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Dietary supplement

Evening Primrose Oil 500 mg Ingredients & Drug Interactions

by NOW

Evening Primrose Oil 500 mg label
See full label image
Softgel Capsule Category: Fat/fatty Acid
Most serious interaction: Moderate
Clinical methodology reviewed by · Updated Sep 9, 2026 · Label data from the NIH DSLD
What is this page for?

First and foremost: checking Evening Primrose Oil 500 mg against your medications. The heart of this page is the interaction checker and the full interaction report — how this product’s ingredients may interact with prescription and over-the-counter medicines you may be taking.

Around that, we add a pharmacist’s high-level view of the product as a whole — what’s inside, the evidence for its stated use, how transparent the label is, and what safety data exists — so you can see the full picture in one place. It’s educational information from our licensed clinical databases and the clinical staff at HelloPharmacist — not medical advice — and we don’t sell or endorse products. Our editorial policy

The interaction bottom line Most serious interaction: Moderate

Evening Primrose Oil 500 mg is a dietary supplement by NOW with 1 active ingredient. Its ingredients are commonly taken for eczema and skin health, pms symptoms, breast pain (mastalgia).Based on those ingredients, 233 medications have a known interaction with it, the most serious rated moderate. The ingredients most likely to interact are Evening Primrose Seed Oil, Cold-Pressed. Use the checker below to test your specific medication, or read the full HelloPharmacist Interaction Report.

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Check Your Meds Against Evening Primrose Oil 500 mg by NOW

Ask about any prescription or over-the-counter medication and we check it for interactions with Evening Primrose Oil 500 mg by NOW — and tell you which ingredient is responsible.

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Computed from our clinical databases

HelloPharmacist Scorecard of Evening Primrose Oil 500 mg by NOW

Four independent checks of what is known — a summary of the available information, not a grade of the product itself.

Evidence for Intended Use
By FDA rules, dietary supplements can’t claim to treat, cure, or prevent disease — so labels speak in careful marketing language. We discern each product’s intended use from its name, label claims, and label statements, then grade the clinical evidence for that use. How these ratings are computed
Not assessable

None of the active ingredients could be matched to our evidence database, so the stated purpose can't be graded.

Why this rating?
  • The label markets this product for: women's health and healthy skin.
  • We looked for evidence on: Atopic dermatitis (eczema), Dry skin, Mastalgia, Menopausal symptoms, Premenstrual syndrome (PMS), Psoriasis — and 4 related terms.
  • We couldn't match any of the active ingredients to a HelloPharmacist monograph, so there's no evidence data to grade that purpose against.
Ingredient Transparency
Full

Every active ingredient lists its own amount on the label.

Why this rating?
  • The label discloses an exact amount for 3 of its 3 active ingredients.
  • “Evening Primrose Seed Oil, Cold-Pressed” is listed as a grouped ingredient — the label gives one combined amount (1.50 Gram(s)) without saying how much of each component you get.
Known Interaction Concern
Not assessable

None of the active ingredients could be matched to our interaction database.

Why this rating?
  • We couldn't match any ingredient to a HelloPharmacist monograph, so there was nothing to check interactions against.
Safety Information
Unable to assess

None of the active ingredients could be matched to our safety data.

Why this rating?
  • We couldn't match any ingredient to a HelloPharmacist monograph, so there was no safety data to measure.

HelloPharmacist summaryFully disclosed formula with no assessable stated purpose. Medication interactions could not be assessed, and safety information could not be assessed.

Assessment coverage: 0 of 3 active ingredients matched to our full ingredient reviews (monographs). Based on the product label dated Jul 25, 2024.

This Scorecard evaluates available label information, ingredient evidence, and known medication-safety considerations. It does not independently verify product identity, purity, potency, contamination, or manufacturing quality. How these ratings are computed

At a glance

General information

Key facts about Evening Primrose Oil 500 mg, straight from the product label.

Brand NOW
Barcode (UPC) 733739017529
Net contents 250 Softgel(s)
Market status On market
Date entered into DSLD Jul 25, 2024
DSLD ID 314307
Product type Fat/fatty Acid
Supplement form Softgel Capsule
Dietary claims / uses Nutrient, All Other, Structure/Function
Intended target group(s) Kosher, Adult Female (18 - 50 Years), Halal, Gluten Free, Dairy Free
From the label
Everything in this section is reproduced from the manufacturer’s own product label — it’s the label speaking, not HelloPharmacist. We show it so you can see exactly what the maker states; we don’t verify or endorse those statements.

