What happens if you stop Qsymia or Zepbound?

Zepbound's label includes a trial that stopped the drug on purpose; Qsymia's does not, which is a difference in what is known rather than in what happens. On Zepbound's label, the people randomly assigned to stop gained 14% of body weight over the following 12 months while those who carried on lost 5.5% more. That figure belongs to Zepbound's trial, so this page does not apply it to Qsymia.

Is Qsymia or Zepbound better for weight loss?

Qsymia reports 9.8% average weight loss and Zepbound 20.9%, each from its own trial. The two were not compared against each other, so the higher figure is not a result of a head-to-head and this page does not present it as one. What is comparable is what each costs, below.

Which is cheaper, Qsymia or Zepbound?

Qsymia, at $75 a month against $449 — a difference of $374 a month, or $4,937 over a year counting 12 fills a year for Qsymia and 13 for Zepbound. Both figures are the maintenance price rather than an introductory rate.

Can you switch between Qsymia and Zepbound?

They are different molecules, so this is a change of medication rather than of brand, and the one you move to is started on its own dosing schedule.

← All providers and medications

Qsymia (phentermine/topiramate) vs Zepbound (tirzepatide)

Verdict

Qsymia comes out ahead on this table, winning on entry price. Zepbound scores higher on the published halfrx formula, 7.3 against 7.1; the formula takes in more than this table does.

Computed from the stored fields, so it moves when a price does. Nothing here is written by hand or by a model.

Which is cheaper, Qsymia (phentermine/topiramate) or Zepbound (tirzepatide)?

Qsymia (phentermine/topiramate) is $66–$75 a month all-in, read from its own page on 2026-09-22; Zepbound (tirzepatide) is $299–$699, read from its own page on 2026-08-19. At the maintenance dose the gap is $374 a month, which is $4,937 across a year, counting 12 fills for Qsymia (phentermine/topiramate) and 13 for Zepbound (tirzepatide). Trial weight loss was 9.8% against 20.9%, from separate trials with different populations, so the gap is not a measured difference between the two. Every axis below is computed from stored fields rather than written by hand, so the comparison moves when a price does. They were last checked on 2026-09-22 and 2026-08-19. Neither carries an FTC action, a state action, a BBB F grade or an FDA warning letter. The published formula scores them 7.1 and 7.3 out of 10, arithmetic over the same stored fields rather than an editor's preference.

Head to head

Qsymia (phentermine/topiramate) against Zepbound (tirzepatide), one row per axis, with the side that wins each axis marked.
What decides it	Qsymia $66–$75/mo	Zepbound $299–$699/mo
Entry priceQsymia (phentermine/topiramate) is $233/mo cheaper to start — $66 against $299.	✓ better here	—
Regulatory and complaint riskNeither carries a lawsuit, an FDA warning letter or a supply-risk flag.	tied	tied
Average weight loss in trialsQsymia (phentermine/topiramate) reports 9.8% and Zepbound (tirzepatide) 20.9%, each from its own trial. They were not compared against each other, and the populations, durations and endpoints differ, so the higher number is not a better result — it is a different study.	not comparable	not comparable

What the trials, the titration and a year actually say

Axis	Qsymia	Zepbound
Mean weight loss in the cited trial	9.8%	20.9%
The trial that figure comes from	CONQUER, Study 2 on the label, 56 weeks: 9.8% mean weight loss at the 15 mg/92 mg dose against 1.2% on placebo, intention-to-treat.	SURMOUNT-1, Study 1 on the label, 72 weeks: 20.9% mean weight loss at 15 mg against 3.1% on placebo, intention-to-treat.
Maintenance dose	7.5 mg / 46 mg daily	5 mg, 10 mg or 15 mg once weekly
Earliest week you reach it	week 3	week 5
Year one at the published price of every step	No titration prices recorded	$5,637

Trial percentages are quoted from the label or the named trial beside them. They are not a head-to-head result: different populations, different durations, different endpoints. That is why the comparison above scores this axis as not comparable rather than awarding it to the higher number. The year-one figures walk each titration step at its published price and count the thirteen fills a 28-day month bills. The full arithmetic is published.

Go to Qsymia ↗Go to Zepbound ↗

Read the price gap carefully: these two are not the same purchase

These are different molecules — phentermine and topiramate against tirzepatide — so this is a comparison of two treatments, not of two prices for one.
Against every medication on this site with a verified maintenance price, Qsymia (phentermine/topiramate) is the 1st cheapest of 9 and Zepbound (tirzepatide) the 8th — the cheapest of them all is $75.

