Evening Primrose Oil

Last Updated: November 30, 2023

Evening primrose oil (EPO) is extracted from the seeds of the evening primrose plant and is primarily composed of the omega-6 fatty acids linoleic acid and gamma-linolenic acid. EPO may improve cervical readiness during childbirth, but most clinical trials have been small and there are safety concerns that must be considered.

Evening Primrose Oil is most often used for

What is evening primrose oil?

Evening primrose (Oenothera biennis) is a traditional medicinal herb native to North America that now grows in many places worldwide. The plant is suitably named for its yellow flowers that bloom in the evening after sunset.[3] Evening primrose oil (EPO) is extracted from the seeds of the evening primrose plant and is a rich source of omega-6 fatty acids, particularly linoleic acid (70–74%) and gamma-linolenic acid (GLA) (8–10%).[2] While the fatty acid profile of EPO is generally thought to be the main factor driving its effects in the body, EPO also contains other bioactive compounds, including triterpenes, phenolic acids, and tocopherols (vitamin E).[2] Despite being promoted as a remedy for a variety of ailments, most clinical research has not identified any clear benefits of EPO supplementation.

What are evening primrose oil’s main benefits?

EPO has been used to improve cervical ripening/softness in preparation for childbirth. Current research does suggest that EPO (particularly when given vaginally) may improve Bishop scores — the gold standard assessment tool for predicting the success of labor induction — and may have comparable effects to the medication misoprostol.[4][5][6][7] Some research has reported reductions in labor time and the rate of cesarean section with EPO use, but these findings are less consistent.[6] Currently, there is no established dosing and large clinical trials are needed to properly assess the safety and efficacy of EPO in this context. Potential side effects that have been reported will be discussed in the following section.

What are evening primrose oil’s main drawbacks?

EPO is generally safe and well-tolerated. The most common side effects include headache and gastrointestinal symptoms (e.g., heart burn, nausea, vomiting, diarrhea, abdominal pain, flatulence).[8][9] When used prior to childbirth, reported side effects include meconium-stained amniotic fluid, premature membrane rupture, and arrest of descent;[5] and in one case report, a woman using both EPO and raspberry leaf tea before labor gave birth to an infant with widespread bruising.[10]

EPO might increase the risk of bleeding, particularly if combined with other blood-thinning medications (e.g., warfarin).[11] Although evidence is limited, EPO may have an inhibitory effect on certain cytochrome P450 (CYP450) enzymes involved in drug metabolism, which could theoretically alter the efficacy or increase the risk of side effects with some medications; however, the clinical relevance of this is unclear.[12] In one case report, EPO administration seemed to increase blood levels of an anti-retroviral medication (lopinavir/ritonavir) used for managing HIV, and the proposed mechanism was CYP450 enzyme inhibition.[13]

Case reports have suggested that EPO may increase the risk of seizures.[14][15] In all cases, EPO was administered to people with schizophrenia along with phenothiazine drugs, which are known to increase the risk of seizures, and all of the individuals had a history of seizures or abnormal brain wave activity. However, the mechanism behind this is unclear, and animal research suggests that the primary fatty acids in EPO (linoleic acid and GLA) and their metabolites may instead be protective against seizures.[16][11]

How does evening primrose oil work?

The clinical effects of EPO are thought to be largely due to its content of the fatty acid GLA which can have immune-modulating and anti-inflammatory effects. While less thoroughly studied, EPO is also a source of polyphenols which likely contribute an anti-inflammatory and antioxidant benefit.[2] In the body, GLA is a precursor for dihomo-gamma-linolenic acid (DGLA), which can in turn be metabolized into eicosanoids with anti-inflammatory properties, such as prostaglandin E1.[17] Cervical ripening and labor induction during childbirth both depend on prostaglandins, and increased synthesis of prostaglandin E1 is thought to be the main mechanism by which EPO may increase cervical readiness.[1] Similarly, misoprostol, a medication that is used to prepare the cervix for labor induction, is a prostaglandin E1 analog.[18]

