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Tirzepatide vs semaglutide side effects

You are deciding between two options.

Reference and calculator, not medical advice. Dosing figures below are transcribed from FDA-approved prescribing information and link back to it. Last reviewed August 2026.

Before any comparison: the adverse-reaction rates in these two labels come from different trials, in different populations, at different times. They were never designed to be compared against each other, and lining the percentages up side by side produces a number that looks rigorous and is not.

This is the single most common error in content on this topic. A rate of 39% in one trial and 35% in another does not establish that one product causes more nausea — only a head-to-head trial randomising people between the two can support that, and each label reports only its own studies against its own placebo group.

Listed in the prescribing information

Common adverse reactions listed for GLP-1 receptor agonists as a class.

These products carry a boxed warning regarding thyroid C-cell tumours observed in rodent studies, and are contraindicated in people with a personal or family history of medullary thyroid carcinoma or MEN 2. Read the full prescribing information for your specific product and discuss it with your prescriber — this summary is not complete and is not a substitute for that document.

What can be said from the labels is structural, and it is genuinely useful. Both are dominated by gastrointestinal reactions. Both build four-week holds into the escalation schedule specifically to limit them. Both list hair loss and attribute it to weight reduction rather than to the drug.

What each label actually reports

Incidence figures come from the adverse-reaction sections of the prescribing information. The two weight-management products report trial data; the diabetes products list alopecia only as a postmarketing report.

ProductReported inWomenMen
Wegovy SemaglutideClinical trials4%0.9%
Zepbound TirzepatideClinical trials7.1%0.5%
Ozempic SemaglutidePostmarketing reports onlyno denominatorno denominator
Mounjaro TirzepatidePostmarketing reports onlyno denominatorno denominator
Rybelsus Semaglutide (oral)Postmarketing reports onlyno denominatorno denominator
Saxenda LiraglutidePostmarketing reports onlyno denominatorno denominator
Trulicity DulaglutidePostmarketing reports onlyno denominatorno denominator

A postmarketing entry means the reaction has been reported after approval but the label gives no rate, because spontaneous reports have no denominator. It is not evidence that the rate is lower — only that it was not measured. Every figure above is checked against the label linked at the foot of this page.

Hair loss is the one place where a comparison is slightly better founded, because both labels break the figures down the same way — by sex, in weight-management trials. Even there the populations differ, so treat it as two separate observations that happen to agree rather than as a ranking.

The clearest number in any of the labels

Wegovy trials, women only, same measurement across three arms. Rate rises with dose while the label attributes the effect to weight reduction rather than to the drug.

Men in the same trials: 0% · 0% · 0.2%. The sex difference is larger than the dose difference, which is the part almost no summary of this topic mentions.

Why the women’s figure for 2.4 mg differs from the table above: these three arms come from the 7.2 mg trial programme, while the other figure is pooled from three earlier weight-management trials. Both are in the label and both report 3.3% overall at 2.4 mg — the sex split differs because the trial populations do. Both are shown rather than picking the more striking one.

Common questions

So which one is easier to tolerate?
The labels cannot answer that, and neither can this page. What both support is that escalation speed drives most of what people experience, which is why holding at a step is such a common adjustment.
Do they share a boxed warning?
Both carry a boxed warning about thyroid C-cell tumours observed in rodent studies, and both are contraindicated in people with a personal or family history of medullary thyroid carcinoma or MEN 2.
Does the extra GIP target add side effects?
Not something the labels establish. Tirzepatide’s adverse-reaction profile is reported from its own trials, not as a comparison against a GLP-1-only product.
Where can I read the actual numbers?
Section 6 of each label, linked at the foot of this page. That is where every figure quoted on this site comes from, and it is more readable than its reputation suggests.

Sources and last review

Every dosing figure on this page is transcribed from an FDA-approved label and links back to it. Conversions are arithmetic you can repeat by hand. Nothing here is reviewed by a clinician, and this site does not employ one — which is exactly why what I do publish stays traceable to its source.

Transcribed from the labels above and checked by me — Gavin, who builds this site, takes a GLP-1, and is not a clinician. Last reviewed August 2026. Found an error? [email protected] — I treat corrections as bugs. How this site is built and funded.

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