Vivus

Qsymia (phentermine/topiramate)

7.1

$66–$75/mo all-in

verified 2026-09-22

Weaker moleculeREMS restrictedControlled substance

Eli Lilly

Zepbound (tirzepatide)

7.3

$299–$699/mo all-in

verified 2026-08-19

Price conditional on refill timingBoxed warning

Qsymia (phentermine/topiramate)

Pros

+9.8% mean weight loss at the top dose in CONQUER, intention-to-treat — the strongest result available from an oral non-GLP-1 drug.[2]
+$74.99/mo through Qsymia Engage home delivery for anyone, $65.99 for Costco members, and generic phentermine/topiramate ER runs roughly $50–$100 — an order of magnitude under branded GLP-1 list prices.[1]
+Approved down to age 12, as Wegovy and Saxenda are; Zepbound is for adults only.[2]

Cons

−Topiramate raises the risk of oral clefts when taken in the first trimester. The label recommends a negative pregnancy test before starting and every month during treatment, with effective contraception, and Qsymia is dispensed only through pharmacies certified under an FDA REMS.[6]
−Phentermine is a controlled substance with cardiovascular contraindications.[2]
−Cognitive side effects — word-finding difficulty and trouble concentrating — are common enough to be a frequent reason people stop.[2]
−Its 9.8% in CONQUER is under half the 20.9% tirzepatide reached in SURMOUNT-1 on Zepbound's label, a separate trial in a different population, so this is not a head-to-head result.[7]

Sources

Zepbound (tirzepatide)

Pros

+Highest average weight loss of any approved medication — around 20.9% at the 15 mg dose in SURMOUNT-1.[2]
+Dual GIP/GLP-1 agonist, a different mechanism from semaglutide, so it often works for people semaglutide failed.[2]
+$299/mo at the starting dose direct from Lilly against a $1,086 list price, with home delivery of vials or pens at the same price.[1]
+Also approved for obstructive sleep apnea, which can unlock insurance coverage that a weight indication alone would not.[2]
+If you are commercially insured with coverage, Lilly's card can bring it to as little as $25 a month.[1]

Cons

−Weekly injection with the usual GI side effects — nausea, vomiting, diarrhea and constipation are the common discontinuation reasons.[2]
−The advertised $449 ceiling is conditional. It holds only while you refill within 45 days; lapse once and 10 mg and above cost $699 — 56% more than the number in the advert.[1]
−Lilly defines a month as 28 days, so a year is 13 fills, not 12. At $449 that is $5,837 a year against the $5,388 that 'per month' implies — $449 of hidden annual cost.[1]
−$1,086 list price if you have no coverage and do not use LillyDirect self-pay.[1]
−Weight regain after stopping is the documented norm, so the cost is ongoing rather than a course.[2]
−2.5 mg is a starting dose and is not approved for maintenance, so the $299 headline is a price nobody stays on.[1]

Sources

Qsymia side effects →Zepbound side effects →Qsymia dosage →Zepbound dosage →

Comparisons are computed from the fields on each card, not written by hand or by a model, so they change when the data does. Information only, not medical advice. halfrx may earn a commission from some links, which never changes what a comparison says.

Everything on Qsymia

Everything on Zepbound

Qsymia against Zepbound, answered

What happens if you stop Qsymia or Zepbound?: Zepbound's label includes a trial that stopped the drug on purpose; Qsymia's does not, which is a difference in what is known rather than in what happens. On Zepbound's label, the people randomly assigned to stop gained 14% of body weight over the following 12 months while those who carried on lost 5.5% more. That figure belongs to Zepbound's trial, so this page does not apply it to Qsymia.
Is Qsymia or Zepbound better for weight loss?: Qsymia reports 9.8% average weight loss and Zepbound 20.9%, each from its own trial. The two were not compared against each other, so the higher figure is not a result of a head-to-head and this page does not present it as one. What is comparable is what each costs, below.
Which is cheaper, Qsymia or Zepbound?: Qsymia, at $75 a month against $449 — a difference of $374 a month, or $4,937 over a year counting 12 fills a year for Qsymia and 13 for Zepbound. Both figures are the maintenance price rather than an introductory rate.
Can you switch between Qsymia and Zepbound?: They are different molecules, so this is a change of medication rather than of brand, and the one you move to is started on its own dosing schedule.