GLP-1 drug interactions, as the labels state them
Section 7 of a prescribing information document is short, and on these four labels it is almost the same section four times — with one difference that matters a great deal to some readers and appears on only half of them. What follows is what all four say, where they differ, and the census behind that claim.
Ellis Brandt built this site’s grading methodology and maintains it. Section 7 of all four labels read end to end. Last re-read 2026-09-04.
Not medical advice. Semaglutide and tirzepatide are prescription-only medicines, and whether one is appropriate for you is a question for a licensed clinician who knows your history. This page reports what the FDA-approved prescribing information says and nothing else; it is not written or reviewed by a clinician. See the medical disclaimer.
The census
| Labels read in full | 4 |
|---|---|
| Carrying an insulin warning | 4 |
| Carrying an oral-medication warning | 4 |
| Carrying an oral-contraceptive precaution | 2 |
Read 2026-09-04. ⛔ A count of four documents, not a claim about every GLP-1 ever approved.
Insulin and insulin secretagogues
All four labels carry this one, and all four give the same instruction: consider reducing the dose of the other drug when starting the GLP-1. Ozempic states the mechanism plainly — it “stimulates insulin release in the presence of elevated blood glucose concentrations”, and patients taking it with an insulin secretagogue such as a sulfonylurea, or with insulin, “may have an increased risk of hypoglycemia, including severe hypoglycemia.”
Wegovy states the same risk in its own terms: “WEGOVY lowers blood glucose and can cause hypoglycemia. The risk of hypoglycemia is increased when WEGOVY is used concomitantly with insulin or insulin secretagogues (e.g., sulfonylureas). The addition of WEGOVY in patients treated with insulin has not been evaluated.”
Oral medications
All four delay gastric emptying, and all four say that this can affect how an oral drug is absorbed. What they then advise is not identical, and the differences are worth reading rather than summarising into one sentence.
| Label | What section 7.2 advises |
|---|---|
| Ozempic | In clinical pharmacology trials semaglutide “did not affect the absorption of orally administered medications to any clinically relevant degree”; nonetheless caution should be exercised. |
| Wegovy | Monitor the effects of oral medications given alongside it, and consider increased clinical or laboratory monitoring for medications with a narrow therapeutic index or that require monitoring. The label reports one specific finding: in a drug interaction study with the semaglutide tablet, “levothyroxine exposure was increased 33% (90% CI: 1.25-1.42).” |
| Mounjaro | Exercise caution, and monitor patients on oral medications dependent on threshold concentrations for efficacy and those with a narrow therapeutic index, naming warfarin as the example. |
| Zepbound | Exercise caution, and monitor patients on oral medications dependent on threshold concentrations for efficacy and those with a narrow therapeutic index, naming warfarin as the example. |
Oral contraceptives — on two of these four labels
Both tirzepatide labels carry an explicit contraception precaution. Neither semaglutide label does. This is the single largest difference between the two molecules’ section 7, and it is stated here as a census of four documents read on 2026-09-04 — not as a claim about semaglutide in general.
Mounjaro, section 7.2: “Advise patients using oral hormonal contraceptives to switch to a non-oral contraceptive method or add a barrier method of contraception for 4 weeks after initiation and for 4 weeks after each dose escalation with MOUNJARO. Hormonal contraceptives that are not administered orally should not be affected”. Zepbound carries the same instruction in the same words.
The tirzepatide labels also explain why, in section 8.3: use of the drug “may reduce the efficacy of oral hormonal contraceptives due to delayed gastric emptying. This delay is largest after the first dose and diminishes over time.”
| Label | Active ingredient | Precaution in section 7 |
|---|---|---|
| Mounjaro | tirzepatide | Present — switch to a non-oral method or add a barrier method for 4 weeks |
| Zepbound | tirzepatide | Present — switch to a non-oral method or add a barrier method for 4 weeks |
| Ozempic | semaglutide | Not present in this label’s section 7 |
| Wegovy | semaglutide | Not present in this label’s section 7 |
Not an interaction, but on every label: surgery and sedation
All four labels carry a warning about general anaesthesia and deep sedation. It sits in section 5 rather than section 7, so it is not a drug interaction — but it is the thing a reader searching for interactions most often needs, and the labels are unusually candid about the limits of what is known.
Zepbound, section 5.9: there have been “rare postmarketing reports of pulmonary aspiration in patients receiving GLP-1 receptor agonists undergoing elective surgeries or procedures requiring general anesthesia or deep sedation who had residual gastric contents despite reported adherence to preoperative fasting recommendations.” The label then says that available data “are insufficient to inform recommendations to mitigate the risk”, including whether changing fasting instructions or pausing the drug would help, and instructs patients to tell their healthcare providers before any planned surgery or procedure that they are taking it.
⛔ That is the label declining to give a stopping interval, not this site failing to find one. Ozempic, Wegovy and Mounjaro carry the same warning under their own numbering.
Sources
| Label | Applicant on the label | SPL version | Label effective date | Where it was read |
|---|---|---|---|---|
| Ozempic (semaglutide) | Novo Nordisk Pharmaceutical Industries, LP | 20 | 2026-06-01 | DailyMed, set id adec4fd2-6858-4c99-91d4-531f5f2a2d79 |
| Wegovy (semaglutide) | Novo Nordisk Pharmaceutical Industries, LP | 19 | 2026-06-18 | DailyMed, set id ee06186f-2aa3-4990-a760-757579d8f77b |
| Mounjaro (tirzepatide) | Eli Lilly and Company | 40 | 2026-08-27 | DailyMed, set id d2d7da5d-ad07-4228-955f-cf7e355c8cc0 |
| Zepbound (tirzepatide) | Eli Lilly and Company | 40 | 2026-08-28 | DailyMed, set id 487cd7e7-434c-4925-99fa-aa80b1cc776b |
Each capture was checked against its own document title before anything was quoted from it, and a nonsense set id was fetched through the identical method in the same session as a control — it returned 404 with an empty body, so a document that returns is a document that exists.
Related: the contraindications and the boxed warning, read from the same four documents.
More, read from the same labels
- Semaglutide vs tirzepatidereading the label
What the four FDA-approved labels say each molecule is, what each is approved to treat, and where the two differ.
- Dose escalation schedulesreading the label
The starting dose, the escalation interval and the maximum dose each label sets, and why they are not interchangeable.
- Side effect ratesreading the label
What each label reports for nausea, vomiting, diarrhoea and constipation — and the sentence every label prints above those numbers.
- Missed dose rulesreading the label
The window each label gives for a late dose, and the minimum gap it requires when the injection day changes.
- Buying one onlinereading the label
The agency's own warning signs for a telehealth GLP-1 seller, its 28-day vial rule, and what it says about drugs that arrive warm.
- Who should not take onereading the label
The boxed warning every one of these labels carries, the two contraindications, and which warnings appear on which product.