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Tirzepatide–oral contraceptive interaction — DFSRH MCQ

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HardEndocrinologyTirzepatide–oral contraceptive interactionDFSRH

A 38-year-old woman with type 2 diabetes and obesity (BMI 36 kg/m²) uses a desogestrel progestogen-only pill. She takes it consistently within the permitted window and has no other medication interaction or medical contraindication to its use. Twelve weeks ago, her diabetes team started once-weekly tirzepatide. The dose was increased every 4 weeks, and she is due to increase from 7.5 mg to 10 mg today. She has experienced no vomiting or diarrhoea. Pregnancy is reasonably excluded, and she has not had sexual intercourse during the preceding 21 days. She declines an implant, intrauterine contraception and injectable contraception but wishes to continue tirzepatide and her current pill. Which contraceptive advice is most appropriate?

Educational content. Not a substitute for clinical judgement or local policy.

Reveal the answer and explanation

Correct answer: E — Continue the pill and use a barrier method or abstain for 4 weeks after today’s increase and after each future dose increase

Explanation lettering: D = shown as A · A = shown as C · E = shown as D · C = shown as E

FSRH advises users of tirzepatide and oral contraception to switch to a non-oral method or add a barrier method for 4 weeks after initiation and for 4 weeks after every dose increase. Because she declines non-oral contraception, she may continue desogestrel but should use a barrier method or abstain for 4 weeks from today; the precaution must be repeated after any subsequent escalation. Tirzepatide delays gastric emptying and has reduced oral contraceptive peak concentration and overall exposure in pharmacokinetic studies. This precaution applies even without vomiting or diarrhoea, so A is incorrect. Gastrointestinal illness would create an additional absorption problem requiring the relevant missed-pill advice. B overlooks that each dose escalation starts a new 4-week precautionary interval. D is unnecessarily restrictive: guidance specifies discrete 4-week periods rather than uninterrupted additional precautions throughout an extended titration programme. E is incorrect because oral contraception is not contraindicated; switching to a non-oral method and adding temporary barrier contraception are alternative strategies. Emergency contraception is not indicated because there has been no intercourse during the potentially affected interval. The underlying evidence is limited and pharmacokinetic rather than based on observed contraceptive failure rates, but the UK specialty recommendation is explicit.

Reference: FSRH statement: Glucagon-like peptide-1 (GLP-1) agonists and oral contraception (January 2025) — https://www.fsrh.org/Common/Uploaded%20files/documents/CEU-statement-GLP-1-agonists-and-contraception.pdf Mounjaro KwikPen 5 mg solution for injection in pre-filled pen: Summary of Product Characteristics (9 April 2026) — https://www.medicines.org.uk/emc/product/15482/smpc