Supplement Facts

The label details for Evening Primrose Oil 500 mg by NOW, sourced from the NIH Dietary Supplement Label Database.

Supplement Facts

Daily Value (DV) Target Group(s):
Adults and children 4 or more years of age
Minimum serving Sizes:
3 Softgel(s)
Maximum serving Sizes:
3 Softgel(s)
Servings per container
83
UPC/BARCODE
733739017529
IngredientAmount% DV
Calories15 Calorie(s)--
Total Fat1.5 Gram(s)2%
Polyunsaturated Fat1 Gram(s)--
Monounsaturated Fat0.5 Gram(s)--
Gamma-Linolenic Acid135 mg--
Evening Primrose Seed Oil, Cold-Pressed1.5 Gram(s)--

Other ingredients: Bovine Gelatin, Glycerin, Water

Tap any ingredient to jump to its full detail below.

Label statements
These statements are the manufacturer’s wording, reproduced from the product label — the label is saying it, not HelloPharmacist. We don’t verify or endorse them.
Suggested/Recommended/Usage/Directions

Suggested Usage: Take 3 softgels daily with food.

Formula

NOW Evening Primrose Oil has naturally occurring Gamma-Linolenic Acid (GLA), an Omega-6 fatty acid also found in Borage and Black Currant Seed Oils. Although the body can synthesize GLA from other dietary fats, it can be more efficiently utilized for bodily functions when consumed in its preformed state. By supporting the body’s healthy immune system responses, GLA may help to maintain normal skin barrier function, as well as a healthy vascular system.

Women's health

Triangle K (Kosher) Contains Gelatin

Triangle K (Kosher) Contains Gelatin

Crescent H (Halal)

FDA Disclaimer Statement

These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure or prevent any disease.

Precautions

Caution: For adults only. Keep out of reach of children.

Consult physician if pregnant/nursing, taking medication, or have a medical condition.

Not manufactured with yeast, wheat, gluten, soy, corn, milk, egg, fish, shellfish or sesame ingredients. Produced in a GMP facility that processes other ingredients containing these allergens.

Formulation

Natural color variation may occur in this product.

Healthy skin Balanced immune response

Non-GMO

Hexane-free

Made and quality tested in the USA with globally sourced ingredients.

Not manufactured with yeast, wheat, gluten, soy, corn, milk, egg, fish, shellfish or sesame ingredients.

FDA Statement of Identity

A Dietary Supplement

Seals/Symbols

Triangle K (Kosher) Contains Gelatin

Crescent H (Halal) GMP Quality Assured

General Statements

Nutritional Oils Family owned since 1968.

This bottle is made from 100% PCR (post-consumer recycled) resin.

Storage

Store in a cool, dry place after opening.

Is this label outdated? Report a formula or label change and our pharmacy team will review it.

See for yourself

Evening Primrose Oil 500 mg by NOW label

The label scan from the NIH Dietary Supplement Label Database. Tap to enlarge.

Evening Primrose Oil 500 mg label

Label images are published by the NIH Dietary Supplement Label Database for the version of this product on file. Always read your actual product label.

View the full label (PDF)
What’s inside

The Ingredients in Evening Primrose Oil 500 mg by NOW

This is the 1 active ingredient this product is made of. Select it to open its full monograph.

Serving size3 Softgel(s) Dosage formSoftgel Capsule Servings per container83 Amounts shown are per serving.

Evening Primrose Seed Oil, Cold-Pressed

Interacts with
233 drugs
1.5 Gram(s) per serving Form: Oenothera biennis Seed Oil, Cold-Pressed

Evening primrose oil is a seed oil rich in gamma-linolenic acid (GLA), an omega-6 fatty acid, that is popularly used for skin conditions, PMS, and bre...

Evening Primrose Seed Oil, Cold-Pressed monograph & interactions
  • › Gamma-Linolenic Acid

Other (inactive) ingredients: Bovine Gelatin, Glycerin, Water. These complete the product’s ingredient list but are not active constituents.

Interaction report

Evening Primrose Oil 500 mg by NOW Drug Interactions

Evening Primrose Oil 500 mg contains a single active ingredient, and it has known interactions with 233 medications. Here’s the picture, then you can look up your own drug.

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233Drugs
148 Moderate 85 Minor

Ingredients driving the most interactions

Evening Primrose Seed Oil, Cold-Pressed 233

Individual Drug Interactions

The ingredients in Evening Primrose Oil 500 mg interact with 233 drugs. Click any drug to see the details.

