Evening primrose oil supplement: what the evidence says before you buy
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- Evening primrose oil softgels with GLA listed. Best for: Adults who want to try EPO and compare products fairly. See options on Amazon
- Higher-strength 1,000 mg evening primrose oil. Best for: Adults who want fewer softgels per day. See options on Amazon
What evening primrose oil is
NCCIH describes evening primrose as a plant native to the Americas whose yellow flowers open at sunset. The oil from its seeds contains omega-6 fatty acids, including gamma-linolenic acid (GLA).
Today it is promoted for atopic dermatitis (a type of eczema), rheumatoid arthritis, premenstrual syndrome, breast pain, menopause symptoms and other conditions, and it is also used in skin products.
What the research shows
NCCIH says a substantial number of studies have looked at evening primrose oil for eczema, breast pain and starting labor, with less evidence for other uses. Its conclusion is that there is not enough evidence to support using it for any health condition.
| Use | What NCCIH reports |
|---|---|
| Eczema (atopic dermatitis) | Taken by mouth, not shown to help symptoms |
| Breast pain | Probably no more effective than placebo |
| Starting labor | Inconsistent results, oral or vaginal |
| PMS, menopause, rheumatoid arthritis | Insufficient evidence |
For menopause symptoms or PMS, talk with your clinician about options with stronger evidence.
Reading the label: oil vs GLA
The front label usually shows the oil per softgel, often 500 or 1,000 mg. GLA is the part being sold. As a label example, NOW Evening Primrose Oil lists a serving of 3 softgels supplying 1,500 mg of cold-pressed oil and 135 mg of GLA, taken daily with food.
Compare GLA per serving between products, and count the softgels it takes. The NOW softgel uses bovine gelatin; vegetarian buyers should look for plant-based softgels.
Safety and side effects
NCCIH says evening primrose oil is probably safe for most adults when taken by mouth and is generally well tolerated. The most common side effects are stomach symptoms such as abdominal pain, nausea and diarrhea. Less is known about safety in children.
NCCIH advises talking with your health care provider before using it if you take any medicine, because some herbs and medicines interact in harmful ways.
Pregnancy, labor and breastfeeding
NCCIH says evening primrose oil may be safe during pregnancy and breastfeeding, but the evidence is not conclusive. When used to try to start labor, reported side effects were mostly mild, but long-term safety for that use has not been established. Do not use it to start labor except under your clinician's direction.
Taking it while breastfeeding raises GLA in breast milk, which NCCIH says has not been linked to harm in infants.
How herbal supplements are regulated
NCCIH explains that many herbal products taken by mouth are marketed as dietary supplements, and the rules for making and selling supplements are less strict than those for drugs. FDA likewise says it does not approve dietary supplements for safety and effectiveness before they are marketed.
That means the label claims on an evening primrose oil bottle have not been reviewed the way a medicine's would be. It is one more reason to compare plain facts, such as GLA per serving and the ingredient list, rather than benefit claims, and to tell your health care providers about any herbal products you use so they can check for interactions.
How to choose, if you decide to try it
- Compare GLA per serving, not just oil.
- Check serving size; some products need 3 softgels a day.
- Choose cold-pressed, clearly labeled oil.
- Set a trial period and stop if nothing changes; NCCIH found no condition where evidence supports it.
- Look for a verifiable quality mark such as USP or NSF. FDA does not approve supplements for safety and effectiveness before sale.
What to look for when you buy
Evening primrose oil softgels with GLA listed
Best for: Adults who want to try EPO and compare products fairly
A label listing GLA per serving, like the 135 mg in the NOW example, lets you compare beyond the oil weight.
Watch out: Evidence does not support EPO for any condition, per NCCIH. Stomach upset is the most common side effect.
See options on AmazonHigher-strength 1,000 mg evening primrose oil
Best for: Adults who want fewer softgels per day
Larger softgels can reach a given GLA amount with fewer capsules. Check GLA per softgel.
Watch out: Bigger softgels can be harder to swallow. Ask your doctor first if you take medicines.
See options on AmazonQuestions people ask
- What is evening primrose oil supplement good for?
- It is promoted for eczema, breast pain, PMS and menopause, but NCCIH says there is not enough evidence to support it for any health condition.
- Can I take evening primrose oil with other supplements?
- Talk with your health care provider first if you take any medicine or other supplements, since some herbs and medicines interact in harmful ways.
- Is evening primrose oil safe?
- NCCIH says it is probably safe for most adults by mouth and generally well tolerated; less is known for children.
- Can evening primrose oil start labor?
- Studies have had inconsistent results and long-term safety is not established. Use it for labor only under your clinician's direction.
- Does evening primrose oil help eczema?
- NCCIH says evening primrose oil taken by mouth has not been shown to help atopic dermatitis symptoms. Talk with a dermatologist about treatments with stronger evidence.
- What is GLA in evening primrose oil?
- Gamma-linolenic acid, an omega-6 fatty acid in the seed oil. Labels may list it separately; one example lists 135 mg in a 3-softgel serving.
Sources
- Evening Primrose Oil: Usefulness and Safety (nccih.nih.gov), National Center for Complementary and Integrative Health
- Evening Primrose Oil 500 mg Softgels (www.nowfoods.com/products/supplements/evening-primrose-oil-500-mg-softgels), NOW Foods
- Information for Consumers on Using Dietary Supplements (fda.gov), U.S. Food and Drug Administration