Injection-site reactions are the one GLP-1 side effect that depends on the pen rather than the stomach — and the labels' figures run from 0.2% to 13.9%. Ozempic's label reports 0.2%; Zepbound's up to 8%, forty times higher; Saxenda's 13.9%. Most of that spread comes from what each label counts and how often the drug is injected, not from one molecule being harsher on skin than another. The most specific finding in any of the documents is in the tirzepatide labels: reactions were far more frequent in people who had developed antibodies to the drug.
This page sets out the figure in each current US injection label, the placebo figure beside it, and what the labels say about antibodies. The labels were read on 11 October 2026 from DailyMed, using the manufacturers' own versions. It reports what the documents record; it does not advise on technique or treatment.
The rate in every current injection label
The "excess" column is glp1ledger's subtraction — drug minus placebo in the same pool — which no label prints. The "what is counted" column quotes each label's own examples.
| Label (effective date) | Injected | Placebo | Drug | Excess | What is counted |
|---|---|---|---|---|---|
| Saxenda (2026-02-25) | daily | 10.5% | 13.9% (3 mg) | 3.4 points | "injection site reaction" (table term) |
| Zepbound (2026-08-28) | weekly | 2% | 6% (5 mg) · 8% (10 mg) · 8% (15 mg) | 4–6 points | bruising, erythema, pruritus, pain, rash, reaction |
| Mounjaro (2026-08-27) | weekly | 0.4% | 3.2% | 2.8 points | not itemised in the text |
| Victoza (2025-10-14) | daily | not printed | about 2% | — | "e.g., injection site rash, erythema" |
| Wegovy injection (2026-06-18) | weekly | 1% | 1.4% (2.4 mg) | 0.4 points | pruritus, erythema, inflammation, induration, irritation |
| Trulicity (2026-06-16) | weekly | 0.0% | 0.5% | 0.5 points | "e.g., injection-site rash, erythema" |
| Ozempic injection (2026-06-01) | weekly | not printed | 0.2% | — | "e.g., injection-site discomfort, erythema" |
Trulicity's paediatric trial is the exception to its low adult figure: 3.9% and 3.8% on its two doses against 2.0% on placebo, two patients per drug arm. Mounjaro's figure is for its pool of placebo-controlled diabetes trials.
What the table does and does not show:
- Definitions drive the spread. Zepbound's grouped term includes bruising and pain; the Novo Nordisk labels list redness and itching as examples. A label that counts bruises will record more than one that does not.
- A daily injection gives seven times the chances. Saxenda and Victoza are daily; the rest weekly. Saxenda's placebo arm — people injecting a dummy pen every day — reported site reactions at 10.5%, more than any drug arm of a weekly product.
- The excess over placebo is small everywhere, at most about six points, and below one point for Wegovy and Trulicity.
The antibody finding
Peptide drugs can prompt the immune system to make antibodies against them. The tirzepatide labels report how that relates to skin reactions:
| Label | Developed antibodies | Site reactions, with antibodies | Site reactions, without |
|---|---|---|---|
| Zepbound, weight trials (Studies 1 and 2) | 64.5% (1,591 of 2,467) | 11.3% | 1% |
| Mounjaro, seven diabetes trials | not restated here | 4.6% (119 of 2,570) | 0.7% (18 of 2,455) |
On Zepbound's figures, a site reaction was about eleven times more frequent in people with antibodies than in people without — glp1ledger's ratio of the two printed percentages. The same label reports a similar, smaller gap for hypersensitivity reactions generally (6.2% against 3%).
The semaglutide and liraglutide labels describe the same link in less detail. Saxenda's states that antibodies "may be associated with a higher incidence of injection site reactions", and that in its trials these events "were usually classified as mild and resolved while patients continued on treatment"; neutralising antibodies were found in 1.2% (18 of 1,505) of people treated. The Wegovy label reports a link with allergic reactions rather than site reactions: 16% (8 of 50) with antibodies against 7% (114 of 1,659) without.
One caution the labels themselves print: the measured rate of antibodies "is highly dependent on the sensitivity and specificity of the assay", and differences in methods "preclude meaningful comparisons" with other studies. Zepbound's 64.5% cannot be set against another drug's antibody figure to say which is more immunogenic.
What the labels separate from a site reaction
Every label lists serious hypersensitivity reactions — anaphylaxis and angioedema (swelling of the face, lips, tongue or throat) — in a separate warning, not as an injection-site reaction. The Medication Guides tell patients to stop the medicine and get medical help right away for symptoms of a serious allergic reaction. A patch of redness at the site and a reaction spreading across the body are two different entries in the documents.
The research peptides sold online are a separate subject: their reactions were never measured in trials. Peptifact's page on peptide injection-site reactions covers that record. How the approved pens themselves differ, and how long each can be kept out of the fridge, is on GLP-1 pen storage and GLP-1 injections explained.
What this page cannot tell you
- The rates count anyone who reported a site reaction at least once, of any severity, over trials lasting months to years.
- Definitions differ by label, so the table compares documents more than drugs; no trial compared two GLP-1 pens for site reactions.
- The antibody figures show an association, not that antibodies cause the reactions; the labels state no mechanism.
- Compounded products and vials drawn into syringes were not studied in these trials, and their site-reaction rates are unknown.
Whether a reaction at the injection site calls for any change is a decision for the prescriber. Every other side effect in the class is on GLP-1 side effects, with the brand pages for Zepbound, Mounjaro and Wegovy.
Sources
- Prescribing information and Medication Guides read on DailyMed, 2026-10-11 (manufacturer label versions, effective dates as shown): ZEPBOUND (Eli Lilly, set ID 487cd7e7-434c-4925-99fa-aa80b1cc776b), Table 1, section 6.1 (injection site and hypersensitivity reactions) and 12.6; MOUNJARO (Eli Lilly, d2d7da5d-ad07-4228-955f-cf7e355c8cc0), section 6.1; WEGOVY (Novo Nordisk, ee06186f-2aa3-4990-a760-757579d8f77b), section 6.1; SAXENDA (Novo Nordisk, 3946d389-0926-4f77-a708-0acb8153b143), Table 2 and section 6.1 immunogenicity text; VICTOZA (Novo Nordisk, 5a9ef4ea-c76a-4d34-a604-27c5b505f5a4), section 6.1; TRULICITY (Eli Lilly, 463050bd-2b1c-40f5-b3c3-0a04bb433309), section 6.1; OZEMPIC injection (Novo Nordisk, adec4fd2-6858-4c99-91d4-531f5f2a2d79), section 6.1. All at dailymed.nlm.nih.gov.