1 of the 1 ingredient in Evening Primrose Oil 500 mg interact with drugs. Each result below shows which ingredient is responsible. Evening Primrose Seed Oil, Cold-Pressed

Each ingredient & the kinds of drugs it affects

For each ingredient in Evening Primrose Oil 500 mg with known interactions, here are the types of medications it can affect. Open any type for the detail — or search your exact drug in the checker above.

Evening Primrose Seed Oil, Cold-Pressed5 drug types · 233 drugs

Anticoagulant/Antiplatelet Drugs

Theoretically, evening primrose oil may increase the risk of bleeding if used with anticoagulant or antiplatelet drugs.
Evening primrose oil contains gamma linolenic acid (GLA). There is preliminary clinical evidence that GLA can reduce platelet aggregation and prolong bleeding time.

Likelihood Possible Evidence D
Lithium

Theoretically, concomitant use of lithium with evening primrose oil might decrease lithium levels and effects.
In a case report, a patient on a stable dose of lithium for 10 years experienced a reduction in lithium levels after taking evening primrose oil 500 mg daily. Baseline levels were 0.69 mmol/L, which decreased to 0.37 mmol/L after 2 months and 0.23 mmol/L after 3 months of use. Lithium levels increased within 6 weeks of discontinuing evening primrose oil, to 0.73 mmol/L; no clinical effects were noted.

Likelihood Possible Evidence D
Lopinavir/Ritonavir (Kaletra)

Theoretically, evening primrose oil might increase the levels and effects of lopinavir.
In a case report, an HIV patient who took evening primrose oil (Efamol) along with lopinavir/ritonavir experienced an increase in serum levels of lopinavir to 15.2 mg/L. Six weeks after discontinuing evening primrose oil, levels of lopinavir returned to the normal range of 5-10 mg/L. When re-challenged with evening primrose oil for a week, the patient's lopinavir levels increased from 6.69 to 8.11 mg/L. It is suspected that evening primrose oil increases levels of lopinavir by inhibiting cytochrome P450 3A4 (CYP3A4), which metabolizes lopinavir. However, this effect has not been reported in other research.

Likelihood Possible Evidence D
Phenothiazines

Theoretically, taking evening primrose oil with phenothiazines might increase the risk of convulsions.
Evening primrose oil contains gamma-linolenic acid (GLA). There is some concern that taking supplements containing GLA might cause seizures, or lower the seizure threshold, when taken with phenothiazines. In one report, three patients with schizophrenia who had received phenothiazines developed EEG changes suggestive of temporal lobe epilepsy after starting treatment with GLA, although none experienced an actual seizure. In another report, two patients with schizophrenia who were stabilized on phenothiazines developed seizures when evening primrose oil 4 grams daily was added. One of these patients had a prior history of seizures. It is unclear whether evening primrose oil had any additive epileptogenic effects with the phenothiazines; there is no evidence that taking evening primrose oil alone causes seizures.

Likelihood Possible Evidence D
Cytochrome P450 2C9 (Cyp2C9) Substrates

Theoretically, evening primrose may increase the levels and clinical effects of CYP2C9 substrates.
In vitro research shows that linoleic acid, a constituent of evening primrose oil, inhibits CYP2C9.

Likelihood Possible Evidence D
Evening Primrose Seed Oil, Cold-Pressed full monograph & interactions
The maker

Brand information

Manufacturer and brand details for Evening Primrose Oil 500 mg, from the product label.

NOW

See all NOW products
Name
NOW FOODS
Street Address
395 S. Glen Ellyn Rd.
City
Bloomingdale
State
IL
ZipCode
60108
Web Address
nowfoods.com
Pharmacist Counseling Corner

Evening Primrose Oil 500 mg by NOW: Common Questions

Does Evening Primrose Oil 500 mg by NOW interact with any medications?
Yes. Based on its ingredients, Evening Primrose Oil 500 mg has a known interaction with 233 medications. Use the checker to see how it interacts with a specific drug.
How can one product interact with so many drugs?
Evening Primrose Oil 500 mg contains a single active ingredient, and that one ingredient can interact with many different medications on its own. We check it against each medication and show the mechanism responsible.
Where does this information come from?
The product label data comes from the NIH Dietary Supplement Label Database (DSLD); the interaction data is built on the Natural Medicines database and reviewed by HelloPharmacist pharmacists.

Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy

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Label information is sourced from the NIH Dietary Supplement Label Database and reflects the product version on file; always read your actual product label. This page is for education only and is not a substitute for professional medical advice. Confirm with your pharmacist or doctor before combining supplements and medications.

