About Evening Primrose

Wildflower taken mostly for breast pain, menopause symptoms, and to promote skin health.

Effectiveness Scores

Breast Pain Women: 6.0/10.
Evening primrose oil is rich in GLA, a fat the body uses to make compounds that calm swelling and sensitivity. The idea is that breast pain before a period might come from low GLA levels.
Why this rating: For decades, evening primrose oil was a go-to treatment for breast pain. In the UK it was even available by prescription. But when researchers tested it carefully against a placebo, women improved about the same either way. In 2002, the UK withdrew its prescription license for breast pain for the same reason it withdrew the eczema one: not enough evidence that it works. It's safe, so trying it isn't risky, but the relief many women notice seems to be the placebo effect.
Joint Pain Relief Rheumatoid arthritis: 4.0/10.
GLA can turn into compounds that calm swelling. That's the reason it's been tested for rheumatoid arthritis, where the joints stay inflamed.
Why this rating: Some studies found GLA eased joint pain and stiffness in people with rheumatoid arthritis. But many of the better studies used borage oil, which has more than twice as much GLA as evening primrose oil, and results were inconsistent. If you want to try GLA for joint pain, borage oil is closer to what was tested. Either way, it isn't a replacement for arthritis treatment.
Menopause Symptom Relief Menopausal women: 3.0/10.
The idea is that GLA may help the body regulate temperature and calm the hot flashes and night sweats that come with menopause.
Why this rating: Most controlled studies found evening primrose oil worked no better than a placebo for hot flashes. One small study found hot flashes got a little less severe, though not less frequent. Hot flashes are very sensitive to the placebo effect, which may be why so many users say it helped.
Skin Health Eczema: 1.0/10.
Evening primrose oil became popular for eczema because people with eczema often have low levels of GLA in their skin.
Why this rating: It's been tested thoroughly, and it doesn't work. A major review of 27 trials found no improvement in eczema compared to placebo. In 2002, the UK withdrew evening primrose oil's license as a prescription eczema treatment for this reason.

Understanding Effectiveness Scores

What does this mean?

Our effectiveness scoring system is based on scientific research and evidence. Each health outcome is rated on a scale of 1-10, with higher scores indicating stronger scientific support for the supplement's effectiveness.

1/10: Scientific evidence concludes that supplement is ineffective for purpose
2/10: No scientific evidence supports effectiveness
3/10: Inconclusive results regarding effectiveness
4/10: Minimal research on effectiveness
5/10: Limited evidence of effectiveness; may have potential benefits, but more research is needed
6/10: Some evidence supports the supplement's effectiveness, but research is mixed
7/10: Moderate evidence shows the supplement is effective for certain purposes, with limited population studies
8/10: Solid evidence suggests the supplement is effective, but research is not as extensive as higher levels
9/10: Strong scientific evidence supports the supplement's effectiveness, but some minor gaps in research remain (e.g., limited long-term studies or specific populations).
10/10: Ample scientific research demonstrates that the supplement is both highly effective and safe for long-term use.

Form Variations

Oil
About 8 to 10% GLA. The most popular GLA oil, and the one used in the breast pain and eczema research.
Best for: matching the breast pain and eczema research
Borage Oil
About 20 to 24% GLA, more than twice as much as evening primrose. Used in much of the rheumatoid arthritis research. Some borage products contain compounds that can harm the liver, so choose one labeled free of them (often "PA-free").
Best for: getting more GLA in fewer capsules
Blackcurrant Seed Oil
About 15 to 17% GLA, plus a small amount of an omega-3 fat. Less studied than the other two.
Best for: a middle option

Dosage & Timeline

Standard Dosages

Typical range: 1,000 to 3,000 mg a day
Breast pain studies: 2,000 to 3,000 mg a day

Check the label for GLA content. Evening primrose oil is usually 8 to 10% GLA.

Timeline to See Results

Menopause symptoms: studies ran for about 6 weeks
Breast pain: studies ran 3 to 6 months

All other outcomes may be noticed after extended use or lack sufficient studies to establish an effectiveness timeline.

Safety Information

Pregnancy and breastfeeding: Avoid. Some research has linked evening primrose oil to longer labor and more need for medical help during delivery. Some midwives recommend it late in pregnancy to prepare the cervix, but that should only happen under their care.
Hormonal conditions: Because of its impact on prostaglandin levels, individuals with hormone-sensitive conditions, such as breast cancer, ovarian cancer, or uterine cancer, should consult a healthcare provider before using evening primrose oil.
Blood pressure and blood thinners: Evening primrose oil may slow blood clotting slightly. If you take warfarin, aspirin, or another blood thinner, check with your doctor first.
Surgery: Due to its mild blood-thinning effects, it’s advisable to stop using evening primrose oil at least two weeks before any scheduled surgery.

Side Effects

Common side effects:

Mild stomach upset, nausea, or diarrhea
Headache, mostly when starting
Rare side effects:

Allergic skin reactions or itching
Easier bleeding, especially with blood thinners

Usage Information

People take evening primrose oil mostly for breast pain, menopause symptoms, PMS, and eczema. For most of these, the research hasn't found it works better than a placebo.

Evening primrose is a helper, not a treatment. It shouldn't replace care for breast pain, eczema, or arthritis.

User Experience

Gathered from reviews and forum posts, not from studies. What people report tells you what to expect. It does not tell you whether something works.

Most positive reviews are about menopause, with many people saying hot flashes and night sweats eased within days to weeks. Breast pain is another common success story, with some people saying the pain went away within a month.

That's a place where reviews and research disagree. In studies, women taking a placebo often improved just as much, which may explain why so many people believe it works.

On the negative side, some users report heart palpitations, memory problems, and confusion, mostly at higher doses. A few describe memory issues serious enough to see a doctor. Studies haven't found these effects, but they come up in reviews.

Alternative Names

EPO, Oenothera Biennis, King's Cure-All, German Rampion

Evening Primrose