Compilation of herbal plants (description, geographical distribution, taxonomy, line drawings), biodiversity and herbarium.

Read More
Research & Publication

Description of herbal and T&CM research, searchable publication and process from medicinal plant discovery to clinical trial in producing a high-quality registered herbal drug.

Read More
Traditional & Complementary Medicine (T&CM)


Definition and description of therapies, policy, training and education, research in the practise of (T&CM) and integrated medicine system.           

Read More


News Update

Announcement & Advertisement

Forthcoming Events

Annual Congress on Traditional Medicine

From Wed, 12. May 2021 Until Thu, 13. May 2021

5th International Conference on Medical and Health Informatics (ICMHI 2021

From Fri, 14. May 2021 Until Sun, 16. May 2021

International Conference on Traditional Medicine and Phytochemistry 2021

From Mon, 12. July 2021 Until Wed, 14. July 2021

Asian Symposium on Medicinal Plants and Spices XVII (2020)

From Tue, 17. August 2021 Until Thu, 19. August 2021

Evening Primrose

Plant Part Used

Seed oil


The potential benefits of evening primrose oil lie in its supply of omega-6 fatty acids—one of two essential fatty acids the body does not produce on its own. This essential nutrient, in conjunction with omega-3 fatty acid, plays a variety of important roles in the body. Both are needed for building cell membranes and providing the building blocks for hormones. The need for evening primrose oil in the modern diet has never been more pressing. By some estimates, as many as 90 percent of Americans may be deficient in essential fatty acids. Such a deficiency may play an important role in the cause of potentially fatal diseases.

Interactions and Depletions


Dosage Info

Dosage Range

500mg-8 grams (standardized extract) daily.

Most Common Dosage

1500mg (standardized extract) daily.


[span class=doc]Standardization represents the complete body of information and controls that serve to enhance the batch to batch consistency of a botanical product, including but not limited to the presence of a marker compound at a defined level or within a defined range.[/span]

The most current available medical and scientific literature indicates that this dietary supplement should be standardized to 8% GLA (gamma-linolenic acid) content per dose; expeller pressing is preferred.

Reported Uses

Omega-6 fatty acids like those found in evening primrose oil can play a crucial role in nerve function and in the prevention of diabetic neuropathy. (1) , (2) This positive effect on diabetic neuropathy is reported to be due to a decrease in some of the circulatory problems associated with diabetes. (3) , (4) , (5) Evening primrose was found to improve the symptoms of neuropathy without affecting the glucose control. (6) Consult a doctor who is familiar with alternative therapies for more information on the uses of evening primrose and other essential fatty acids in patients with diabetes.

Evening primrose has shown promise in the treatment of PMS symptoms,including irritable bowel syndrome related to menstruation and menopausal complaints. (7) , (8) , (9) Researchers think this is related to evening primrose’s ability to stimulate hormone production. Evening primrose was reported safe and effective in relieving problems associated with breast pain and tenderness. (10)

A study evaluated the use of gamolenic acid for the relief of menopause associated flushing and sweating. The treatment group received evening primrose oil as the source of gamolenic acid and vitamin E. This group was compared to a placebo group. Although there was a reduction in the maximum number of night time flushes, the study concluded that overall, gamolenic acid was no better than placebo in treating menopausal flushing. (11)

There is some belief that essential fatty acids may play a role in Sjogren's syndrome and other similar or related disorders. Medical trials evaluating the supplementation of gamma-linolenic acid (GLA) in the form of evening primrose oil in primary Sjogren's syndrome and systemic sclerosis have had positive results. (12) , (13) , (14) However, another trial found no significant improvement in any of the symptoms studied. (15)

The use of evening primrose oil and its component gamma-linolenic acid has been studied in schizophrenic patients by several groups. (16) , (17) It is believed that the symptoms of schizophrenia may be improved with the use of this supplement. Unfortunately, further research needs to be performed in this area.

