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Tirzepatide Hub

Side-effect rates by dose

Pick the maintenance dose on your prescription and see the adverse reaction table from the Zepbound label (pooled SURMOUNT-1 and SURMOUNT-2) or the Mounjaro label (SURPASS-1 and SURPASS-5) for that arm beside placebo, with the excess in percentage points and the number of people treated for one extra case. Enter your treatment week to see the dose in effect at the label minimum and whether you are still escalating.

By FormBlends editorial teamAssumptions checked September 4, 2026Runs in your browser; nothing is sent to a server

Inputs

Trial arms were fixed at 5, 10 or 15 mg. 7.5 and 12.5 mg are shown against the nearest arm above them.

week

Counting your first 2.5 mg injection as week 1. Shows the dose in effect at the label minimum schedule and whether you are still escalating.

Where you are

Choose the maintenance dose on your prescription to see the label's adverse reaction rates for that arm next to placebo, with the excess and the number of people treated for one extra case.

Formulashown in full, nothing hidden
excess (percentage points)  = arm % - placebo %
one extra case per          = 100 / excess   (number needed to harm)
approximate count           = arm % / 100 x arm N
dose at week w (label min)  = min(2.5 + 2.5 x floor((w - 1) / 4), maintenance dose)

Example: Zepbound 15 mg nausea 28% versus placebo 8% is an excess of 20 points, so about one extra person in five reports nausea because of the drug. Of 941 people in that arm, roughly 263 reported it.

Assumptions, checked September 4, 2026

  • Zepbound rates are Table 1 of section 6.1: reactions in at least 2% of Zepbound patients and more common than placebo, pooled from Study 1 (SURMOUNT-1, no diabetes) and Study 2 (SURMOUNT-2, type 2 diabetes), 2,519 treated patients, up to 72 weeks.
  • Mounjaro rates are Table 1 of its section 6.1: reactions in at least 5% of patients, pooled from SURPASS-1 and SURPASS-5 in type 2 diabetes, mean exposure 36.6 weeks. Different population, different threshold, not comparable to the Zepbound table.
  • Trial arms were fixed doses. Someone prescribed 7.5 mg is shown the 10 mg arm and someone on 12.5 mg the 15 mg arm because the label has no separate rows for those steps.
  • Week-to-dose mapping assumes the label minimum of 4 weeks per step. If your prescriber held a step longer, use the titration planner for your real dates.
  • Number needed to harm is a rounding of 100 / excess and ignores confidence intervals; treat it as a way to read the table, not a precise risk.

This calculator is an arithmetic aid for medication a licensed prescriber has already prescribed. It does not recommend a dose. Confirm any result with your prescriber or pharmacist before use.

Sources

  1. Zepbound (tirzepatide) prescribing information, Eli Lilly, DailyMed set id 487cd7e7-434c-4925-99fa-aa80b1cc776b, revised 08/2026
  2. Mounjaro (tirzepatide) prescribing information, Eli Lilly, DailyMed set id d2d7da5d-ad07-4228-955f-cf7e355c8cc0, revised 08/2026
  3. Jastreboff AM et al. Tirzepatide Once Weekly for the Treatment of Obesity (SURMOUNT-1). N Engl J Med 2022;387:205-216. PubMed 35658024

Read before you use it

Guides for this calculator

Tirzepatide side effects by dose: the label table, read properly

Adverse reaction rates for 5, 10 and 15 mg versus placebo from the Zepbound label, what the label says about timing, discontinuation rates, and how to read percentages without scaring yourself.

Updated September 4, 2026

Educational, not medical advice. Read the medical disclaimer.