--- title: Evening Primrose Oil vs Fish Oil for PMS: Compared description: Evening primrose oil vs fish oil for PMS symptoms: compare the fatty acids, evidence and side effects before choosing one with your doctor today. url: https://niyora.com/treatments/evening-primrose-oil-vs-omega-3/ --- - [Niyora](https://niyora.com/) - [Treatments](https://niyora.com/treatments/) - Evening primrose oil vs fish oil for PMS Treatment # Evening primrose oil vs fish oil for PMS Evening primrose oil is an omega-6 supplement, while fish oil supplies omega-3 fatty acids. Trials on evening primrose oil for PMS mostly show no benefit over placebo, and the studies reviewed here don't test omega-3 for PMS specifically. Both are generally mild on side effects, so the real question is which one is worth discussing with your doctor. Updated 14 October 2026 Niyora editorial Mixed evidence Strength of evidence Mixed Trials disagree, or the effect is small. - None - Limited - Mixed - Moderate - Strong ## At a glance - Evening primrose oil is an omega-6 oil (mostly linoleic acid and gamma-linolenic acid); fish oil is an omega-3 oil (EPA and DHA) [4]. - The most rigorous evening primrose oil trials for PMS found no real difference from placebo [2] [3] [5]. - Larger, double-blind, placebo-controlled trials also reported much bigger improvements with evening primrose oil [7] [8], and the sources don't explain why results diverge so sharply. - Evening primrose oil's side effects are usually mild: nausea, headache and stomach upset [1]. - No trial reviewed here tested fish oil against placebo for PMS, so its premenstrual benefit isn't established in this evidence. ## Strength of evidence Mixed evidence - None - Limited - Mixed - Moderate - Strong Evening primrose oil's placebo-controlled crossover trials found no PMS benefit over placebo, while larger placebo-controlled trials reported bigger gains, so results are inconsistent [1] [2] [3] [5] [7] [8]. No trial here tested fish oil (omega-3) for PMS, so its benefit isn't established. Side by side Evening primrose oil and Fish oil (omega-3) What it's made from Evening primrose oil Seeds of Oenothera biennis [4] Fish oil (omega-3) Oily fish, such as salmon or mackerel Also compared in the table below - Main fatty acid type - PMS evidence in controlled trials - Evidence for breast pain (mastalgia) - Common side effects - Typical trial length before judging effect | Compared on | Evening primrose oil | Fish oil (omega-3) | | --- | --- | --- | | What it's made from | Seeds of Oenothera biennis [4] | Oily fish, such as salmon or mackerel | | Main fatty acid type | Omega-6: linoleic acid and GLA [4] | Omega-3: EPA and DHA | | PMS evidence in controlled trials | Best-controlled trials found no benefit over placebo [2] [3] [5] | Not tested for PMS in the sources used here | | Evidence for breast pain (mastalgia) | Some improvement reported over six months [6] | Not covered in these sources | | Common side effects | Nausea, headache, upset stomach [1] | Fishy aftertaste, burping, loose stools (general reports, not from these trials) | | Typical trial length before judging effect | 4 to 6 months in reviewed trials [4] | Not established in these sources | ## How do evening primrose oil and omega-3 differ? Evening primrose oil comes from the seeds of a yellow wildflower, Oenothera biennis. It's mostly linoleic acid and gamma-linolenic acid (GLA), both omega-6 fatty acids [4]. Fish oil is the common source of omega-3s: EPA and DHA, pulled from oily fish like salmon, mackerel or sardines. The two oils aren't variations on the same ingredient. They come from different fatty acid families entirely. That matters because omega-6 and omega-3 fats are processed through some of the same pathways in the body, which is part of why researchers test them separately rather than as one combined remedy. A quick side-by-side: - **Source:** evening primrose oil comes from wildflower seeds; fish oil comes from oily fish such as salmon or mackerel. - **Fatty acid family:** evening primrose oil is omega-6 (linoleic acid and GLA); fish oil is omega-3 (EPA and DHA) [4]. - **What switching gives you:** taking more evening primrose oil won't give you any omega-3s, and taking more fish oil won't give you any GLA. If you want the full picture on evening primrose oil on its own, [what evening primrose oil is and whether it helps PMS](https://niyora.com/treatments/evening-primrose-oil/) covers where it