FAQ · GLP-1 · Editorial commentary

What does the published guidance say about Mounjaro and contraception?

Editorial commentary on the published Patient Information Leaflet and Summary of Product Characteristics. The MHRA-approved PIL for Mounjaro (tirzepatide) notes that tirzepatide slows gastric emptying, which may reduce the absorption of oral medicines including oral contraceptives. The PIL discusses non-oral contraceptive options and additional precautions following dose escalation. The published documents describe what the manufacturer and regulator have stated. Whether and how this applies to a specific person, and what contraceptive method is appropriate, is a decision between that person, their UK-licensed prescriber, and their sexual and reproductive health clinician. This page does not constitute clinical advice.

Decisions about contraception while taking a prescription GLP-1 are between you and your UK-licensed prescriber. Your GP, sexual and reproductive health clinician, or contraception nurse is the right point of contact. Notes below are editorial commentary on the published PIL and SmPC.

What the published mechanism describes

Published pharmacology for tirzepatide describes slowed gastric emptying as a known effect of dual GIP and GLP-1 receptor agonism. The SmPC notes that this slowed gastric emptying may reduce the absorption of orally administered medicines. The effect is most pronounced in the period following each dose, and the published guidance reports it as being more marked after dose escalation than at a stable maintenance dose.

What the Lilly PIL reports

The MHRA-approved Patient Information Leaflet for Mounjaro documents that patients using combined oral contraceptives may wish to consider a non-oral alternative or to add a barrier method, and references the period following dose escalation as the window during which absorption changes are most relevant. The exact wording, including the duration referenced, is set out in the PIL supplied with the medication and published on emc.medicines.org.uk. Patients are directed there for the authoritative text rather than relying on third-party summaries.

Non-oral contraceptive options listed in NHS contraception guidance

NHS contraception guidance lists non-oral methods that do not depend on gastric absorption. These include intrauterine devices (copper and hormonal IUS), the contraceptive implant, the contraceptive injection, the contraceptive patch, the vaginal ring, and barrier methods. Editorial note only: which method is suitable for an individual is a clinical decision made with a contraception provider, not something a comparison website can recommend.

Why the Wegovy PIL differs

Wegovy (semaglutide) is a GLP-1 receptor agonist. Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist. The published PILs differ in the prominence and specificity of the oral contraceptive note. Semaglutide also slows gastric emptying, and the Wegovy SmPC notes the same general interaction principle for orally administered medicines, though the wording differs. Patients comparing the two medications should read both PILs in full and discuss with their prescriber.

Where to ask

· The Patient Information Leaflet supplied in the medication box, or the version published on emc.medicines.org.uk.
· Your prescriber: GP, private clinic prescriber, or pharmacist prescriber.
· Your NHS sexual and reproductive health clinic, or NHS contraception guidance.
· Adverse effects can be reported via MHRA Yellow Card.

Decision routing: contraception choice is a clinical decision between you, your prescriber, and your contraception provider. This page is editorial commentary on published guidance.