GLP-1 drug interactions, as the labels state them

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.

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 in September 2026 — 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, worded slightly differently: “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 with ZEPBOUND and for 4 weeks after each dose escalation.”

The two are materially identical: a comma, and the drug name sitting in a different clause. Neither label states a different interval or a different route.

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.”

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

Related: the contraindications and the boxed warning, read from the same four documents.

See the providers

An interaction is a fact about the drug and your other medications. The boards list the providers who prescribe it, with what each one publishes about price, pharmacy and cancellation.

• Semaglutide providersprovider board

  Readers who have settled on semaglutide and are choosing who to buy it from.

• Tirzepatide providersprovider board

  Readers who have settled on tirzepatide and are choosing who to buy it from.

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, diarrhea 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.