comes from and how it's typically used. ## Is evening primrose oil omega-3 or omega-6? Evening primrose oil is an omega-6 oil. It is not an omega-3 source, despite often being shelved next to fish oil in the supplement aisle. Its fatty acid makeup, from the clinical literature, breaks down roughly like this [4]: - Linoleic acid: about 60% to 80% of the oil - Gamma-linolenic acid (GLA): about 8% to 14% - Omega-3 fatty acids: not present in a meaningful amount GLA is the omega-6 fatty acid most of evening primrose oil's research has focused on [4]. Fish oil's EPA and DHA work through different anti-inflammatory routes. Neither fatty acid family is better in general. They're different tools, tested for different things, and the research record for PMS specifically leans almost entirely on the omega-6 side, since that's what evening primrose oil trials have studied. ## Which works better for PMS or PMDD? Most of the controlled research here is on evening primrose oil, and it isn't encouraging. The two best-designed trials, both randomized, double-blind and placebo-controlled, found no real difference between evening primrose oil and placebo for PMS symptoms [3] [5]. A systematic review of seven placebo-controlled trials concluded evening primrose oil is "of little value" for PMS, though the trials were small enough that a modest effect couldn't be fully ruled out [2]. A broader review of evening primrose oil across many inflammatory conditions reached the same conclusion for PMS specifically [1]. | Trial or review | What it found | Evidence strength | | --- | --- | --- | | Two placebo-controlled crossover trials [3] [5] | No real difference from placebo on PMS symptoms | Weak | | Systematic review of 7 trials [2] | EPO "of little value" for PMS | Weak | | Two Iranian trials, 2018 and 2019 [7] [8] | Reported significant drops in symptom severity with EPO | Mixed, larger sample sizes | | Review across inflammatory conditions [1] | EPO did not demonstrate effectiveness for PMS | Weak | Larger trials out of Hamadan University (120 and 80 participants) also used double-blind, placebo-controlled designs but reported much bigger drops in symptoms with evening primrose oil [7] [8]. Why these results diverge so sharply from the smaller, placebo-controlled crossover trials [3] [5] isn't explained in the sources. None of the trials reviewed here tested fish oil against placebo for PMS or PMDD, so there's no comparable evidence trail to weigh against it. For a closer look at the evidence for PMS and PMDD specifically, see [evening primrose oil for PMS](https://niyora.com/treatments/evening-primrose-oil-for-pms/). What the research says The two most rigorous trials used a placebo-controlled crossover design, which is good at ruling out expectation effects, and both came back negative for evening primrose oil [3] [5]. ## How do the side effects compare? Evening primrose oil is generally well tolerated. Across the trials reviewed, the side effects reported were mild [1]: - Nausea - Headache - Upset stomach or loose stools - Occasional mild skin reactions Fish oil's side effects aren't covered in the sources used for this page. Common reports describe a fishy aftertaste, burping or loose stools, usually eased by taking it with food. Neither oil has a side effect profile that should stop you from asking a doctor about either one. The bigger open question is effectiveness, not safety. For the fuller list of what evening primrose oil can cause, including effects on mood, see [evening primrose oil side effects](https://niyora.com/treatments/evening-primrose-oil-side-effects/). ## Can you switch from one to the other, or take both? No trial in this review tested evening primrose oil and fish oil together for PMS, so switching or combining them isn't something the evidence can guide directly. In practice, some people do take both, on the idea that balance between omega-6 and omega-3 matters more than either fatty acid alone. That idea is plausible, but it hasn't been tested for premenstrual symptoms in the trials cited here. If you're currently on evening primrose oil and it isn't helping after a few cycles, switching to fish oil isn't backed by PMS-specific evidence either. **Neither oil has a track record strong enough to promise a benefit if you switch.