Side effects of GLP-1 shots
You are dealing with a symptom and want to know if it is expected.
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.
Injection site reactions appear on the list below and belong to this route specifically — a tablet cannot produce them. Everything else on the list is a class effect that does not depend on delivery: those follow from the drug's action on gastric emptying and appetite signalling, which is the same whether it was injected or swallowed.
Listed in the prescribing information
Common adverse reactions listed for GLP-1 receptor agonists as a class.
- NauseaMost commonly reported; typically worst after a dose increase.
- DiarrhoeaGastrointestinal effects are the most frequently listed category.
- VomitingReported more often at higher doses.
- ConstipationRelated to slowed gastric emptying.
- Abdominal painListed across the class.
- Injection site reactionsApplies to injectable products only.
- FatigueListed in product labelling.
- HeadacheListed in product labelling.
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.
Gastrointestinal effects are reported across the class as worst in the days after a dose increase and easing as the body adjusts — which is the entire reason the schedule below is stepped rather than immediate. Anything severe, persistent or unexpected is a reason to contact your prescriber rather than to keep reading.
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.
- Zepbound (Tirzepatide) prescribing information — Eli Lilly, label revised 6 May 2026, checked 7 August 2026
- Mounjaro (Tirzepatide) prescribing information — Eli Lilly, label revised 6 May 2026, checked 7 August 2026
- Wegovy (Semaglutide) prescribing information — Novo Nordisk, label revised 30 June 2026, checked 7 August 2026
- Ozempic (Semaglutide) prescribing information — Novo Nordisk, label revised 10 June 2026, checked 7 August 2026
- Rybelsus (Semaglutide) prescribing information — Novo Nordisk, label revised 20 May 2026, checked 7 August 2026
- Saxenda (Liraglutide) prescribing information — Novo Nordisk, label revised 15 June 2026, checked 7 August 2026
- Trulicity (Dulaglutide) prescribing information — Eli Lilly, label revised 25 March 2026, checked 7 August 2026
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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