Essential fatty acid supplementation may be of benefit in individuals suffering from chronic viral infections such as chronic fatigue syndrome, (18) , (19) , (20) although conflicting results have been published. (21)

There has also been some interest in the use of evening primrose oil for people with attention deficit/hyperactivity disorder (ADHD). (22) However, the evening primrose oil benefit was evident only in individuals with low zinc levels. Studies have demonstrated the ability of evening primrose oil to improve low zinc status, (23) thus it is believed that the ADHD benefit is likely due to this effect. (24) , (25)

Evening primrose oil may also be effective in reducing the disabling effects, number of relapses, severity, and duration of relapses in patients with multiple sclerosis. (26) Finally, fatty acids such as those found in evening primrose oil are effective in the management of arthritis and other inflammatory conditions. (27) , (28) , (29)

Toxicities & Precautions


[span class=alert]Be sure to tell your pharmacist, doctor, or other health care providers about any dietary supplements you are taking. There may be a potential for interactions or side effects.[/span]


This dietary supplement is considered safe when used in accordance with proper dosing guidelines.

If you are planning to have any type of surgery or dental work, stop using this dietary supplement for at least 14 days prior to the procedure.

Health Conditions

If you have epilepsy, do not use this dietary supplement. (30) If you have a bleeding disorder talk to your doctor before taking this dietary supplement. (31)

Side Effects

Side effects are possible with any dietary supplement. This dietary supplement may cause slight nausea, indigestion and loose stools if taken in large doses. A dosage reduction may be necessary. Tell your doctor if these side effects become severe or do not go away.

Pregnancy/ Breast Feeding

To date, the medical literature has not reported any adverse effects related to fetal development during pregnancy or to infants who are breast-fed. Yet little is known about the use of this dietary supplement while pregnant or breast-feeding. Therefore, it is recommended that you inform your healthcare practitioner of any dietary supplements you are using while pregnant or breast-feeding.

Age Limitations

To date, the medical literature has not reported any adverse effects specifically related to the use of this dietary supplement in children. Since young children may have undiagnosed allergies or medical conditions, this dietary supplement should not be used in children under 10 years of age unless recommended by a physician.


