Every current GLP-1 label lists a prior serious hypersensitivity reaction to the medicine as a reason not to take it, and every label warns that serious reactions such as anaphylaxis and angioedema have been reported. For the injections the labels say to stop the medicine if a reaction occurs; Wegovy, Ozempic and Mounjaro also say to treat promptly per standard of care, and the Zepbound and Foundayo labels tell patients to seek medical attention promptly. Wegovy, Ozempic and Mounjaro advise caution in someone who has had anaphylaxis or angioedema with a different GLP-1 receptor agonist, because it is not known whether they are predisposed. Serious reactions are described as reported events; the Zepbound label puts the severe-reaction figure at 0.1% in its pooled weight-reduction studies. Anyone with swelling of the face, lips or throat, trouble breathing or a widespread rash should treat it as an emergency.
Why allergic reactions get their own label section
Most GLP-1 safety conversation centres on nausea, pancreatitis or the thyroid warning. Allergic reactions get less attention because they are uncommon, yet every label gives them a dedicated warning and a contraindication, and the wording tells you something practical: what the manufacturer wants a patient to do, and who should not start the medicine at all. This guide sets the current FDA-approved labeling side by side. It covers the five products most readers ask about, and it is not a diagnosis tool.
We reviewed the current prescribing information for Wegovy label (injection and tablets, revised 06/2026), the Ozempic label, the Mounjaro label (revised 08/2026), the Zepbound label (revised 08/2026) and the Foundayo label (orforglipron tablets, revised 07/2026). We checked each on 12 October 2026. The copy that came with your prescription, and the Medication Guide, are the documents that apply to you.
The label wording, product by product
| Medicine | Contraindication (section 4) | Hypersensitivity warning | What the label says to do |
|---|---|---|---|
| Wegovy (injection and tablets) | A prior serious hypersensitivity reaction to semaglutide. | Section 5.7: serious hypersensitivity reactions (for example anaphylaxis, angioedema) have been reported with Wegovy. | Discontinue Wegovy, treat promptly per standard of care, and monitor until signs and symptoms resolve. |
| Ozempic | A serious hypersensitivity reaction to semaglutide or to any of the excipients in Ozempic. | Section 5.8: serious hypersensitivity reactions (for example anaphylaxis, angioedema) have been reported in patients treated with Ozempic. | Discontinue Ozempic and treat promptly per standard of care. |
| Mounjaro | Known serious hypersensitivity to tirzepatide or any of the excipients in Mounjaro. | Section 5.4: serious hypersensitivity reactions (for example anaphylaxis, angioedema) have been reported in patients treated with Mounjaro. | Discontinue Mounjaro, treat promptly per standard of care, and monitor until signs and symptoms resolve. |
| Zepbound | Known serious hypersensitivity to tirzepatide or any of the excipients in Zepbound. | Section 5.6: postmarketing reports of serious hypersensitivity reactions (for example anaphylaxis, angioedema). | Advise patients to promptly seek medical attention and discontinue use of Zepbound. |
| Foundayo | Known serious hypersensitivity to orforglipron or any of the excipients in Foundayo. | Section 5.6: serious hypersensitivity reactions (for example anaphylaxis, angioedema) have been reported with GLP-1 receptor agonists. | Advise the patient to promptly seek medical attention and discontinue use of Foundayo. |
Two details are worth noticing. First, the contraindication is the firmest instruction in each label: it applies after a previous serious reaction to that specific medicine. Second, the Zepbound and Foundayo wording is directed at the patient (seek medical attention, stop the medicine), while the Wegovy, Ozempic and Mounjaro wording is written for the clinician (treat per standard of care, monitor until symptoms resolve). That is a difference in audience, not a disagreement about the medicine.
What counts as a serious reaction
The labels give two named examples: anaphylaxis and angioedema. Anaphylaxis is a rapid, whole-body allergic reaction, and angioedema is swelling of deeper layers of skin, often around the face, lips, tongue or throat. The labels do not publish a symptom checklist in the warning itself, so we have not invented one. If swelling of the face, lips, tongue or throat, breathing difficulty, faintness or a widespread hive-like rash appears after an injection or a tablet, treat it as an emergency and call emergency services; the labels’ instruction to seek prompt medical attention points the same way.
Not every skin reaction is a serious allergic reaction. Redness, itching or a lump at the injection site are common enough to appear in the adverse reaction tables. We discuss them below, but the label does not draw the line for you, and distinguishing a local reaction from a systemic one is a question for a clinician.
The earlier-reaction caution: other GLP-1 medicines
The Wegovy, Ozempic and Mounjaro labels share a second sentence that is easy to miss. They state that anaphylaxis and angioedema have been reported with other GLP-1 receptor agonists, and they advise caution in a patient with a history of anaphylaxis or angioedema with another GLP-1 receptor agonist, because it is unknown whether such patients will be predisposed to these reactions with that product. The Zepbound label similarly advises caution for patients with prior angioedema or anaphylaxis with a GLP-1 receptor agonist. In plain terms, a reaction to one GLP-1 medicine is something to tell the prescriber about before a switch, even though the label stops short of a contraindication across the whole class.
If you are thinking of moving between products, our guide to switching from an injection to an oral GLP-1 covers the transition instructions, and who should not take an oral GLP-1 lists the other contraindications that apply to the tablets.
How often do these reactions occur?
The labels are cautious about frequency, and so are we. The Wegovy, Ozempic and Mounjaro warnings do not give a trial frequency in the passages we reviewed. The Zepbound label does: it reports that in pooled weight-reduction Studies 1 and 2, 0.1% of Zepbound-treated patients had severe hypersensitivity reactions, compared with none on placebo. That figure is the label’s own, from its own pooled studies, and it should not be compared directly with a number from a different product’s program, because the trials, populations and definitions differ.
