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Epo4.5
Evening Primrose Oil Research
Likely helps
85 peer-reviewed studies
What the evidence says
Likely helps
Evening Primrose Oil appears to help in 4 of 5 studies with measurable effects — the evidence leans clearly favourable.
Most evidence is from high-quality meta-analyses and randomised trials published 1981–2026 with a typical study size of 84 participants.
Based on 85 studies · 15 meta-analyses · 50 RCTs · 9,950 total participants
Confidence
High confidence
What the studies found
4helped1unclear· 80 more without graded effect data
By outcome
Women's healthNot supported — systematic reviews find EPO no different from placebo for PMS · 1-3 cycles · No controlled evidence of effects on estrogen metabolism or hormone levels · 4-8 weeks · Not established for EPO alone; the only menopause trial used a four-herb blend · 4-8 weeks
Mostly mechanism / observational27 studies
Skin healthGLA may support the skin barrier/dryness; eczema evidence is weak · 12-16 weeks · Cochrane found oral EPO ineffective for eczema; acne evidence weak and adjuvant-only · 8-12 weeks
25 studies in the last 5 years · Latest meta-analysis: 2025
198120032026
1Meta-AnalysisCited 61×n=1,596 · large study2013
With regard to the risk of bias, the majority of studies were of low risk of bias; we judged 67% of the included studies as having low risk of bias for random sequence generation; 44%, for allocation concealment; 59%, for blinding; and 37%, for other biases.
Bamford JT et al. · The Cochrane database of systematic reviews (2013)
With regard to the risk of bias, the majority of studies were of low risk of bias; we judged 67% of the included studies as having low risk of bias for random sequence generation; 44%, for allocation concealment; 59%, for blinding; and 37%, for other biases.
Oral intake of EPO at a dose of ≤4 g/day significantly reduces serum TG levels and significantly increases HDL levels in hyperlipidemic subjects.
Khorshidi M et al. · Phytotherapy Research (2020)
EPO supplementation had no significant effect on TC, TG, LDL, and HDL.
However, in subgroup analysis, a significant reduction in TG at a dose of ≤4 g/day (weighted mean difference [WMD] = -37.28 mg/dl; 95% CI: -73.53 to -1.03, p = .044) and a significant increase in HDL in hyperlipidemic subjects (WMD = 5.468 mg/dl; 95% CI: 1.323 to 9.614, p = .010) was found.
A total of 926 articles were identified through database searching, of which, six RCTs were included in the meta-analysis.
Allergy published by European Academy of Allergy and Clinical Immunology and John Wiley & Sons Ltd.
Vassilopoulou E et al. · Allergy (2024)
A meta-analysis of 20 RCTs assessing probiotics, alone or combined with prebiotics, revealed a significant reduction in SCORAD scores, suggesting a consistent trend in alleviating AD symptoms in children without food allergies.
The review encompassed 27 RCTs examining prebiotics, Vitamin D, evening primrose oil, and substituting cow's milk formula with partially hydrolyzed whey milk formula.
Nonetheless, evidence for other dietary interventions remains limited, underscoring the necessity for well-designed intervention studies targeting multiple factors to understand etiological interactions and propose reliable manipulation strategies.
Some evidence regarding the potential benefits of EPO in inflammatory disorders were reported however caution is due to the limitations of the current survey.
Sharifi M et al. · BMC complementary medicine and therapies (2024)
In rheumatoid arthritis, mixed results were observed, with some studies reporting significant improvements in symptoms while others found no significant impact.
Some evidence regarding the potential benefits of EPO in inflammatory disorders were reported however caution is due to the limitations of the current survey.
Overall, contemporary literature is highly heterogeneous and fails to provide strong recommendations regarding the efficacy of EPO on inflammatory disorders.
15Systematic ReviewCited 40×n=400 · medium study2011
On the contrary, neither evening primrose oil nor St. John's Wort show an effect different than placebo.
Dante G, Facchinetti F · Journal of Psychosomatic Obstetrics & Gynecology (2011)
On the contrary, neither evening primrose oil nor St. John's Wort show an effect different than placebo.
Vitex agnus castus was the more investigated remedy and it was reported to consistently ameliorate PMS better than placebo.
None of the herbs was associated with major health risks, although the reduced number of tested patients does not allow definitive conclusions on safety.
16Total Symptom Score improvement in diabetic neuropathyMeta-AnalysisCited 6×n=11 · very small study2024
ALA and GLA appear to be safe and efficacious biofactors for improvement of DN symptoms.
Prado MB Jr et al. · Canadian journal of diabetes (2024)
Huge benefit
← WorseNo effectBetter →
Likely real
Eight of the 11 articles (73%) reported significant benefit of ALA vs placebo.
In the meta-analysis, the Total Symptom Score (TSS) for ALA 600 mg/day (ALA600) was 1.05 points lower (standard mean difference [SMD] -1.05, 95% confidence interval [CI] -2.07 to -0.04, p=0.04, I2=98.18%) compared with control at the end of the study.
In the network meta-analysis, ALA600 (SMD -1.68, 95% CI -2.8 to -0.6) and GLA (SMD -2.39, 95% CI -4.3 to -0.5) had significantly lower TSSs compared with placebo.
In this systematic review we present information relating to the effectiveness and safety of the following interventions: antibiotics, bromocriptine, combined oral contraceptive pill, danazol, diuretics, evening primrose oil, gestrinone, gonadorelin analogues, hormone replacement therapy (HRT), lisuride, low-fat diet, progestogens, pyridoxine, tamoxifen, tibolone, topical or oral non-steroidal anti-inflammatory drugs (NSAIDs), toremifene, and vitamin E.
In this systematic review we present information relating to the effectiveness and safety of the following interventions: anticonvulsants, antihypertensive drugs, antioxidants, antiplatelet drugs, atenolol, bed rest, hospital admission, or day care, calcium supplementation, choice of analgesia during labour, early delivery (interventionist care), evening primrose oil, fish oil, glyceryl trinitrate, magnesium supplementation, plasma volume expansion, and salt restriction.
20Atopic dermatitis severityMeta-Analysisn=3,763 · very large study2025
Nevertheless, larger, methodologically rigorous studies are essential to establish evidence for herbal remedies in atopic dermatitis treatment.
Anheyer M, Cramer H, Ostermann T, Anheyer D. · Dermatitis : contact, atopic, occupational, drug (2025)
No clear effect
← WorseNo effectBetter →
A meta-analysis on systemic used EPO, involving 13 RCTs, found no significant difference in atopic dermatitis severity compared with placebo (SMD: 0.14; 95% CI [-0.45; 0.73], 13 RCTs).
In conclusion, this review provides a nuanced perspective on herbal substance efficacy for atopic dermatitis.
While the EPO meta-analysis failed to show a discernible benefit beyond placebo, individual herbal preparations showed promising results in RCTs included in this review.