Does Evening Primrose Oil (EPO) cause menstrual irregularities, specifically dysmenorrhea or oligomenorrhea?

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From the Guidelines

Evening primrose oil is unlikely to cause menstrual irregularities, and its use may even help manage menstrual symptoms in some individuals. The evidence from various studies, including those on its anti-inflammatory properties and effects on hormonal balance, suggests that evening primrose oil does not have a significant impact on menstrual cycles [ 1 ].

Key Points to Consider

  • Evening primrose oil contains gamma-linolenic acid (GLA), an omega-6 fatty acid that may influence prostaglandin production and help regulate hormonal balance.
  • Typical dosages range from 500-1000 mg taken 1-3 times daily, though there is no standardized recommended dose.
  • While most women don't experience menstrual changes when taking evening primrose oil, individual responses can vary, and some may notice subtle changes in their cycle.
  • Significant disruptions in menstrual cycles are uncommon, and if experienced, may be related to other factors rather than the evening primrose oil itself [ 1 ].

Precautions and Considerations

  • Individuals taking blood-thinning medications should exercise caution when using evening primrose oil, as it may increase bleeding risk.
  • If new menstrual irregularities are experienced after starting evening primrose oil, it is recommended to discontinue use and consult with a healthcare provider to rule out other underlying causes.

From the Research

Menstrual Irregularities and Evening Primrose Oil

  • The relationship between evening primrose oil (EPO) and menstrual irregularities has been explored in several studies, with some indicating potential benefits in regulating menstrual cycles 2.
  • A 2024 study published in the Avicenna journal of phytomedicine found that EPO administration for 12 weeks in young women with polycystic ovary syndrome (PCOS) regulated irregular menstrual cycles and improved hormonal irregularities 2.
  • However, other studies have reported mixed results, with some finding no significant difference in menstrual symptoms between EPO and placebo groups 3.
  • A 1983 study published in The Journal of reproductive medicine suggested that EPO may be effective in treating premenstrual syndrome symptoms, including menstrual irregularities, due to its essential fatty acid content 4.
  • Another study published in 2009 in American family physician noted that while EPO is often used for women's health conditions, including menstrual symptoms, there is insufficient evidence to make a reliable assessment of its effectiveness for most clinical indications 5.
  • A 2024 systematic review and meta-analysis published in the Journal of menopausal medicine found that EPO did not show significant benefits in alleviating hot flashes compared to placebo or other interventions, but the severity of hot flashes was lower when EPO was administered for less than 6 months 6.

Key Findings

  • EPO may regulate irregular menstrual cycles in women with PCOS 2.
  • EPO has been found to improve hormonal irregularities in women with PCOS 2.
  • The evidence for EPO's effectiveness in treating premenstrual syndrome symptoms, including menstrual irregularities, is mixed 4, 3.
  • More research is needed to provide sufficient evidence for the use of EPO in alleviating menstrual irregularities and other women's health conditions 5, 6.

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

Evening primrose oil and treatment of premenstrual syndrome.

The Medical journal of Australia, 1990

Research

Evening primrose oil.

American family physician, 2009

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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