Evening primrose oil (EPO)
Written by Fertility Decoded. Reviewed by D R, MS (OBG), FRM. Review date: 31 August 2026.
The verdict
No quality evidence it helps the fertility outcome it's marketed for (cervical mucus); a systematic review found real pregnancy-complication risk with oral use, which is exactly the scenario an unknowingly-pregnant TTC user could be in.
A plant-oil supplement, marketed specifically to TTC women as a way to improve cervical mucus around ovulation.
What the evidence shows
No high-quality trial evidence found that EPO improves cervical mucus or pregnancy rates — the claimed mechanism (GLA converting to prostaglandins) is plausible pharmacology, not demonstrated clinical benefit.
Evidence tier
Documented harm⛔ Peer-reviewed evidence of serious adverse effects from the item's own chemistry/pharmacology or a well-characterized allergic mechanism. More serious than contamination; not resolved by buying a 'reputable brand'.
Frequently asked questions
- No quality evidence supports the cervical-mucus or pregnancy-rate claim.
- A systematic review linked oral use in pregnancy to complications (premature rupture of membranes, more oxytocin augmentation) — a risk if you conceive and keep taking it. Standard advice is to stop at ovulation.
Does EPO improve cervical mucus or fertility?
Is EPO safe when trying to conceive?
Sources
Take this further
Sources last reviewed .