Evening primrose oil
Summary
Evening primrose oil supplies gamma-linolenic acid, an omega-6 fat. A Cochrane review of 19 trials found it did not improve eczema, and a meta-analysis of 13 trials found no more breast-pain relief than placebo. NCCIH says there is not enough evidence for any condition. It is usually well tolerated; one study found it may increase bleeding with warfarin.
Key facts
- Oil from evening primrose seeds, containing omega-6 fatty acids including gamma-linolenic acid (GLA)[1]
- Cochrane, 19 EPO trials: no improvement in global eczema symptoms versus placebo as rated by patients or doctors[2]
- 13 trials (1,752 women): pain relief no different from placebo, topical NSAIDs, danazol or vitamin E[3]
- NCCIH: not enough evidence to support evening primrose oil for any health condition[1]
- 2 graded human outcomes on this page
- October 11, 2026
How it works
ProposedGLA is an omega-6 fatty acid proposed to influence inflammatory signalling; trials in eczema and breast pain did not show clinical benefit.[2]
What the human research says
Human trials only, one row per outcome. The form column shows what each trial actually tested. Grades follow our evidence-grading policy.
At a glance: strongest evidence per outcome
| Outcome | Grade | Effect | Strongest evidence | Rows |
|---|---|---|---|---|
| Breast pain | No effect | No effect | Meta-analysis of 13 trials · n = 1,752 · 2021 | 1 row |
| Eczema | No effect | No effect | Systematic review of 8 trials · n = 289 · 2013 | 1 row |
Every graded row
| Outcome | Effect | Grade | Best evidence | PMID |
|---|---|---|---|---|
| Cyclical breast pain (mastalgia) | No effect | No effect | Meta-analysis · n = 1,752 · 2021 Women with mastalgia in 13 randomized trials Form: Evening primrose oil · Dose: Varied across trials · Duration: Varied across trials The share of women with pain relief did not differ from placebo or from topical NSAIDs, danazol or vitamin E; adverse events were similar to placebo. | 34200727 (opens PubMed)Source [3] |
| Global eczema symptoms | No effect | No effect | Systematic review · n = 289 · 2013 Children and adults with atopic eczema (doctor-rated outcome, 8 trials) Form: Oral evening primrose oil · Dose: Varied across trials · Duration: Short-term trials Doctor-rated improvement did not differ from placebo (−3.26 on a 0–100 scale, 95% CI −6.96 to 0.45); patient-rated results were also null. The authors concluded EPO is not an effective eczema treatment. | 23633319 (opens PubMed)Source [2] |
Forms
Studied doses
Doses studied in human trials ranged from trial to trial in the pooled eczema and breast-pain studies, which the reviews cited here did not summarise as one range.[2][3]
Interactions
Published interactions only: each row cites a source. No row means none was found in our sources, not that a combination is safe.
Medicines
- WarfarinReviewOne study found evening primrose oil may increase bleeding in people taking warfarin.[2]
Who should be careful
- People taking warfarin
- A study cited by Cochrane found evening primrose oil may increase bleeding with warfarin.[2]
- Long-term use
- Trials were short; a case report raised possible inflammation, thrombosis and immune suppression with use beyond a year.[2]
- Pregnancy and breastfeeding
- NCCIH says it may be safe in pregnancy and breastfeeding, but the evidence is not conclusive.[1]
Talk to your pharmacist or clinician before starting a supplement, especially if you take prescription medicines.
Frequently asked questions
Does evening primrose oil help eczema?
No. A Cochrane review of 19 trials found it no better than placebo.[2]
Does evening primrose oil help breast pain?
A meta-analysis of 13 trials found pain relief no different from placebo.[3]
Is evening primrose oil safe?
It is usually well tolerated, with mild stomach effects, but it may raise bleeding risk with warfarin.[1][2]
Does it help menopause or PMS?
NCCIH says there is not enough evidence to know.[1]
Sources
- [1]Evening Primrose Oil (last updated November 2024). National Center for Complementary and Integrative Health, 2024. fact-sheet
- [2]Oral evening primrose oil and borage oil for eczema. Cochrane Database Syst Rev, 2013. systematic-review
- [3]A Systematic Review and Meta-Analysis of the Efficacy of Evening Primrose Oil for Mastalgia Treatment. Int J Environ Res Public Health, 2021. meta-analysis
What changed
- New monograph. Every PMID checked against NCBI E-utilities (title, journal and year from the PubMed record); each evidence row written from its abstract; intake and safety facts from the cited fact sheets.