What else is Evening Primrose Oil known as?
Note that Evening Primrose Oil is also known as:
  • Oenothera biennis
  • King's cure-all
  • Fever-plant
  • Night willow herb
  • German rampion
Dosage information

EPO is available in both liquid and capsule form. In clinical trials, oral EPO dosages have generally ranged from 500 mg up to 6 grams daily. For cervical ripening, EPO capsules inserted vaginally appear to be most effective, and dosages of 1 to 4 grams daily are often used. Importantly, optimal dosing of EPO has not been established.[1][2]

The composition of EPO will vary depending on the growing environment and extraction methods used, which could result in varying effects of EPO depending on the preparation used. EPO is also prone to oxidation and should ideally be stored in a dark and tightly sealed container.[2]

Examine Database: Evening Primrose Oil
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References
  1. ^Hutcherson TC, Cieri-Hutcherson NE, Lycouras MM, Koehler D, Mortimer M, Schaefer CJ, Costa OS, Bohlmann AL, Singhal MKSystematic Review of Evening Primrose () Preparations for the Facilitation of Parturition.Pharmacy (Basel).(2022-Dec-10)
  2. ^Farag MA, Reda A, Nabil M, Elimam DM, Zayed AEvening primrose oil: a comprehensive review of its bioactives, extraction, analysis, oil quality, therapeutic merits, and safety.Food Funct.(2023-Sep-19)
  3. ^Kenda M, Glavač NK, Nagy M, Sollner Dolenc M, On Behalf Of The OemonomHerbal Products Used in Menopause and for Gynecological Disorders.Molecules.(2021-Dec-08)
  4. ^Wormer KC, Bauer A, Williford AEBishop ScoreStatPearls.(2023-01)
  5. ^Shahinfar S, Abedi P, Jahanfar S, Khajehpoor M, Chashmyazdan MThe effect of evening primrose oil on cervical ripening and birth outcomes: A systematic review and meta-analysis.Heliyon.(2023-Feb)
  6. ^Hemmatzadeh S, Mohammad Alizadeh Charandabi S, Veisy A, Mirghafourvand MEvening primrose oil for cervical ripening in term pregnancies: a systematic review and meta-analysis.J Complement Integr Med.(2023-Jun-01)
  7. ^Shahraki AD, Mirhoseini S, Movahedi M, Hajihashemy M, Haghollahi FComparative Study of the Effect of Vaginal use of Primrose Oil with Misoprostol on Cervical Preparation of Prim Gravid Women: A Double-blind Clinical Trial.Adv Biomed Res.(2023)
  8. ^Melainie Cameron, Joel J Gagnier, Sigrun ChrubasikHerbal therapy for treating rheumatoid arthritisCochrane Database Syst Rev.(2011 Feb 16)
  9. ^Bayles B, Usatine REvening primrose oil.Am Fam Physician.(2009-Dec-15)
  10. ^Wedig KE, Whitsett JADown the primrose path: petechiae in a neonate exposed to herbal remedy for parturition.J Pediatr.(2008-Jan)
  11. ^Bamford JT, Ray S, Musekiwa A, van Gool C, Humphreys R, Ernst EOral evening primrose oil and borage oil for eczema.Cochrane Database Syst Rev.(2013-Apr-30)
  12. ^Zou L, Harkey MR, Henderson GLEffects of herbal components on cDNA-expressed cytochrome P450 enzyme catalytic activity.Life Sci.(2002-Aug-16)
  13. ^Jalloh MA, Gregory PJ, Hein D, Risoldi Cochrane Z, Rodriguez ADietary supplement interactions with antiretrovirals: a systematic review.Int J STD AIDS.(2017-Jan)
