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Semaglutide Hub

Side-effect rates and timeline

Label adverse reaction rates for Wegovy 2.4 mg, Wegovy 7.2 mg and Ozempic 0.5 and 1 mg against placebo, turned into absolute differences and number needed to harm, alongside the escalation timeline where the labels say reactions cluster.

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

Choose a data set and a symptom

Rates are cumulative over the whole trial, not per week.

Wegovy label Table 3: adults in the STEP weight-reduction trials, semaglutide 2.4 mg (N=2,116) vs placebo (N=1,261), reactions in 2% or more and more often than placebo.

Nausea: what the numbers mean

On 2.4 mg

44%

of participants reported it at any point in the trial

On placebo

16%

the background rate with the same diet and visits

Attributable to the drug

+28points

absolute difference, drug minus placebo

One extra case per

3.6people

relative risk 2.75x

When it tends to happen

  1. Weeks 1 to 4: 0.25 mg

    A step up. Labels report gastrointestinal reactions most often during dose escalation, in the weeks after each increase.

  2. Weeks 5 to 8: 0.5 mg

    A step up. Labels report gastrointestinal reactions most often during dose escalation, in the weeks after each increase.

  3. Weeks 9 to 12: 1 mg

    A step up. Labels report gastrointestinal reactions most often during dose escalation, in the weeks after each increase.

  4. Weeks 13 to 16: 1.7 mg

    A step up. Labels report gastrointestinal reactions most often during dose escalation, in the weeks after each increase.

  5. Weeks 17 onward: 2.4 mg maintenance

    Maintenance. In STEP 4, gastrointestinal events were still reported by 49.1% of people who continued 2.4 mg over 48 weeks versus 26.1% on placebo (PubMed 33755728), so they do not vanish, but new onsets cluster earlier.

In the pooled STEP 1 to 3 analysis (PubMed 34514682), 99.5% of gastrointestinal events on semaglutide were non-serious and 98.1% mild to moderate; they were transient and occurred most often during or shortly after dose escalation. 4.3% of semaglutide participants stopped treatment for gastrointestinal events.

Formulashown in full, nothing hidden
absolute difference (points) = rate on drug (%) - rate on placebo (%)
relative risk                = rate on drug / rate on placebo
number needed to harm        = 100 / absolute difference        (people treated for one extra case)

Rates are the percentage of participants who reported the reaction at any time during the trial. They are not weekly incidence, and they come from trial populations that may differ from you.

Assumptions, checked September 4, 2026

  • Wegovy 2.4 mg rates are the label's Table 3 (adults, STEP weight-reduction trials). Discontinuation for adverse reactions in those trials: 6.8% on Wegovy vs 3.2% on placebo.
  • Wegovy 7.2 mg rates are the label's STEP UP table; the label reports a subset of reactions for that dose. Discontinuation for adverse reactions at 7.2 mg: 5%.
  • Ozempic rates are the label's Table 1 (type 2 diabetes, placebo-controlled trials, 32.9 weeks mean exposure). Discontinuation for gastrointestinal reactions: 3.1% at 0.5 mg, 3.8% at 1 mg, 0.4% placebo.
  • The escalation timeline shows label dose steps only. No per-week rates are shown because the labels do not publish them; the timing statements are quoted from the labels and the pooled STEP tolerability analysis.
  • Compounded semaglutide was not studied in these trials. Its side-effect profile is assumed, not measured.

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. Wegovy (semaglutide) injection and tablets prescribing information, revised 6/2026, DailyMed set id ee06186f-2aa3-4990-a760-757579d8f77b
  2. Ozempic (semaglutide) injection prescribing information, revised 1/2025, NDA 209637, Drugs@FDA
  3. Wharton S et al. Gastrointestinal tolerability of once-weekly semaglutide 2.4 mg (STEP 1 to 3 pooled). Diabetes Obes Metab 2022. PubMed 34514682
  4. Once-weekly semaglutide 7.2 mg in adults with obesity (STEP UP). Lancet Diabetes Endocrinol 2025. PubMed 40961952

Read before you use it

Guides for this calculator

Semaglutide side effects by the numbers: STEP rates, placebo rates and when they happen

The adverse reaction tables from the Wegovy and Ozempic labels, the pooled STEP 1 to 3 tolerability analysis, and what the trials say about timing, with the arithmetic that turns a percentage into a personal risk.

Updated September 4, 2026

Educational, not medical advice. Read the medical disclaimer.