Evening Primrose Oil 500 mg label
Go deeper

The Full Monographs Behind Evening Primrose Oil 500 mg’s Ingredients

Every ingredient we hold a full HelloPharmacist monograph for — uses, evidence, safety, and the complete interaction list.

Herb & supplement monograph

Evening Primrose

Interacts with 233 drugs

Evening primrose oil is a seed oil rich in gamma-linolenic acid (GLA), an omega-6 fatty acid, that is popularly used for skin conditions, PMS, and breast pain. The evidence behind most of th...

Read the full Evening Primrose monograph →
Sources

Sources & How We Checked

Evening Primrose Oil 500 mg's label data comes from the NIH Dietary Supplement Label Database; the ingredient interaction data is from the Natural Medicines database, reviewed by our pharmacists.

Content is written and reviewed by licensed HelloPharmacist pharmacists. See our data sources and editorial standards for how this information is built and checked.

The 33 references behind this product’s interaction data

Every citation that drives the interaction findings for this product’s ingredients, from the evidence-graded Natural Medicines (TRC Healthcare) database. Open an ingredient to browse its citations — links open the study on PubMed or the publisher’s site.

Evening Primrose 33 references
  1. Shaw D, Leon C, Kolev S, Murray V. Traditional remedies and food supplements: a 5-year toxicological study (1991-1995). Drug Saf 1997;17:342-56.
  2. Laivuori H, Hovatta O, Viinikka L, et al. Dietary supplementation with primrose oil or fish oil does not change urinary excretion of prostacyclin and thromboxane metabolites in pre-eclamptic women. Prostaglandins Leukot Essent Fatty Acids 1993;49:691-4. PubMed
  3. Dove D, Johnson P. Oral evening primrose oil: its effect on length of pregnancy and selected intrapartum outcomes in low-risk nulliparous women (abstract). J Nurse Midwifery 1999;44:320-4. PubMed
  4. Guivernau M, Meza N, Barja P, Roman O. Clinical and experimental study on the long-term effect of dietary gamma-linolenic acid on plasma lipids, platelet aggregation, thromboxane formation, and prostacyclin production. Prostaglandins Leukot Essent Fatty A PubMed
  5. Cant A, Shay J, Horrobin DF. The effect of maternal supplementation with linoleic and gamma- linolenic acids on the fat composition and content of human milk: a placebo-controlled trial. J Nutr Sci Vitaminol (Tokyo) 1991;37:573-9. PubMed
  6. Keen H, Payan J, Allawi J, et al. Treatment of diabetic neuropathy with gamma-linolenic acid. The gamma-Linolenic Acid Multicenter Trial Group. Diabetes Care 1993;16:8-15.
  7. Blommers J, de Lange-De Klerk ES, Kuik DJ, et al. Evening primrose oil and fish oil for severe chronic mastalgia: a randomized, double-blind, controlled trial. Am J Obstet Gynecol 2002;187:1389-94.. DOI
  8. Cheung KL. Management of cyclical mastalgia in oriental women: pioneer experience of using gamolenic acid (Efamast) in Asia. Aust N Z J Surg 1999;69:492-4..
  9. Das UN. The lipids that matter from infant nutrition to insulin resistance. Prostaglandins Leukot Essent Fatty Acids 2002;67:1-12. PubMed
  10. Wedig KE, Whitsett JA. Down the primrose path: petechiae in a neonate exposed to herbal remedy for parturition. J Pediatr 2008;152:140, 140.e1. PubMed
  11. Ty-Torredes KA. The effect of oral evening primrose oil on bishop score and cervical length amongst term gravidas. Am J Obstet Gynecol. 2006;195(6 Suppl 1):S30.
  12. Moodley J and Norman RJ. Attempts at dietary alteration of prostaglandin pathways in the management of pre-eclampsia. Prostaglandins Leukot Essent Fatty Acids 1989;37(3):145-147. PubMed
  13. Tong M. [Treatment of hyperlipemia with evening primrose oil capsules]. Zhong Xi Yi Jie He Za Zhi. 1988;8:469-71, 452-3.
  14. Holman CP and Bell AF. A trial of evening primrose oil in the treatment of chronic schizophrenia. J Orhtomolecular Psych 1983;12:302-304.
  15. Vaddadi KS. The use of gamma-linolenic acid and linoleic acid to differentiate between temporal lobe epilepsy and schizophrenia. Prostaglandins Med 1981;6(4):375-379. PubMed