  1. View Abstract: Cameron NE, et al. Metabolic and Vascular Factors in the Pathogenesis of Diabetic Neuropathy. Diabetes. 1997;46 (Supp 2):S31-S37.
  2. Jamal GA, et al. Gamma-Linolenic Acid in Diabetic Neuropathy. Lancet. May1986:1098.
  3. View Abstract: Horrobin DF. The Effects of Gamma-linolenic Acid on Breast Pain and Diabetic Neuropathy: Possible Non-eicosanoid Mechanisms. Prostaglandins Leukot Essent Fatty Acids. Jan1993;48(1):101-4.
  4. View Abstract: Keen H, et al. Treatment of Diabetic Neuropathy with Gamma-linolenic Acid. The gamma-Linolenic Acid Multicenter Trial Group. Diabetes Care. Jan1993;16(1):8-15.
  5. View Abstract: Jack AM, Keegan A, Cotter MA, Cameron NE. Effects of diabetes and evening primrose oil treatment on responses of aorta, corpus cavernosum and mesenteric vasculature in rats. Life Sci. Sep2002;71(16):1863-77.
  6. View Abstract: Halat KM, Dennehy CE. Botanicals and dietary supplements in diabetic peripheral neuropathy. J Am Board Fam Pract. Jan2003;16(1):47-57.
  7. View Abstract: Horrobin DF. The Role of Essential Fatty Acids and Prostaglandins in the Premenstrual Syndrome. J Reprod Med. 1983;28:465-68.
  8. View Abstract: Budeiri D, et al. Is Evening Primrose Oil of Value in the Treatment of Premenstrual Syndrome? Control Clin Trials. 1996;17(1):60-68.
  9. View Abstract: Khoo SK, et al. Evening Primrose Oil and Treatment of Premenstrual Syndrome. Med J Aust. 1990;153(4):189-92.
  10. View Abstract: Pye JK, et al. Clinical Experience of Drug Treatments for Mastalgia. Lancet. Aug1985;2(8451):373-77.
  11. View Abstract: Chenoy R, Hussain S, Tayob Y, O'Brien PM, Moss MY, Morse PF. Effect of oral gamolenic acid from evening primrose oil on menopausal flushing. BMJ. Feb1994;308(6927):501-3.
  12. View Abstract: Horrobin DF. Essential Fatty Acid Metabolism in Diseases of Connective Tissue with Special Reference to Scleroderma and to Sjogren's Syndrome. Med Hypotheses. Jul1984;14(3):233-47.
  13. View Abstract: McKendry RJ. Treatment of Sjogren's Syndrome with Essential Fatty Acids, Pyridoxine and Vitamin C. Prostaglandins Leukot Med. Apr1982;8(4):403-8.
  14. View Abstract: Horrobin DF. Essential Fatty Acid and Prostaglandin Metabolism in Sjogren's Syndrome, Systemic Sclerosis and Rheumatoid Arthritis. Scand J Rheumatol Suppl. 1986;61:242-5.
  15. View Abstract: Oxholm P, Manthorpe R, Prause JU, et al. Patients with Primary Sjogren's Syndrome Treated for Two Months with Evening Primrose Oil. Scand J Rheumatol. 1986;15(2):103-8.
  16. View Abstract: Horrobin DF. The Relationship between Schizophrenia and Essential Fatty Acid and Eicosanoid Metabolism. Prostaglandins Leukot Essent Fatty Acids. May1992;46(1):71-7.
  17. View Abstract: Vaddadi KS. Use of Gamma-linolenic Acid in the Treatment of Schizophrenia and Tardive Dyskinesia. Prostaglandins Leukot Essent Fatty Acids. May1992;46(1):67-70.
  18. View Abstract: Behan PO, Behan WMH, Horrobin D. The effect of high doses of essential fatty acids in the post-viral fatigue syndrome. Acta Neurol Scand 1990;82:209-16.
  19. Chilton SA. Cognitive Behaviour Therapy for the Chronic Fatigue Syndrome. Evening Primrose Oil and Magnesium have been Shown to be Effective. BMJ. Apr1996;312(7038):1096.
  20. Lewith G. Chronic fatigue syndrome. Update 1995;50:765.
  21. View Abstract: Warren G, McKendrick M, Peet M. The Role of Essential Fatty Acids in Chronic Fatigue Syndrome. A Case-controlled Study of Red-cell Membrane Essential Fatty Acids (EFA) and a Placebo-controlled Treatment Study with High Dose of EFA. Acta Neurol Scand. Feb1999;99(2):112-6.
  22. View Abstract: Arnold LE, Pinkham SM, Votolato N. Does Zinc Moderate Essential Fatty Acid and Amphetamine Treatment of Attention-deficit/hyperactivity Disorder? J Child Adolesc Psychopharmacol. 2000;10(2):111-7.
  23. View Abstract: Dib A, et al. Effects of Gamma-linolenic Acid Supplementation on Pregnant Rats Fed a Zinc-deficient Diet. Ann Nutr Meta. 1987;31(5):312-19.
  24. View Abstract: Barr CL, Wigg KG, Feng Y, et al. Attention-deficit Hyperactivity Disorder and the Gene for the Dopamine D5 Receptor. Mol Psychiatry. Sep2000;5(5):548-51.
  25. View Abstract: Sunohara GA, Roberts W, Malone M, et al. Linkage of the Dopamine D4 Receptor Gene and Attention deficit/hyperactivity Disorder. J Am Acad Child Adolesc Psychiatry. Dec2000;39(12):1537-42.
  26. View Abstract: Dworkin RH, et al. Linoleic Acid and Multiple Sclerosis: A Reanalysis of Three Double-blind Trials. Neurology. Nov1984;34(11):1441-45.
  27. View Abstract: Belch JJ, Hill A. Evening Primrose Oil and Borage Oil in Rheumatologic Conditions. Am J Clin Nutr. Jan2000;71(1 Suppl):352S-6S.
  28. View Abstract: Leventhal LJ, Boyce EG, Zurier RB. Treatment of Rheumatoid Arthritis with Gammalinolenic Acid. Ann Intern Med. Nov1993;119(9):867-73.
  29. Joe LA, Hart LL. Evening Primrose Oil in Rheumatoid Arthritis. Ann Pharmacother. Dec1993;27(12):1475-7.
  30. View Abstract: Dines KC, et al. Nerve Function in Galactosaemic Rats: Effects of Evening Primrose Oil and Doxazosin. Eur J Pharmacol. 1995;281(3):303-09.
  31. PDR for Herbal Medicines, 2nd ed. Montvale, NJ: Medical Economics Company; 2000:299.










Explore Further

Consumer Data

Consumer data including medicinal herbs, dietary supplement monographs, health condition monographs and interactions and depletions.                                    

Read More
Professional Data

Professional data organized into medicinal herbs, dietary supplement monographs, health condition monographs, T&CM herbs, formulas, health conditions, interactions and depletions.

Read More
International Data

We offer International linkages to provide extensive content pertaining to many facets of T&CM as well as Integrated Medicine. Please register for access.    

Read More