Evening primrose oil is a rich source of anti-inflammatory gamma linoleic acid (GLA). Although proponents claim that this oil may help with conditions such as eczema, dry eye, chronic pain, and women’s hormonal issues, there is insufficient evidence to support most uses. Read on to learn more about the potential health benefits and side effects of evening primrose oil.
What Is Evening Primrose Oil?
Evening primrose (Oenothera biennis) is a flowering plant belonging to the willowherb family (Onagraceae). It is native to North America but also grows wild in Europe and parts of the Southern hemisphere.
The seeds of this plant are rich in gamma linolenic acid (GLA), an omega-6 fatty acid with many potential health benefits [1, 2].
Unlike evening primrose, many plants and vegetable oils contain linoleic acid, which has to be converted to GLA in the body to achieve the desirable effects. Evening primrose oil contains GLA, so it bypasses this activation step [3].
Essential fatty acids are necessary for maintaining good health, but cannot be made by the body – they have to be taken in through food. Their actions are diverse and include boosting skin health and hair growth, maintaining bone health, regulating metabolism, and maintaining fertility [4].
Gamma-linolenic acid in evening primrose oil may support brain function and decrease inflammation. It’s become a popular supplement for immune system disorders, including autoimmune diseases and conditions characterized by chronic inflammation [5, 6, 1, 7].
It can be taken as a supplement or applied to the skin. The primary uses of the oil are for eczema, skin health, menstrual and menopausal symptoms, and lactation. It’s also used for diabetic neuropathy, premenstrual syndrome, rheumatoid arthritis, essential fatty acid deficiencies, dandruff, and some pregnancy-related complications [4].
Components
The seed contains 15% proteins, 24% oil, and 43% fiber.
The fatty acid components in the seed include about 70% linoleic and 10% gamma-linolenic (GLA) acid, while the rest make oleic, palmitic, and stearic acids [4].
Once the oil is pressed from the seeds, the fibers are removed and the percentage of fatty acids rises.
The oil contains long-chain fatty alcohols, which also reduce inflammation, and two phytosterols: campesterol and beta-sitosterol [8, 4].
How Does Evening Primrose Oil Work?
Evening primrose oil fights oxidative stress in tissues and increases the master antioxidant glutathione, mainly in heart and blood. Boosting glutathione protects the tissues in the body from stressors [3].
GLA and alcohols in evening primrose oil also block inflammatory pathways in the body, reducing inflammatory substances, enzymes, and cascades [8, 9].
Snapshot
Proponents
- May improve rheumatoid arthritis
- May help with skin disorders
- May help prevent heart disease
- May help with nerve damage
- May help with blood sugar control
- May improve dry eye
Skeptics
- Insufficient evidence for most benefits
- Not recommended in people with bleeding disorders or scheduled surgery
- Not safe for pregnant women
- May cause allergies
- May interfere with blood thinners and lithium
Health Benefits
Rheumatoid Arthritis
No significant improvements in joint pain, stiffness, and swelling were observed in two 12-week clinical trials from the 1980s using evening primrose oil in 38 people [10, 11].
However, another trial on 40 people found that evening primrose oil (6 g/day) mildly improved morning stiffness and joint pain [12].
More recently, evening primrose oil, fish oil (rich in EPA), and their combination reduced rheumatoid arthritis symptoms, painkiller use, and the risk of heart disease in 2 trials on 109 people [13, 14].
Although no meta-analyses specific to evening primrose oil have been conducted, one on GLA concluded that it may reduce pain and disability in people suffering from rheumatoid arthritis [15].
Although the evidence is limited and includes trials with mixed results, it overall suggests that evening primrose oil may help with rheumatoid arthritis symptoms. You may discuss with your doctor if it may help as an add-on to your treatment regime.
Insufficient Evidence
1) Skin Conditions
Eczema
Eczema is a very common chronic inflammatory skin condition that may require a combination of treatment approaches. Some researchers believe that a defect in the function of the enzyme delta-6-desaturase, which is responsible for the conversion of linoleic acid to GLA, may be a factor in the development of this condition [16, 17].
Indeed, a study on 50 young adults with eczema found they had higher levels of cis-linoleic acid and GLA deficit. Supplementation with evening primrose oil corrected both this deficiency and eczema symptoms in this trial and 3 more on 56 adults and 24 children [18, 19, 20, 21].
In line with this, a trial on 21 people correlated the increase in GLA with the effectiveness of the evening primrose oil treatment [22].
Oral evening primrose oil improved eczema symptoms such as inflammation, dryness, scaling, itching, redness, and overall sensitivity after 4-8 weeks in 6 clinical trials on 149 adults and 130 children and adolescents [23, 24, 25, 26+, 27, 28].
However, oral evening primrose oil (2-4 g in children and 6-8 g in adults) wasn’t more effective than placebo in 3 clinical trials on 285 people with eczema. Similarly, it was ineffective in another trial on 39 people with hand dermatitis [29, 30, 31, 32].
In another trial on 24 people, topical evening primrose oil failed to prevent eczema caused by an ointment with the steroid betamethasone valerate [33].
The first meta-analysis conducted (in 1989) found evening primrose oil more effective than placebo at improving eczema symptoms, especially itching. However, one researcher pointed out that this meta-analysis was biased and included several non-peer reviewed studies while excluding a large trial with negative results [34, 35].
An update of the previous meta-analysis that included 26 studies and over 1,200 people concluded that evening primrose oil had benefits on eczema symptoms but lost effectiveness with the use of potent steroids [36]
The most recent meta-analysis on 27 studies and over 1,500 people (conducted by Cochrane) concluded that neither evening primrose nor borage oil were effective against eczema symptoms [37].