  16. Zou L, Harkey MR, and Henderson GL. Effects of herbal components on cDNA-expressed cytochrome P450 enzyme catalytic activity. Life Sci 8-16-2002;71(13):1579-1589. PubMed
  17. Yoon, S., Lee, J., and Lee, S. The therapeutic effect of evening primrose oil in atopic dermatitis patients with dry scaly skin lesions is associated with the normalization of serum gamma-interferon levels. Skin Pharmacol Appl.Skin Physiol 2002;15(1):20- PubMed
  18. Bamford, J. T., Gibson, R. W., and Renier, C. M. Atopic eczema unresponsive to evening primrose oil (linoleic and gamma- linolenic acids). J Am.Acad.Dermatol. 1985;13(6):959-965.
  19. Preece PE, Hanslip JI Gilbert L. Evening primrose oil (Efamol) for mastalgia. In: Horrobin DF. Clinical Uses of Essential Fatty Acids . Montreal, Quebec: Eden;1982.
  20. Parveen, S. Sarwar G. Ali M. Channa G. A. Danazol versus oil of evening primrose in the treatment of mastalgia. Pakistan Journal of Surgery. 2007;23(1):10-13.
  21. Belch JJF, Shaw B, O'Dowd A, et al. Evening primrose oil (Efamol) as a treatment for cold-induced vasospasm (Raynaud's phenomenon). Prog Lipid Res 1986;25:335-40.
  22. Johnson, M., Ostlund, S., Fransson, G., Kadesjo, B., and Gillberg, C. Omega-3/omega-6 fatty acids for attention deficit hyperactivity disorder: a randomized placebo-controlled trial in children and adolescents. J.Atten.Disord. 2009;12(5):394-401. PubMed
  23. Farzaneh F, Fatehi S, Sohrabi MR, Alizadeh K. The effect of oral evening primrose oil on menopausal hot flashes: a randomized clinical trial. Arch Gynecol Obstet 2013;288(5):1075-9. PubMed
  24. Puri BK. The safety of evening primrose oil in epilepsy. Prostaglandins Leukotrienes Essential Fatty Acids 2007;77:101-3. PubMed
  25. Jalloh MA, Gregory PJ, Hein D, et al. Dietary supplement interactions with antiretrovirals: a systematic review. Int J STD AIDS. 2017 Jan;28(1):4-15. PubMed
  26. Osman M, Badawi E. Evening primrose oil reducing serum lithium concentration. Ther Adv Psychopharmacol. 2016 Oct;6(5):343-44. PubMed
  27. Kalati M, Kashanian M, Jahdi F, Naseri M, Haghani H, SHeikhansari N. Evening primrose oil and labour, is it effective? A randomized clinical trial. J Obstet Gynaecol. 2018 Feb 9:1-5.
  28. Sharif SN, Darsareh F. Impact of evening primrose oil consumption on psychological symptoms of postmenopausal women: a randomized double-blinded placebo-controlled clinical trial. Menopause. 2020;27(2):194-198. PubMed
  29. Shahraki AD, Mirhoseini S, Movahedi M, Hajihashemy M, Haghollahi F. Comparative 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;12:78. PubMed
  30. Shahinfar S, Abedi P, Jahanfar S, Khajehpoor M, Chashmyazdan M. The effect of evening primrose oil on cervical ripening and birth outcomes: A systematic review and meta-analysis. Heliyon 2023;9(2):e13414. PubMed
  31. Mahmoodinasab M, Loripoor M, Vazirinejad R, Aminzadeh F. Effect of misoprostol with and without evening primrose (Oenothera biennis) on induction of missed abortion. Avicenna J Phytomed 2023;13(5):454-462.
  32. Hashemi H, Hasanpoor-Azghady SB, Farahani M, Amiri-Farahani L. Comparison of the effect of vaginal misoprostol and evening primrose oil capsule with misoprostol alone on the consequences of abortion in women with intrauterine fetal death: a randomized cli
  33. Ariana S, Amjadi N, Kazemi SN, Ahmadli Z. The Use of Evening Primrose Oil for Cervical Ripening in Low-Risk Women with Term Pregnancy: A Randomized Double-Blinded Controlled Trial. Complement Med Res 2024;31(3):215-221. PubMed

See these in context on the Evening Primrose monograph →

Parts of this content are provided by the Therapeutic Research Center, LLC.

DISCLAIMER: Currently this does not check for drug-drug interactions. This is not an all-inclusive comprehensive list of potential interactions and is for informational purposes only. Not all interactions are known or well-reported in the scientific literature, and new interactions are continually being reported. Input is needed from a qualified healthcare provider including a pharmacist before starting any therapy. Application of clinical judgment is necessary.

© 2021 Therapeutic Research Center, LLC

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