Fertility Decoded

Evening primrose oil (EPO)

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'.

Sources

Take this further

Last reviewed .