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Tirzepatide-associated reduction in oral contraceptive bioavailability — DFSRH MCQ

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EasyMalabsorptionTirzepatide-associated reduction in oral contraceptive bioavailabilityDFSRH

A 32-year-old woman with a BMI of 34 kg/m² uses a desogestrel progestogen-only pill consistently and has had no recent missed pills. She is about to start tirzepatide 2.5 mg once weekly for weight management, with planned dose escalation after 4 weeks. She has no vomiting or diarrhoea and wishes to continue her pill rather than change to a non-oral contraceptive method. What additional contraceptive advice is most appropriate?

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

Reveal the answer and explanation

Correct answer: D — Use condoms for 4 weeks after starting tirzepatide and for 4 weeks after each dose increase

Explanation lettering: C = shown as B · D = shown as C · B = shown as D

Tirzepatide delays gastric emptying and is the GLP-1–based treatment for which a clinically significant reduction in oral contraceptive bioavailability has been identified. This concern applies to oral contraception, including the desogestrel pill, and is greatest when tirzepatide is initiated and after dose escalation. Because she declines a non-oral method, she should add condoms for 4 weeks after the first dose and for 4 weeks after every subsequent dose increase. A is inappropriate because tirzepatide-specific precautions are advised even without vomiting or diarrhoea; gastrointestinal symptoms would create an additional reason to follow missed-pill guidance. C omits protection after dose escalation, when the effect on gastric emptying and oral drug absorption may recur. D overlooks the corresponding risk during treatment initiation. E is unnecessarily prolonged: additional precautions are not routinely required throughout stable-dose treatment or after discontinuation for contraceptive absorption purposes. The separate recommendation to discontinue tirzepatide before a planned pregnancy concerns fetal exposure and drug elimination, not continued impairment of pill absorption after treatment has stopped. The supporting evidence is pharmacokinetic rather than contraceptive-outcome evidence, but current FSRH guidance and the UK product information give the same precautionary recommendation.

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 Summary of Product Characteristics (16 April 2026) — https://www.medicines.org.uk/emc/product/15482/smpc