** Evening primrose oil's effects, when there are any, tend to show up slowly. One review found it should be used for four to six months before judging whether it helps [4]. For timing and dosing, [evening primrose oil dosage](https://niyora.com/treatments/evening-primrose-oil-dosage/) and [how long evening primrose oil takes to work](https://niyora.com/treatments/how-long-does-evening-primrose-oil-take-to-work/) go through what the trials used. ## Which should you ask your doctor about? Given the evidence, evening primrose oil is reasonable to mention to a doctor, but it shouldn't replace treatments with stronger backing, like certain SSRIs or hormonal contraceptives, which guidelines support for PMS and PMDD. A doctor can help you weigh it alongside those options. If your premenstrual symptoms are mild and mostly physical, like breast tenderness, evening primrose oil has slightly more support there than for mood symptoms [6]. If anger, sadness or anxiety are the main problem, the evidence for either oil is thin, and other approaches have more research behind them. See [PMS treatment that actually helps](https://niyora.com/treatments/pms-treatment/) for the fuller list. While you're figuring out what helps, Niyora is a PMS and PMDD support app. Its Moon feature can help you write down what happened in a hard moment, see it from another angle, and calm down before you decide what to say or do next. When to see a doctor If this takes a week of every month, or you have thoughts of hurting yourself, see a GP or gynecologist and bring two months of daily notes. From the research library ## Research on evening primrose oil 38 studies in the library look at evening primrose oil in PMS and PMDD. They were published from 1983 to 2026, and each one has a short summary of what was tested and found. 38 studies, 1983 to 2026 How strong the studies are Strong study design 4 Moderate study design 18 Early or limited evidence 16 - [Systematic review, 2009Which herbs, vitamins and minerals help treat PMS?Only calcium has good evidence to work for PMS. Chasteberry and vitamin B6 may help, but most of the 62 products people try lack proper research.Strong study design](https://niyora.com/research/papers/herbs-vitamins-and-minerals-in-the-treatment-of-premenstrual-syndrome-a-2009/) - [Systematic review, 2007What treatments work for premenstrual syndrome?Many treatments have been studied for PMS, but researchers face a major challenge: there is no standard way to measure symptom severity, making it difficult to know which treatments truly work.Strong study design](https://niyora.com/research/papers/premenstrual-syndrome-2007/) - [Study, 2002Which PMS treatments have good scientific evidence?Calcium at 1200 mg daily and certain antidepressants have good evidence of working. Many popular treatments like vitamin B6, evening primrose oil, and birth control pills lack strong evidence. Some treatments like progesterone do not work.Strong study design](https://niyora.com/research/papers/premenstrual-syndrome-evidence-based-treatment-in-family-practice-2002/) - [Randomised trial, 2000Which dietary supplements help PMS?Only calcium has strong evidence from large rigorous trials. Magnesium, vitamin E, and carbohydrate supplements show limited promise but need more research. Vitamin B6 and evening primrose oil have mixed results.Strong study design](https://niyora.com/research/papers/the-potential-for-dietary-supplements-to-reduce-premenstrual-syndrome-pms-2000/) - [Study, 2024Does a combination of evening primrose oil, tocotrienol, and vitamin B6 reduce premenstrual symptoms?Yes. In women with PMS taking this combination for 3 months, premenstrual symptoms improved significantly. The overall PMS score dropped by 61.03%, menstrual pain dropped by 75.20%, and breast tenderness dropped by 82.54%.Moderate study design](https://niyora.com/research/papers/a-real-world-study-to-evaluate-the-effectiveness-of-evening-primrose-oil-in-2024/) - [Randomised trial, 2024Does a herbal soft gel capsule with three oils reduce PMS symptoms?The capsule reduced women's PMS symptoms when compared to their baseline, but was not significantly better than taking sunflower oil.Moderate study design](https://niyora.com/research/papers/effects-of-the-herbal-soft-gel-capsule-containing-pimpinella-anisum-oenothera-2024/) [See all 38 studies on evening primrose oil](https://niyora.com/research/topics/treatment-evening-primrose/) ## Questions people ask Is evening primrose oil the same as omega-3? + No. Evening primrose oil is an omega-6 fatty acid source, mostly linoleic acid and gamma-linolenic