | Dose | Average weight lost |
|---|---|---|---|
| Qsymia Study 1 (56 weeks) | Adults with a BMI of 35 or higher | 3.75/23 mg / 15/92 mg daily | 5.1% / 10.9% (placebo 1.6%) |
| Qsymia Study 2 (56 weeks) | Adults with obesity or overweight plus 2 or more weight-related conditions | 7.5/46 mg / 15/92 mg daily | 7.8% / 9.8% (placebo 1.2%) |
| Zepbound Study 1 (72 weeks) | Adults with obesity or overweight, no diabetes | 5 mg / 10 mg / 15 mg weekly | 15.0% / 19.5% / 20.9% (placebo 3.1%) |
| Zepbound Study 2 (72 weeks) | Adults with obesity or overweight and type 2 diabetes | 10 mg / 15 mg weekly | 12.8% / 14.7% (placebo 3.2%) |
What this means for you:
- Zepbound's average results were about double Qsymia's at their top doses, though the trials differ in length and who enrolled.
- Qsymia has a built-in checkpoint. Its label says that if an adult hasn't lost at least 3% after 12 weeks on 7.5/46 mg, the dose goes up. If they haven't lost at least 5% after 12 weeks on the top dose, Qsymia should be stopped.
- Many people still did well on Qsymia. In Study 2, 62% to 70% of people taking it lost at least 5% of their weight, vs 21% on placebo.
Qsymia vs Zepbound side effects
The side effects are very different. Zepbound's are mostly in the gut. Qsymia's lean toward tingling, dry mouth and changes in taste and sleep.
| Side effect (each drug's own trials, not head to head) | Placebo | Qsymia 15/92 mg |
|---|---|---|
| Tingling (paraesthesia) | 2% | 20% |
| Dry mouth | 3% | 19% |
| Constipation | 6% | 16% |
| Altered taste (dysgeusia) | 1% | 9% |
| Trouble sleeping | 5% | 9% |
| Dizziness | 3% | 9% |
| Side effect (each drug's own trials, not head to head) | Placebo | Zepbound 5 mg / 15 mg |
|---|---|---|
| Nausea | 8% | 25% / 28% |
| Diarrhea | 8% | 19% / 23% |
| Constipation | 5% | 17% / 11% |
| Vomiting | 2% | 8% / 13% |
Qsymia warnings to know: it can raise heart rate, and its label also warns about mood changes and suicidal thoughts (a warning shared by seizure medicines), sudden eye problems including a type of glaucoma, trouble with memory or concentration, kidney stones and metabolic acidosis. Don't stop the top dose suddenly; the label calls for tapering because stopping abruptly may trigger a seizure.
Zepbound warnings to know: its boxed warning, the FDA's most serious kind, says it caused thyroid C-cell tumors in rodents, and it isn't known if that happens in people. Do not use Zepbound if you or a family member has had medullary thyroid cancer (MTC), or if you have Multiple Endocrine Neoplasia syndrome type 2 (MEN 2). Its label also warns about pancreatitis, gallbladder problems, severe stomach side effects and kidney injury from dehydration.
Get medical help right away for severe belly pain that won't go away, sudden eye pain or blurry vision, thoughts of self-harm, signs of an allergic reaction, or a lump or swelling in your neck. Our GLP-1 side effects comparison chart covers more drugs.
Who can't take Qsymia or Zepbound?
This is often what decides it.
| You can't take it if | Qsymia | Zepbound |
|---|---|---|
| You're pregnant | Yes, can't take it. The label advises a negative pregnancy test before starting and every month | Its label says it may cause fetal harm; stop when pregnancy is recognized |
| You have glaucoma | Yes, can't take it | Not on its list |
| You have an overactive thyroid (hyperthyroidism) | Yes, can't take it | Not on its list |
| You take an MAOI antidepressant, or stopped one in the last 14 days | Yes, can't take it | Not on its list |
| You or a family member had medullary thyroid cancer, or you have MEN 2 | Not on its list | Yes, can't take it |
| You've had a serious allergic reaction to it | Yes, can't take it | Yes, can't take it |
Two more practical differences:
- Qsymia is sold only through certified pharmacies under an FDA safety program (REMS), because topiramate can cause birth defects such as cleft lip and palate. Its label also says birth control pills may cause spotting with Qsymia but don't become less effective, so don't stop them.
- Zepbound can make birth control pills less reliable. Its label advises switching to a non-pill method, or adding a barrier method, for 4 weeks after you start and after each dose increase.
Can you take Qsymia and Zepbound together?
Not on your own. Qsymia's label says its safety and effectiveness with other weight-loss medicines haven't been established. Any combination would be off-label and is a prescriber's call. Our guide to taking phentermine with a GLP-1 covers what's known about pairing.
Qsymia vs Zepbound cost: which is cheaper?
