Research · 2 min read
Semaglutide Side Effects: What the Label Actually Reports
The 44% nausea figure gets quoted everywhere without the number that makes it readable — 16% of the placebo group reported it too. Here is the full table from the current label.
Key takeaways
- 44% reported nausea — and so did 16% of the placebo group, which is the number that makes the first one readable.
- 6.8% stopped treatment because of adverse reactions, against 3.2% on placebo: far fewer than the number who reported them.
- Nausea, vomiting and diarrhea are the three reactions the label names behind those discontinuations.
- The hypoglycemia figure applies to patients with type 2 diabetes, not to everyone.
- A reaction missing from the table did not necessarily never happen — it did not reach 2% and beat placebo in these trials.
- The tirzepatide table is not comparable: different trials, populations, dose arms and placebo rates, and no head-to-head.
The table, with its control
The current WEGOVY label reports adverse reactions in adults from its weight-reduction trials: 2,116 people on 2.4 mg once weekly against 1,261 on placebo. Every figure below is that comparison.
Nausea 44% against 16% on placebo. Diarrhea 30% against 16%. Vomiting 24% against 6%. Constipation 24% against 11%. Abdominal pain 20% against 10%. Headache 14% against 10%. Fatigue 11% against 5%.
The placebo column is doing a great deal of work here. Nausea at 16% and diarrhea at 16% among people receiving no active drug is a reminder that a symptom reported during a trial is not automatically caused by the treatment — and that a headline percentage quoted alone overstates what the drug added.
What made people stop
6.8% of patients on 2.4 mg permanently discontinued because of adverse reactions, against 3.2% on placebo. That is the number that answers the question most people are actually asking, and it is much smaller than the incidence figures.
The label names the three reactions most often behind those discontinuations, each with its placebo comparison: nausea 1.8% against 0.2%, vomiting 1.2% against 0%, and diarrhea 0.7% against 0.1%.
So while 44% reported nausea, fewer than two in a hundred stopped because of it. Both facts come from the same table and neither one is the whole picture on its own.
The rest of the list
Below the headline gastrointestinal effects the label reports dyspepsia 9% against 3%, dizziness 8% against 4%, abdominal distension 7% against 5%, eructation 7% against under 1%, flatulence 6% against 4%, gastroenteritis 6% against 4%, gastresophageal reflux disease 5% against 3% and gastritis 4% against 1%.
It also reports hypoglycemia in patients with type 2 diabetes at 6% against 2%, which is a population-specific figure and should not be read as a general risk.
These are reactions reported in at least 2% of treated patients and more often than on placebo. A reaction absent from the table is not a reaction that never happened; it is one that did not clear that bar in these trials.
Why you cannot put this beside the tirzepatide table
The companion page on this site reports tirzepatide's numbers from its own label, and they look smaller. They are not measuring the same thing.
The two come from different trials with different populations, different durations and different dose arms — one 2.4 mg arm here, three separate dose arms there — and the placebo groups differ too, 16% reporting nausea in these trials against 8% in those. Neither label reports a head-to-head, and a percentage only means anything against the control that ran beside it.
Reading the two tables as a league table is the error this site exists to argue against. What both labels support is the same practical point: the gastrointestinal effects concentrate early and the number who stop is far smaller than the number who report.
Sources
- WEGOVY (semaglutide) injection, for subcutaneous use — Highlights of Prescribing InformationTable 3, Adverse Reactions (≥2% and greater than placebo) in WEGOVY injection-treated adults with obesity or overweight for weight reduction: placebo N=1,261, WEGOVY 2.4 mg once weekly N=2,116; nausea 16 / 44%, diarrhea 16 / 30%, vomiting 6 / 24%, constipation 11 / 24%, abdominal pain 10 / 20%, headache 10 / 14%, fatigue 5 / 11%, dyspepsia 3 / 9%, dizziness 4 / 8%, abdominal distension 5 / 7%, eructation <1 / 7%, hypoglycemia in type 2 diabetes 2 / 6%, flatulence 4 / 6%, gastroenteritis 4 / 6%, gastresophageal reflux disease 3 / 5%, gastritis 1 / 4%. Section 6.1: 6.8% of patients on 2.4 mg and 3.2% on placebo permanently discontinued as a result of adverse reactions, with the most common causes nausea (1.8% versus 0.2%), vomiting (1.2% versus 0%) and diarrhea (0.7% versus 0.1%).
Frequently asked questions
How common is nausea on semaglutide?
The label reports 44% on 2.4 mg once weekly against 16% on placebo, in the adult weight-reduction trials.
How many people stopped because of side effects?
6.8% on 2.4 mg permanently discontinued because of adverse reactions, against 3.2% on placebo. Nausea accounted for 1.8%, vomiting 1.2% and diarrhea 0.7%.
Why is the placebo number so high?
That is what the trial measured: 16% of people receiving no active drug reported nausea and 16% reported diarrhea. It is the reason a headline percentage quoted alone overstates what the drug added.
Does the label report hypoglycemia?
Yes, at 6% against 2% on placebo, but specifically in patients with type 2 diabetes. It should not be read as a general figure.
Is semaglutide worse tolerated than tirzepatide?
Neither label answers that. The two report different trials, populations and dose arms, with different placebo rates, and no head-to-head appears in either. Comparing the two tables directly is not a valid reading of them.