Supplements and Desogestrel.
Desogestrel, sold under the brand names Cerazette, Cerelle, Aizea, is a progestogen-only contraceptive.
Desogestrel is a progestogen-only contraceptive. It is used as an alternative to combined oral contraception in patients where oestrogen is contraindicated (breastfeeding, migraine with aura, VTE history, smokers over 35). Mechanism varies. The traditional pill in this class (norethisterone) thickens cervical mucus. Desogestrel additionally suppresses ovulation. The supplement surface is smaller than for combined oral contraceptives, but the St John's Wort interaction still applies and is flagged by the BNF. Enzyme induction can reduce contraceptive efficacy. Other supplement interactions are quieter at standard doses. The compliance issue specific to this class is the dosing window. 3 hours for the traditional pill, 12 hours for desogestrel. Supplement timing rarely affects this.
Below are the 2 documented pairs we have explicitly assessed against Desogestrel in the Distil database: 1 red and 1 amber. The pairs cluster around 2 mechanisms: CYP3A4 induction and Hormonal axis modulation. Every call is cited to either a clinical reference (PMID) or the British National Formulary. Anything not on this list is either still to be assessed or beyond our database scope. The checker beneath surfaces assessments by supplement, and the missing-item form at the bottom of the page routes any uncatalogued supplement into our next curation pass.
Documented interactions
CYP3A4 induction
St John's Wort can reduce the contraceptive reliability of the progestogen-only pill. Because there is no oestrogen backup in the progestogen-only pill, the consequence of reduced hormone levels is more direct. We treat this as a do-not-combine pair.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Hormonal axis modulation
Vitex (chasteberry) acts on hormone signals, lowering prolactin and gently nudging oestrogen and progesterone receptors in lab studies. The progestogen-only pill relies entirely on its progestogen, so in theory vitex could interfere with that balance. There is no study showing the pill fails when vitex is added, so this is a caution rather than a firm warning. If you take the progestogen-only pill, mention vitex to your prescriber before adding it, and treat any change in your bleeding pattern as a reason to check in.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
What this list does not say. Pairs not flagged here are not implicitly safe. They are either not yet in our database, or fall outside our inclusion scope (food-supplement interactions only; for drug-drug interactions, the BNF is authoritative). Use the checker below to surface any supplement, and submit a missing item if you take something we have not catalogued.
How we grade severity, choose what's in scope, and what we exclude.
Every call on this page is reasoned. We publish the full rubric for severity tiers, the medication inclusion logic, the evidence grades we accept, and what we deliberately leave out. About three thousand words. Worth reading once if you use this tool more than occasionally.
Read the full methodologyWant this checked across everything you take?
This page checks the pairs you enter. The personalised Distil report goes further:
- the same graded, cited interaction check across your whole stack, not just the pairs you thought to type in
- where your current routine may be leaving you short of your goals
- the evidence-backed compounds worth adding, and the ones worth dropping
It's a paid report: £79, or £49 for the first 25 customers. The interactions check is one section of it, and you can read a real one in full before you buy.
See a real sample reportSomething missing?
If a supplement or medication you take isn't in our autocomplete, tell us. We go through what people flag every week and add what's missing.