Evening Primrose Oil (GLA)
Oenothera biennis
Popular eczema remedy that high-quality trials don't support
Mixed evidence
✨Joint & Skin
Evidence tier
Mixed
Research weight
Citations
16 verified / 16
Classification
Joint & Skin
❝
What the evidence says. Conflicting results across studies; benefit uncertain.
What is Evening Primrose Oil (GLA)?
Evening Primrose Oil (GLA) (Oenothera biennis) is a joint and skin supplement used for traditionally used for eczema (not supported). NutriDex grades the human evidence as Mixed. Evening primrose oil is a seed oil rich in the omega-6 fatty acid gamma-linolenic acid (GLA), long marketed for eczema on the theory that atopic skin has reduced delta-6-desaturase activity. Despite its popularity, the definitive 2013 Cochrane review of 27 RCTs (1,596 participants) concluded oral evening primrose oil and borage oil are not effective for eczema. Some smaller trials and mechanistic studies report benefit, but they are small, often open-label, and limited in quality. The overall evidence for skin claims is weak and conflicting rather than supportive.
Purported Benefits
✓Traditionally used for eczema (not supported)
✓May modestly raise skin GLA/DGLA
✓Also taken for PMS/breast tenderness (weak evidence)
Evidence by outcome
The same supplement can be well-proven for one use and unproven for another — here is the human evidence graded outcome by outcome.
| Outcome | Evidence | Effect | Studies |
|---|---|---|---|
| Eczema/atopic dermatitisCochrane review of 27 RCTs and pooled analyses show no benefit over placebo for eczema. | Strong | — no effect · negligible | 3 |
| Mastalgia (breast pain)Meta-analysis of 13 RCTs found EPO no better than placebo for breast pain. | Moderate | — no effect · negligible | 1 |
| Menopausal hot flashesOne meta-analysis cut severity under 6 months; another found frequency/intensity non-significant. | Mixed | ↔ mixed · small | 2 |
| Diabetic neuropathic pain (GLA)A small RCT and noninferiority trial vs alpha-lipoic acid favor GLA; short and small. | Preliminary | ↑ benefit · moderate | 2 |
| Rheumatoid arthritis pain (GLA)Cochrane found GLA reduced pain/stiffness but with more adverse events; low-quality evidence. | Preliminary | ↑ benefit · small | 1 |
| Raised skin/plasma GLA-DGLAOpen-label pilot linked plasma GLA rise to SCORAD drop, but no placebo control. | Preliminary | ↑ benefit · small | 1 |
Dosing & Compounds
Typical Dose
Commonly 4–6 g oil/day (~320–480 mg GLA).
Active Compounds
Safety & Cautions
Generally well tolerated; mild, temporary GI upset is most common. GLA can affect platelet function, so it may increase bleeding risk and potentiate warfarin/antiplatelet drugs — caution before surgery. Older reports suggest it may lower the seizure threshold (caution in epilepsy or with phenothiazines). Not a replacement for proven eczema therapy. Educational only — always check with your doctor or pharmacist before combining Evening Primrose Oil (GLA) with any medicine.
Key Studies ★ 16 studies
systematic review
Sharifi 2024 (systematic review)
✓ PubMed
Systematic review of clinical trials on EPO across inflammatory disorders found some signal in atopic eczema, menopausal hot flashes, mastalgia and diabetes, but highly heterogeneous evidence and no strong recommendation of efficacy; ineffective for PMS, psoriasis, acne, hand dermatitis and others.
meta-analysis
JMM 2024 (meta-analysis)
✓ Full text
Systematic review and meta-analysis of RCTs found EPO modestly lowered hot-flash severity when used under 6 months versus placebo, but showed no significant effect on hot-flash frequency or duration in menopausal women.
Systematic review
Sharifi 2024
✓ Full text
Systematic review of clinical trials on Oenothera biennis (evening primrose) oil across inflammatory diseases (including atopic dermatitis and rheumatoid arthritis) found the literature highly heterogeneous and unable to support a strong recommendation for efficacy.