Antibodies and skin reactions
The Zepbound immunogenicity section (12.6) adds more detail. It reports that anti-tirzepatide antibodies were detected in 64.5% (1,591 of 2,467) of patients in the weight-reduction studies. Hypersensitivity reactions in the pooled studies were more frequent among patients who developed antibodies (6.2%) than among those who did not (3%), and injection site reactions were 11.3% versus 1%. The label also splits reactions by timing: immediate hypersensitivity (within one day) in 2.1% of Zepbound patients versus 0.4% on placebo, and non-immediate reactions in 3.5% versus 2.7%, most of them skin reactions such as rash and itching. The pooled injection-site-reaction table lists 2% for placebo, 6% for the 5 mg dose and 8% for each of the 10 mg and 15 mg doses.
The Ozempic label reports a much lower antibody figure: 32 of 3,150 (1%) Ozempic-treated patients developed antibodies to semaglutide, and 19 patients (0.6% of the overall population) developed antibodies that cross-reacted with native GLP-1. The two programs measured antibodies in different populations with different assays, so these percentages describe each label’s own data. We do not draw a ranking from them, and we are not aware of a label that says antibody status should change what a patient does.
Practical points before and after a first dose
- Tell the prescriber about any past reaction. That includes a reaction to a different GLP-1 medicine, since three of the labels specifically raise it.
- Know the excipient point. The Ozempic, Mounjaro, Zepbound and Foundayo contraindications extend to the excipients (inactive ingredients). If you have a known allergy to an ingredient, the pharmacist can check the full ingredient list in the label.
- Do not take a second dose if you suspect a serious reaction. The labels say to discontinue, and the Zepbound and Foundayo labels pair that with prompt medical attention.
- Keep the pen or tablet carton. The product name and strength help a clinician or pharmacist work out exactly what was taken.
- Report what happened. Telling your prescriber about even a local injection reaction lets them judge whether it is routine.
How this fits with other label warnings
An allergic reaction is separate from the gastrointestinal side effects most people meet first. Nausea and vomiting are discussed in our guide to oral GLP-1 side effects, and the volume-depletion warning is covered in dehydration and acute kidney injury. The boxed warning about thyroid tumors is a different category of risk altogether, and we set it out in the thyroid C-cell tumor warning. If a serious reaction occurs during a stretch of illness, tell the clinician about both, since dehydration and an allergic reaction can look alike on the surface.
Compounded products
All of the above refers to FDA-approved products. Compounded semaglutide and tirzepatide are not FDA-approved, are not covered by these labels, and may contain different excipients. We do not have a label to quote for them, so a patient with an allergy history should ask the dispensing pharmacy for the ingredient list. For background, see compounded semaglutide versus Wegovy. We have left prices out of this article because the question here is safety, not cost.
Common mistakes
- Treating a spreading rash or lip swelling as a nuisance. The labels name angioedema and anaphylaxis as the serious end of the range and instruct prompt medical attention.
- Assuming a reaction to one brand is irrelevant to another. Several labels explicitly advise caution after a reaction to another GLP-1 receptor agonist.
- Restarting after a serious reaction. The contraindication applies to a prior serious reaction to the same medicine.
- Quoting trial percentages across products. Each label reports its own programs, and the numbers are not interchangeable.
Questions people ask
Can I take a GLP-1 medicine if I am allergic to another drug?
The labels contraindicate a prior serious hypersensitivity reaction to the specific medicine and its excipients. A reaction to an unrelated drug is not listed as a contraindication in the passages we reviewed, so tell your prescriber about any allergy history and let them decide.
What should I do if I have swelling or trouble breathing after a dose?
Treat it as an emergency and seek medical attention immediately. The Zepbound and Foundayo labels tell patients to promptly seek medical attention and discontinue the medicine, and the other labels instruct clinicians to discontinue and treat promptly.
Is an itchy lump at the injection site an allergy?
It can be a local injection-site reaction, which the Zepbound label reports in 6% to 8% of patients at the 5, 10 and 15 mg doses versus 2% on placebo. Whether it is something more is a clinical judgment, so mention it to your prescriber.
If I reacted to one GLP-1, can I try another?
Wegovy, Ozempic and Mounjaro advise caution and say it is unknown whether such patients are predisposed. That decision belongs with your prescriber.
Are tablets different from injections on this?
The Foundayo and Wegovy tablet labels carry the same kind of contraindication and warning. Neither tablet label reviewed suggests the risk is absent.
Sources
- Novo Nordisk, Wegovy (semaglutide) injection and tablets prescribing information, revised 06/2026, checked 12 October 2026.
- Novo Nordisk, Ozempic (semaglutide) injection prescribing information, checked 12 October 2026.
- Eli Lilly and Company, Mounjaro (tirzepatide) prescribing information, revised 08/2026, checked 12 October 2026.
- Eli Lilly and Company, Zepbound (tirzepatide) prescribing information, revised 08/2026, checked 12 October 2026.
- Eli Lilly and Company, Foundayo (orforglipron) tablets prescribing information, revised 07/2026, checked 12 October 2026.
Medical disclaimer. This article is informational, was prepared by the GLP-1.Reviews editorial team from the public sources listed above, and is not medical advice. Label wording can change; confirm the instructions for your product with the Medication Guide that came with it. Talk to your prescriber or pharmacist about your own treatment, and see our medical disclaimer and editorial standards.
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