Qsymia, by a lot. At the cash prices below, a year of Qsymia at the 90-day price comes to about $840, vs $5,388 for a year of Zepbound at $449 a month (our math).
| Qsymia | Zepbound | |
|---|---|---|
| Manufacturer cash price | $74.99 for 30 days through Qsymia Engage home delivery; $210 for 90 days ($70 a month) where 90-day prescriptions are allowed | $299 (2.5 mg), $399 (5 mg), $449 (7.5 to 15 mg) through LillyDirect if you refill within 45 days; otherwise $499 (7.5 mg) or $699 (10 to 15 mg) |
| Other cash options the maker lists | $65.99 for 30 days for Costco members; about $2.50 a day at retail pharmacies with a manufacturer discount | Self-pay is through LillyDirect |
| Extras | Shipping and handling on home-delivery orders, except 90-day online orders | Vials and KwikPens need needles or syringes bought separately |
| If your insurance covers it | Savings card: you pay the first $70 of your copay, then up to $65 off | As little as $25 for a 1- or 3-month supply with Lilly's savings card |
| List price | Not listed on the maker's savings page | $499 to $1,086.37 per fill |
Both makers' savings cards exclude people on Medicare, Medicaid and other government insurance. Qsymia's monthly savings card isn't available to California or Massachusetts residents. Zepbound's 2.5 mg dose is a starting dose only, so most people pay more after the first month.
Some insurance plans make you try cheaper weight-loss pills such as Qsymia before they'll cover Zepbound. For Zepbound, see Zepbound cost with insurance, does insurance cover Zepbound for weight loss and the cheapest ways to get Zepbound without insurance.
Compare weight-loss costs for your situation
Which should you ask your prescriber about?
| If this sounds like you | The option to ask about first |
|---|---|
| You want the most weight loss and can get or afford it | Zepbound. See is Zepbound worth it |
| Cost is the biggest barrier | Qsymia, at roughly $70 to $75 a month cash |
| You don't want needles | Qsymia, or a GLP-1 pill. See Wegovy pill vs Zepbound |
| You have obesity and sleep apnea | Zepbound, the only one of the two approved for sleep apnea |
| You have glaucoma, an overactive thyroid, or take an MAOI | Not Qsymia; those rule it out |
| You or a family member had medullary thyroid cancer, or you have MEN 2 | Not Zepbound; that rules it out |
| You could become pregnant | Talk it through carefully; Qsymia needs monthly pregnancy tests and reliable birth control |
| You have a seizure history or take seizure medicine | Ask your prescriber; topiramate interacts with some seizure drugs |
| Your insurer wants you to try a pill first | Qsymia may be one of the pills on that list; ask what your plan requires |
Still weighing other options? Our best Zepbound alternatives, phentermine vs GLP-1 and Contrave vs GLP-1 guides cover the rest.
Find the weight-loss option that fits you
What we actually verified
- Read the Qsymia prescribing information (revised March 2026) and the Zepbound prescribing information (revised August 2026) for uses, doses, contraindications, warnings, side-effect rates and trial results.
- Opened Qsymia's savings page and Lilly's Zepbound pricing and LillyDirect pages for cash prices and savings card terms.
- Did the yearly cost math ourselves.
All checks were done on November 2, 2026. What we did not do: get an insurer or pharmacy quote, check discount-card prices ourselves, or check pharmacy stock. Prices change, so confirm before you fill.
Frequently asked questions
Is Qsymia a GLP-1?
No. Qsymia is phentermine plus topiramate extended-release, a daily capsule. Zepbound is tirzepatide, a weekly shot that acts on GIP and GLP-1.
Which causes more weight loss, Qsymia or Zepbound?
Zepbound, in its own trials. Adults without diabetes lost 15.0% to 20.9% of their weight over 72 weeks on Zepbound. Adults on Qsymia lost 5.1% to 10.9% over 56 weeks, depending on dose and study. No trial has compared them directly.
Is Qsymia cheaper than Zepbound?
Yes. Qsymia's maker lists $74.99 for 30 days through home delivery, or $210 for 90 days. Zepbound costs $299 to $699 a month through LillyDirect, depending on dose.
Can you take Qsymia and Zepbound together?
Not without a prescriber. Qsymia's label says safety and effectiveness with other weight-loss medicines haven't been established. Don't add one to the other on your own.
Is Qsymia a controlled substance?
Yes. It contains phentermine, a Schedule IV controlled substance. Zepbound isn't a controlled substance.
Still not sure which path fits you? Take The RX Index's free Find My GLP-1 Path quiz — about 2 minutes, no signup.
Sources
- Qsymia prescribing information (VIVUS, revised March 2026; checked November 2, 2026)
- Zepbound prescribing information (Eli Lilly, revised August 2026; checked November 2, 2026)
- Qsymia: Multiple ways to save (checked November 2, 2026)
- Lilly: Zepbound cost information (list price) (checked November 2, 2026)
- LillyDirect: Zepbound self-pay (checked November 2, 2026)