Is Mounjaro or Qsymia better for weight loss?

Mounjaro reports 11.9% average weight loss and Qsymia 9.8%, 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, Mounjaro or Qsymia?

Qsymia, at $75 a month against $499 — a difference of $424 a month, or $5,587 over a year counting 13 fills a year for Mounjaro and 12 for Qsymia. Both figures are the maintenance price rather than an introductory rate.

Can you switch between Mounjaro and Qsymia?

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.

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Mounjaro (tirzepatide, diabetes label) vs Qsymia (phentermine/topiramate)

Verdict

Qsymia is the better choice of the two, winning on entry price (halfrx score 7.1 against 5.1).

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, Mounjaro (tirzepatide, diabetes label) or Qsymia (phentermine/topiramate)?

Mounjaro (tirzepatide, diabetes label) is $499 a month all-in, read from its own page on 2026-09-21; Qsymia (phentermine/topiramate) is $66–$75, read from its own page on 2026-09-22. At the maintenance dose the gap is $424 a month, which is $5,587 across a year, counting 13 fills for Mounjaro (tirzepatide, diabetes label) and 12 for Qsymia (phentermine/topiramate). Trial weight loss was 11.9% against 9.8%, 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 2026-09-21 and 2026-09-22. Neither carries an FTC action, a state action, a BBB F grade or an FDA warning letter. The published formula scores them 5.1 and 7.1 out of 10, arithmetic over the same stored fields rather than an editor's preference.

Head to head

Mounjaro (tirzepatide, diabetes label) against Qsymia (phentermine/topiramate), one row per axis, with the side that wins each axis marked.
What decides it	Mounjaro $499/mo	Qsymia $66–$75/mo
Entry priceQsymia (phentermine/topiramate) is $433/mo cheaper to start — $66 against $499.	—	✓ better here
Regulatory and complaint riskNeither carries a lawsuit, an FDA warning letter or a supply-risk flag.	tied	tied
Average weight loss in trialsMounjaro (tirzepatide, diabetes label) reports 11.9% and Qsymia (phentermine/topiramate) 9.8%, 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	Mounjaro	Qsymia
Mean weight loss in the cited trial	11.9%	9.8%
The trial that figure comes from	No percentage of body weight appears anywhere on the Mounjaro label, which has no weight-management section: every trial on it is a diabetes trial and reports weight in kilograms. This figure is worked out from the label's own kilograms — 11.2 kg lost from a 93.8 kg mean baseline at week 40 on 15 mg, in SURPASS-2 against semaglutide — and is an arithmetic step the label does not take.	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.
Maintenance dose	2.5 mg to 15 mg once weekly, set by blood sugar control	7.5 mg / 46 mg daily
Earliest week you reach it	—	week 3
Year one at the published price of every step	$6,487	No titration prices recorded

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 are one price at every dose, times the thirteen fills a 28-day month bills. The full arithmetic is published.

Go to Mounjaro ↗Go to Qsymia ↗

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

These are different molecules — tirzepatide against phentermine and topiramate — 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, Mounjaro (tirzepatide, diabetes label) is the 9th cheapest of 9 and Qsymia (phentermine/topiramate) the 1st — the cheapest of them all is $75.

Eli Lilly

Mounjaro (tirzepatide, diabetes label)

5.1

$499/mo all-in

verified 2026-09-21

Off-label for weightBoxed warning

Vivus

Qsymia (phentermine/topiramate)

7.1

$66–$75/mo all-in

verified 2026-09-22

Weaker moleculeREMS restrictedControlled substance

Mounjaro (tirzepatide, diabetes label)

Pros

+Same tirzepatide molecule as Zepbound, the most effective approved weight-loss agent.[4]
+On-label and readily covered if you have type 2 diabetes.[4]

Cons

−Off-label for weight loss without diabetes — expect insurance denial and prescriber reluctance.[4]
−Self-pay is $499 a month at every strength through LillyDirect, with no cheaper starting tier: Zepbound, the same molecule on the weight-loss label, is $299 at 2.5 mg and $449 at 7.5 mg and above through the same pharmacy. For weight loss, Zepbound is the cheaper route to the same molecule.[1]
−Weekly injection with the same GI side-effect profile.[4]

Sources

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

Mounjaro side effects →Qsymia side effects →Mounjaro dosage →Qsymia 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 Mounjaro

Everything on Qsymia

Mounjaro against Qsymia, answered

Is Mounjaro or Qsymia better for weight loss?: Mounjaro reports 11.9% average weight loss and Qsymia 9.8%, 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, Mounjaro or Qsymia?: Qsymia, at $75 a month against $499 — a difference of $424 a month, or $5,587 over a year counting 13 fills a year for Mounjaro and 12 for Qsymia. Both figures are the maintenance price rather than an introductory rate.
Can you switch between Mounjaro and Qsymia?: 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.