  14. ^Vaddadi KSThe use of gamma-linolenic acid and linoleic acid to differentiate between temporal lobe epilepsy and schizophrenia.Prostaglandins Med.(1981-Apr)
  15. ^Holman C, Bell AA Trial of Evening Primrose Oil in the Treatment of Chronic SchizophreniaJ Orthomol Med.(1983)
  16. ^B K PuriThe safety of evening primrose oil in epilepsyProstaglandins Leukot Essent Fatty Acids.(2007 Aug)
  17. ^Timoszuk M, Bielawska K, Skrzydlewska EEvening Primrose () Biological Activity Dependent on Chemical Composition.Antioxidants (Basel).(2018-Aug-14)
  18. ^Bakker R, Pierce S, Myers DThe role of prostaglandins E1 and E2, dinoprostone, and misoprostol in cervical ripening and the induction of labor: a mechanistic approach.Arch Gynecol Obstet.(2017-Aug)
  19. ^Steckel L, Sosnoskie L, Steckel S Common evening-primrose (Oenothera biennis L.)Weed Technol.(2019 Jul)
  20. ^Horrobin DF, Manku MSPremenstrual syndrome and premenstrual breast pain (cyclical mastalgia): disorders of essential fatty acid (EFA) metabolism.Prostaglandins Leukot Essent Fatty Acids.(1989-Sep)
  21. ^Dante G, Facchinetti FHerbal treatments for alleviating premenstrual symptoms: a systematic review.J Psychosom Obstet Gynaecol.(2011-Mar)
  22. ^Whelan AM, Jurgens TM, Naylor HHerbs, vitamins and minerals in the treatment of premenstrual syndrome: a systematic review.Can J Clin Pharmacol.(2009)
  23. ^Ahmad Adni LL, Norhayati MN, Mohd Rosli RR, Muhammad JA Systematic Review and Meta-Analysis of the Efficacy of Evening Primrose Oil for Mastalgia Treatment.Int J Environ Res Public Health.(2021-Jun-10)
  24. ^Christelle K, Zulkfili M, Noor N, Draman NThe Effects of Evening-Primrose Oil on Menopausal Symptoms: A Systematic Review and Meta-analysis of Randomized Controlled TrialsCurr Womens Health Rev.(2020)
Examine Database References
  1. Eczema Symptoms - Bamford JT, Ray S, Musekiwa A, van Gool C, Humphreys R, Ernst EOral evening primrose oil and borage oil for eczema.Cochrane Database Syst Rev.(2013-Apr-30)
  2. Labor Duration (Pregnancy) - Hemmatzadeh S, Mohammad Alizadeh Charandabi S, Veisy A, Mirghafourvand MEvening primrose oil for cervical ripening in term pregnancies: a systematic review and meta-analysis.J Complement Integr Med.(2023-Jun-01)
  3. Labor Duration (Pregnancy) - Shahinfar S, Abedi P, Jahanfar S, Khajehpoor M, Chashmyazdan MThe effect of evening primrose oil on cervical ripening and birth outcomes: A systematic review and meta-analysis.Heliyon.(2023-Feb)
  4. Breast Tenderness - Ahmad Adni LL, Norhayati MN, Mohd Rosli RR, Muhammad JA Systematic Review and Meta-Analysis of the Efficacy of Evening Primrose Oil for Mastalgia Treatment.Int J Environ Res Public Health.(2021-Jun-10)
  5. Total cholesterol - Khorshidi M, Zarezadeh M, Moradi Moghaddam O, Emami MR, Kord-Varkaneh H, Mousavi SM, Alizadeh S, Heshmati J, Olang B, Aryaeian NEffect of evening primrose oil supplementation on lipid profile: A systematic review and meta-analysis of randomized clinical trials.Phytother Res.(2020-Oct)
  6. Hot Flash Symptoms - Christelle, K et al.The Effects of Evening-Primrose Oil on Menopausal Symptoms: A Systematic Review and Meta-analysis of Randomized Controlled TrialsCurr Womens Health Rev.(2020-07-01)