Are GLP-1 safe
You are getting oriented.
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.
Safety is not a property a drug class has in the abstract — it is a set of documented findings attached to a specific product at a specific dose. For the approved GLP-1 medications those findings exist and are public: adverse reaction rates from trials, contraindications, and a boxed warning. That is what makes the question answerable for them and unanswerable for anything sold without a label.
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.
The boxed warning is the part most worth reading before starting rather than after. These products carry one regarding thyroid C-cell tumours observed in rodent studies, and they are contraindicated in people with a personal or family history of medullary thyroid carcinoma or Multiple Endocrine Neoplasia syndrome type 2. That is a condition to screen for beforehand, not a side effect that develops — a distinction that changes what you do with the information.
Side-by-side
Structural facts from each product’s prescribing information.
| Product | Active ingredient | Indication | Frequency | Start | Max labelled | Steps to max |
|---|---|---|---|---|---|---|
| Zepbound Eli Lilly | Tirzepatide | Weight management | Weekly | 2.5 mg | 15 mg | 6 |
| Mounjaro Eli Lilly | Tirzepatide | Type 2 diabetes | Weekly | 2.5 mg | 15 mg | 6 |
| Wegovy Novo Nordisk | Semaglutide | Weight management | Weekly | 0.25 mg | 2.4 mg | 5 |
| Ozempic Novo Nordisk | Semaglutide | Type 2 diabetes | Weekly | 0.25 mg | 2 mg | 4 |
| Saxenda Novo Nordisk | Liraglutide | Weight management | Daily | 0.6 mg | 3 mg | 5 |
| Trulicity Eli Lilly | Dulaglutide | Type 2 diabetes | Weekly | 0.75 mg | 4.5 mg | 4 |
Common questions
- Are compounded versions as safe?
- They have not been evaluated by the FDA for safety, efficacy or quality, so the honest answer is that the evidence which exists for approved products does not exist for them. That is a statement about available evidence, not an assertion that they are harmful.
- What about long-term safety?
- The labels record what was observed over the trial periods and through post-marketing surveillance. There is a separate page on this site covering what the long-term record does and does not contain.
- Who should not take these?
- The contraindications are stated in each prescribing information document and include the thyroid history above. Screening against them is a prescriber task, and this page is not a substitute for it.
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
- 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
- Rybelsus (Semaglutide) prescribing information — Novo Nordisk, label revised 20 May 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.