Meta-analysis
Prado 2024
✓ PubMed
Systematic review and network meta-analysis (11 studies) ranking alpha-lipoic acid versus gamma-linolenic acid for diabetic peripheral neuropathy; ALA 600 mg/day lowered Total Symptom Score by ~1.05 points, with GLA evidence weaker and sparser.
Meta-analysis
Larki 2025
✓ PubMed
Systematic review/meta-analysis of 6 RCTs (450 women) on menopausal symptoms. EPO reduced hot-flash frequency by a mean of 2.13/day vs control but this was NOT statistically significant; intensity reduced by 0.19 (also non-significant); a significant reduction in hot-flash duration was seen. Evidence graded moderate-to-low. DOI: https://doi.org/10.34172/jcs.025.33570
meta-analysis
Ahmad Adni 2021 (meta-analysis)
✓ PubMed
Meta-analysis of 13 RCTs (1,752 patients): EPO was no better than placebo or other treatments (danazol, topical NSAIDs, vitamin E) for reducing mastalgia, with no difference in pain relief or adverse events.
systematic review/meta-analysis
Mahboubi 2021 (meta-analysis)
✓ PubMed
Systematic review and meta-analysis (six studies; four pooled) found oral evening primrose oil produced no significant improvement in cervical ripening (Bishop score; SMD 0.27, 95% CI -0.41 to 0.96, p=0.43) for labor induction, with very high heterogeneity.
Systematic review
Bamford 2013 (Cochrane)
✓ PubMed
Systematic review of 27 RCTs (1,596 participants); oral evening primrose oil and borage oil were no more effective than placebo for eczema.
systematic review (Cochrane)
Cameron 2011 (Cochrane)
✓ PubMed
Cochrane systematic review of herbal therapy for rheumatoid arthritis: in higher-quality studies, gamma-linolenic acid (from evening primrose, borage or blackcurrant seed oil) reduced pain, joint tenderness and morning stiffness versus placebo, but with more adverse events (about 20% vs 3%) and low-quality evidence overall.
Meta-analysis
van Gool 2004
✓ PubMed
Meta-analysis of placebo-controlled trials in atopic dermatitis. Pooled effect size of GLA supplementation on overall AD severity (11 trials) was only 0.15 (95% CL -0.02 to 0.32), not statistically significant; no benefit on itch, scaling, or lichenification. Concluded essential fatty acid supplementation has no clinically relevant effect on AD severity. DOI: https://doi.org/10.1111/j.0007-0963.2004.05851.x
RCT
Gholami 2025 (RCT)
✓ PubMed
4-week double-blind RCT in 66 patients with painful diabetic neuropathy: EPO 1,000 mg reduced neuropathic pain more than placebo, with twice-daily dosing outperforming once-daily dosing.
RCT
Breast cancer RCT 2023
✓ Full text
Parallel, randomized, double-blind, placebo-controlled 12-week trial (n=32) in breast cancer patients on chemotherapy: combined fish oil plus evening primrose oil improved fatty-acid profiles and decreased inflammatory markers such as IL-6.
randomized controlled trial
Won 2020 (RCT)
✓ Source
12-week double-blind noninferiority RCT (100 enrolled, 73 completed) in painful diabetic peripheral neuropathy: gamma-linolenic acid from evening primrose oil (320 mg/day GLA) was noninferior to alpha-lipoic acid for reducing pain intensity on VAS, with both treatments well tolerated.
RCT
Senapati 2008 (RCT)
✓ PubMed
Small randomized placebo-controlled trial (50 patients); 96% of the EPO group vs 32% of placebo improved over 5 months — but the study was tiny and limited in quality.
Open-label pilot
Simon 2014 (open pilot)
✓ Full text
Open-label pilot (21 patients): the rise in plasma GLA inversely correlated with SCORAD reduction, but with no placebo comparison.
government/authoritative body
NCCIH (NIH)
✓ Source
The US National Center for Complementary and Integrative Health concludes there is not enough evidence to support evening primrose oil for any health condition; oral EPO has not been shown to relieve atopic dermatitis and is probably no more effective than placebo for breast pain, while it is probably safe for most adults (mainly mild GI side effects).