Semaglutide vs Tirzepatide: Weight Loss and Side Effects

Two weekly injections, one direct comparison

Tirzepatide produced more average weight loss than semaglutide at the doses tested in a direct trial. Both can help with appetite; tolerability, ongoing cost and access also shape the choice.

The study answers a weight-loss question. It does not supply an equivalent switching dose or predict which medicine will feel better for you.

Compare side effects ↗ Brands and differences ↗

SURMOUNT-5 72 weeks · one direct trial

Average loss of starting weight

Tirzepatide 10 or 15 mg weekly

20.2 %

Semaglutide 1.7 or 2.4 mg weekly

13.7 %

0% 25%

6.5 percentage points more average weight loss with tirzepatide.

Weight loss in the same trial

The visual compares people in the same 72-week study, rather than percentages from unrelated trials. Doses were gradually increased toward the highest trial dose participants could tolerate. They knew which medicine they received, and Lilly funded the study. The figures are adjusted group averages, not targets for every participant. SURMOUNT-5.

The result applies to the tested weekly injections. The newer 7.2 mg Wegovy injection and semaglutide tablets were outside this comparison, so it cannot settle every product or dose available today. Current Wegovy label.

What about the dose?

Their milligram doses are not equivalent. For adult weight management, the US labels describe:

Both labels use gradual dose increases, considering response and tolerability.

Wegovy’s current label also allows 7.2 mg when additional weight reduction is clinically indicated after at least four weeks tolerating 2.4 mg. Four-week dose stages are not the total treatment length. Continuing treatment is reviewed with the prescriber. These are product-label contexts, not a switching table. A first month with little weight change is not comparable with the long-term results above. Wegovy dosing, Zepbound dosing.

The main differences

The ingredient name and brand name answer different questions. These are the main US injection brands:

Both influence appetite and blood-sugar control. Two hormone targets do not mean twice the effect, and brands sharing an ingredient can have different approved uses, doses and devices. Ozempic, Mounjaro.

If diabetes control is the main goal, there is separate evidence: SURPASS-2 found greater average blood-sugar and weight reductions with tirzepatide 5/10/15 mg than with semaglutide 1 mg over 40 weeks. That study did not compare tirzepatide with every semaglutide dose available today. Original diabetes trial.

Why weekly doses build up

Returning hunger is not a dose-conversion tool. In a 60-week semaglutide study, participants still ate less at laboratory meals even when later appetite-rating differences from placebo were unclear. Hunger, measured drug exposure and long-term weight change are different outcomes. Original appetite study.

Semaglutide’s half-life is about one week; tirzepatide’s is about five to six days in the Zepbound label. Half-life describes the later decline in drug level. Some medicine remains when the next weekly dose arrives, so repeated doses build toward a recurring pattern. Wegovy, Zepbound.

Compare their example curves to see that overlap. A hungrier day does not tell you that the medicine is gone, and a higher curve does not directly predict appetite suppression. The semaglutide guide explains this distinction; the tirzepatide guide explains its weekly timing.

Side effects

Switching does not guarantee fewer stomach problems. In SURMOUNT-5, nausea was similarly common; vomiting was reported less often with tirzepatide. Most digestive events were mild or moderate and occurred during dose increases. Original study.

Percentages are participants reporting each non-serious event at least once in the same 72-week trial, not weekly odds: 376 received semaglutide and 374 tirzepatide. They do not predict how a particular person will tolerate a switch. Posted SURMOUNT-5 results.

One practical difference is oral hormonal contraception: tirzepatide can reduce its effectiveness. Its label advises a non-oral method or added barrier protection for four weeks after starting and after each dose increase. Both medicines also carry important precautions involving pancreatitis, gallbladder disease, dehydration and certain thyroid-cancer histories. Severe or persistent symptoms need medical advice. Zepbound sections 4–8, Wegovy sections 4–6.

Cost and availability

Compare the ongoing cost of the actual prescribed product and dose, including coverage and reliable pharmacy supply. A medicine that is tolerated and consistently available may be more practical than a better trial average that cannot be sustained.

Compounded preparations are not FDA-approved equivalents. Their concentrations and instructions can differ, and FDA has reported dosing errors. A syringe marking or vial price is not enough to compare doses or products. FDA guidance.

What happens after stopping?

Plan for maintenance as well as weight loss. Separate withdrawal studies found regain after either medicine stopped:

• Semaglutide: participants regained about two-thirds of their prior loss over the year after treatment and structured lifestyle support stopped. STEP-1 extension.
• Tirzepatide: people switched to placebo regained weight, while those continuing treatment lost more. SURMOUNT-4.

Different study designs mean these results cannot rank which medicine causes more regain.

Frequently asked questions

Can you take semaglutide and tirzepatide together?

The Wegovy and Zepbound labels do not recommend combining these treatments. A comparison chart is not a combined-treatment schedule.

Is there an equivalent dose when switching?

Neither product label provides a semaglutide-to-tirzepatide conversion. A prescriber plans the switch around the current product, treatment response and tolerability.

Does stronger appetite suppression always mean better results?

No. Appetite is useful to discuss, but it is not a direct measure of drug level or long-term benefit. Review weight, blood sugar where relevant, nutrition and side effects rather than judging treatment by hunger alone.

Sources and study context

Checked October 11, 2026. US injection labels provide the product context; tablet formulations have separate instructions.

• SURMOUNT-5, Aronne et al., NEJM (2025): direct weight-loss comparison, trial doses and population. Posted trial results provide digestive-event participant counts, with denominators of 374 and 376; the table uses people affected, not the number of episodes.
• Wegovy US prescribing information and Zepbound US prescribing information: adult weight-management dosing, timing, precautions and contraception. Wegovy’s 7.2 mg option was not studied in SURMOUNT-5.
• Ozempic injection label and Mounjaro label: type 2 diabetes product context.
• SURPASS-2, Frías et al., NEJM (2021): 1,879 adults with type 2 diabetes; tirzepatide 5/10/15 mg versus semaglutide 1 mg over 40 weeks.
• 60-week semaglutide appetite study (2026): helps explain why hunger alone is an incomplete measure of benefit; reduced laboratory food intake persisted despite less clear later subjective appetite differences.
• STEP-1 extension (2022) and SURMOUNT-4 (2024): separate treatment-withdrawal studies.
• FDA concerns about unapproved GLP-1 drugs: compounded-product and dosing-error context.