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ingestible · for premenstrual syndrome

Evening Primrose Oil

Reviewed by the Nimbera editorial team · Last updated May 2026

Budeiri et al. systematic review of 7 placebo-controlled trials: the two most methodologically rigorous studies showed no beneficial effect; inconsistent scoring across trials prevented meta-analysis. Authors concluded EPO is of little value for PMS management. PMID 8721802.$12-$30 per month

How to use

If you choose to try it, take 2-4 g of evening primrose oil daily (standardised to at least 8% GLA) for at least 3 months. Take with meals to improve absorption. Results are uncertain.

How it works

Evening primrose oil is rich in gamma-linolenic acid (GLA), an omega-6 fatty acid that serves as a precursor to anti-inflammatory prostaglandin E1. The hypothesis is that PMS may relate to impaired GLA metabolism, but clinical evidence is weak.

Where to buy

Pharmacies and health food stores. Common brands include Efamol, Barleans, and Nature's Bounty. Choose cold-pressed, unrefined oil in dark capsules.

Typical cost: $12-$30 per month

Safety notes

May interact with blood thinners and anticoagulants. Avoid before surgery. May lower seizure threshold in people on phenothiazine antipsychotics. The clinical evidence for PMS is weak - manage expectations.

Drug & supplement interactions

  • Always tell your doctor or pharmacist about any supplements you take.
  • Interactions can occur with prescription medications, blood thinners, and immunosuppressants.
  • Herbal remedies can affect how the body absorbs or metabolises drugs.
  • Check drugs.com interactions checker before starting.

Clinical source

Budeiri et al., Is evening primrose oil of value in the treatment of premenstrual syndrome?, Control Clin Trials, 1996

This information is compiled from primary clinical literature and is for informational purposes only. It is not a substitute for professional medical advice. Read our full disclaimer.