Peptide basics

Tirzepatide adverse-event reports by year, and what the curve measures

This page describes a time series of report counts and the reasons it cannot be read as a risk trend. It makes no claim about whether tirzepatide is safe or harmful, and it does not advise on symptoms — that requires someone who can examine you.

The series, and the queries behind it

Counting by receipt date on the openFDA adverse event endpoint gives an annual report count per product string. For MOUNJARO in the extract dated 28 April 2026 the yearly totals were 5,015 (2022), 20,691 (2023), 22,001 (2024), 30,388 (2025) and 6,664 for the part of 2026 the extract covers — all counts of reports received, not of verified events.¹

For ZEPBOUND in the same extract they were 37 (2023), 10,547 (2024), 30,799 (2025) and 12,190 for the partial 2026 — again reports received, with no denominator attached and no causal assessment behind any of them.²

Under the generic string TIRZEPATIDE the whole record is 2,641 reports, rising from 22 in 2022 to 1,391 in 2025 — two orders of magnitude smaller than the brand strings for the same molecule, which is a fact about how reporters write product names rather than about the molecule.³

The curve and the launch dates are the same curve

Mounjaro's original application, NDA215866, has an approval status date of 13 May 2022. Its report series is negligible before 2022 and 5,015 in the calendar year it launched.⁵¹

Zepbound's application, NDA217806, has an approval status date of 8 November 2023. Its report series is 37 for 2023 — the seven weeks it was on the market — and 10,547 for its first full year. Read as risk, that is a 285-fold increase in danger over one new year's eve. Read as uptake, it is a product going on sale.⁶²

• More people taking a product means more people with something to report.
• Manufacturers must forward reports that reach them, so a manufacturer with more customers files more reports.
• Media coverage and litigation advertising raise reporting independently of both.
• None of these three is visible in the count, and all three moved sharply across this window.⁷⁸

The shape is also consistent with what has been measured across FAERS generally. Hoffman and colleagues looked at 334,984 reports for 62 drugs approved between 2006 and 2010 and found the typical contemporary pattern is a rise over the first three quarters after approval and then a broadly stable count — a description of reporting behaviour after a launch, not of a hazard that grows and then plateaus.⁸

What the pre-approval rows tell you

The ZEPBOUND series contains single-digit counts for 2015, 2017, 2018, 2019, 2020, 2021 and 2022 — years entirely before the product existed as an approved drug. MOUNJARO carries similar small counts from 2016 onwards.¹²

The receipt date records when FDA first received a report in a case series, and a case that is later amended keeps its original receipt date. Together with the duplicate and incomplete reports FDA acknowledges are present, that is enough to put rows in a time series that cannot correspond to events involving the product named. We are not able to reconstruct the origin of any individual one of these rows from the public API.¹⁰⁷

What is in the reports themselves

Ranking reaction terms under the generic TIRZEPATIDE string in the same extract puts PRODUCT TAMPERING first at 408 reports, ahead of NAUSEA 327, VOMITING 279 and DIARRHOEA 231 — a ranking that describes what reporters wrote about products, not a hierarchy of physiological effects. Those tampering reports are concentrated in 2024 (175) and 2025 (229).⁴

A term appearing at the top of a ranked list therefore says nothing about how common the underlying thing is among people taking the drug. It says that reports mentioning it were filed, in a period when compounded and unapproved versions of this molecule were widely discussed.⁴⁷

Where a denominator does exist

SURMOUNT-1 randomised 2,539 adults with obesity or overweight without diabetes across three tirzepatide groups and placebo for 72 weeks, and reported adverse events against that placebo arm. Adverse events caused treatment discontinuation in 4.3%, 7.1% and 6.2% of participants in the three tirzepatide groups and 2.6% of those receiving placebo.⁹

Those percentages have a denominator, a comparison group and a defined follow-up window. They are not larger or more alarming than the FAERS counts; they are a different kind of number, and they are the kind that supports a statement about how often something happened.⁹

Tirzepatide has two approved US products, a phase 3 record and a labelled adverse-reaction table. Where any of those can answer a question, a report count should not be the source quoted.

Common questions