acid (GLA) [4]. Omega-3s come from fish oil, as EPA and DHA. They're from different fatty acid families and aren't interchangeable, even though both get sold as PMS supplements. Does evening primrose oil work better than fish oil for PMS? + The trials reviewed here don't test fish oil against evening primrose oil directly for PMS. Evening primrose oil's own evidence is weak, with the best-controlled trials showing no benefit over placebo [2] [3] [5], and fish oil wasn't covered in the PMS-specific studies used here. Can I take evening primrose oil and fish oil together? + You can, but no trial reviewed here tested the combination for PMS. Some people take both for general omega-6 and omega-3 balance, but that hasn't been studied for premenstrual symptoms specifically, so there's no evidence of an added benefit over taking either alone. What are the side effects of evening primrose oil? + Evening primrose oil's side effects are usually mild: nausea, headache, an upset stomach or loose stools [1]. Serious reactions are rare in the trials reviewed. If new symptoms appear after starting it, stop and mention them to a doctor at your next visit. Which is better for PMS mood symptoms, evening primrose oil or omega-3? + Neither has strong evidence for PMS mood symptoms in the trials reviewed here. Evening primrose oil's best-controlled studies found no benefit over placebo for mood [3] [5], and omega-3 wasn't tested for PMS mood in these sources, so neither can be called better. ## Sources - 1. [The effect of Oenothera biennis (Evening primrose) oil on inflammatory diseases: a systematic review of clinical trials](https://doi.org/10.1186/s12906-024-04378-5), BMC complementary medicine and therapies, 2024 - 2. [Is evening primrose oil of value in the treatment of premenstrual syndrome?](https://doi.org/10.1016/0197-2456(95)00082-8), Controlled clinical trials, 1996 - 3. [Evening primrose oil and treatment of premenstrual syndrome](https://doi.org/10.5694/j.1326-5377.1990.tb136857.x), The Medical journal of Australia, 1990 - 4. [Evening Primrose ( Oenothera biennis ) Oil in Management of Female Ailments](https://doi.org/10.6118/jmm.18190), Journal of menopausal medicine, 2019 - 5. [A double‐blind trial of evening primrose oil in the premenstrual syndrome: Nervous symptom subgroup](https://doi.org/10.1002/hup.470030110), Human Psychopharmacology Clinical and Experimental, 1988 - 6. [Vitamin E and evening primrose oil for management of cyclical mastalgia: a randomized pilot study](https://pubmed.ncbi.nlm.nih.gov/20359269/), Alternative medicine review : a journal of clinical therapeutic, 2010 - 7. [The Effect of Evening Primrose and vitamin B6 on premenstrual syndrome: a randomized clinical trial](https://doi.org/10.22038/ijogi.2019.12660), DOAJ (DOAJ: Directory of Open Access Journals), 2019 - 8. [Effect Of Evening Primrose On Premenstrual Syndrome: A Randomized Clinical Trial](https://doi.org/10.5281/zenodo.1157976), Zenodo (CERN European Organization for Nuclear Research), 2018 Ask AI about this page Copy prompt ChatGPT ↗ Claude ↗ Perplexity ↗ Google AI Mode ↗ Grok ↗ On this page - [How do evening primrose oil and omega-3 differ?](#how-do-evening-primrose-oil-and-omega-3-differ) - [Is evening primrose oil omega-3 or omega-6?](#is-evening-primrose-oil-omega-3-or-omega-6) - [Which works better for PMS or PMDD?](#which-works-better-for-pms-or-pmdd) - [How do the side effects compare?](#how-do-the-side-effects-compare) - [Can you switch from one to the other, or take both?](#can-you-switch-from-one-to-the-other-or-take-both) - [Which should you ask your doctor about?](#which-should-you-ask-your-doctor-about) - [Research](#research) - [Questions](#faq) Niyora PMS & PMDD support For the hard moment before your period. Private, no account. [Get it on iPhone](https://apps.apple.com/app/niyora-pms-emotions/id6764561688) ## Keep reading Treatment Evening primrose oil: what it is and whether it helps PMS Treatment Evening primrose oil for PMS: does it work? Treatment Evening primrose oil for PMDD: does it work? Treatment Evening primrose oil side effects, including mood Treatment Evening primrose oil 1000 mg: dosage, timing, and benefits Treatment How long until evening primrose oil works, and what are the signs? Treatment Evening primrose oil for mood swings: what the trials found Treatment Evening primrose oil for perimenopause mood: does it work? Treatment PMS treatment: what actually helps