Because the results are mixed, we cannot conclude for certain that evening primrose oil (or any other sources of GLA) helps with eczema. More robust research is needed.
Skin Appearance
Evening primrose oil improved the overall appearance of the skin in a 12-week trial on 22 healthy adults. The oil increased skin moisture, elasticity, and firmness, while decreasing roughness [38].
A single, small clinical trial is insufficient to attest to the benefits of evening primrose oil for skin appearance. More clinical research is needed to confirm this preliminary finding.
Acne
In a 10-week study on 45 people with mild to moderate acne, a GLA supplement (borage oil) improved both inflammatory and non-inflammatory acne lesions [39].
GLA from hemp seed oil inhibited a microbe that causes acne (Propionibacterium acnes) in test tubes [40].
A small clinical trial and an antimicrobial study (both of which used GLA obtained from other sources than evening primrose oil) are clearly insufficient to support this potential benefit. More clinical trials using evening primrose oil are needed.
Skin Problems from Hemodialysis
People undergoing hemodialysis often have abnormal levels of blood fats and urea, which may cause skin problems with dryness, itching, and redness. In a small trial on 16 hemodialysis patients, oral evening primrose for 6 weeks improved these 3 symptoms. Larger, more robust clinical trials are needed to validate this preliminary result [41].
2) Preventing Heart Disease
Blood Fat Levels
High blood fats ( triglycerides and cholesterol) are one of the main risk factors for heart disease due to their potential to cause artery clogging. Platelets also play a role in artery clogging, since they bind to the blood vessel lining and recruit inflammatory cells.
In a trial from the 80s on insulin-dependent diabetics, evening primrose oil increased “good” HDL cholesterol levels and reduced the ability of the platelets to attach to the blood vessels [42].
Evening primrose oil supplementation lowered the blood levels of cholesterol (total and “bad” LDL cholesterol) and reduced platelet clumping in 2 clinical trials on 31 people with high blood fat levels, but was ineffective in 2 trials on 47 people with this condition [43, 44, 45, 46].
More recently, evening primrose oil combined with vitamin D co-supplementation for 12 weeks improved blood triglycerides, and “bad” VLDL and LDL cholesterol in 2 clinical trials on 60 women with polycystic ovarian syndrome and 60 pregnant women with diabetes [47, 48].
Evening primrose oil also reduced diet-induced artery clogging in mice [49].
Blood Clots
Thromboxanes constrict blood vessels, increase blood pressure, and increases clotting (platelet aggregation), while PGE1 helps relax blood vessels and increase blood flow. In a small trial on 7 non-insulin-dependent diabetics, a combination of evening primrose and fish oil lowered the ratio of thromboxanes to PGE1 [50].
Evening primrose oil has reduced platelet count and prevented them from clumping together in rabbits, rats, and mice [51, 52, 53, 54, 55].
To sum up, the effects of evening primrose oil on artery clogging have been tested in a few small trials with mixed results, in which those showing effectiveness often combined it with vitamin D. In turn, its effects on blood clot formation have been mainly tested in animals. The evidence is insufficient to back its role in protecting from heart disease until more clinical research sheds some light on this potential benefit.
3) Nerve Damage
In 2 clinical trials on over 100 diabetic people with nerve damage, taking 360 mg of GLA from evening primrose oil improved nerve function, especially in those with controlled blood sugar [56, 57].
Evening primrose oil improved blood flow to the nerves and promoted their development while reducing their breakdown, resulting in an improved nerve function, in rats with nerve damage due to diabetes, high blood galactose, and crush injuries [58, 59, 60, 61, 62, 63].
Although the results are promising, the evidence is insufficient to support the use of evening primrose oil in people with nerve damage. Larger, more robust clinical trials are needed to confirm these preliminary findings.
4) Diabetes
Evening primrose oil in combination with fish oil lowered fasting blood sugar in a small trial on 7 non-insulin-dependent diabetics. Its combination with vitamin D lowered fasting blood sugar and insulin while increasing insulin sensitivity in another trial on 60 women with diabetes caused by pregnancy [48, 50].
Two small clinical trials cannot be considered sufficient evidence that evening primrose oil helps with blood sugar control in diabetics until more clinical research is carried out.
5) Dry Eye
In a clinical trial on 76 women, oral evening primrose oil improved eye dryness from contact lens use [64].
Oral GLA from borage oil or unspecified sources (combined with other fatty acids and artificial tears) improved eye dryness and inflammation in 3 trials on over 150 people with pink eye [65, 66, 67].
However, evening primrose oil was ineffective at treating dry eye caused by Sjogren’s syndrome (an autoimmune disease that mainly attacks the glands that produce tears and saliva) in a small trial on 28 people [68].
Because the results are mixed and most studies didn’t clearly specify that they used GLA from evening primrose or combined it with other fatty acids and artificial tears, there is insufficient evidence to support the use of evening primrose oil in people with dry eye. More clinical trials using evening primrose oil alone are needed to validate these preliminary results.
6) Raynaud’s Syndrome
Raynaud’s syndrome is a rare condition with episodes of reduced blood flow, especially to the fingers and toes. In a clinical trial on 21 people with this condition, evening primrose oil supplementation reduced the frequency and severity of the attacks, as well as platelet clumping [69].
A single, small clinical trial cannot be considered sufficient evidence that evening primrose oil improves Raynaud’s syndrome. Further clinical studies are needed.
7) Kidney Stones
Evening primrose oil (1 g/day for 20 days) decreased kidney stone risk factors (blood levels of calcium and oxalate) in a small trial of 16 people [70].
Again, this small clinical trial is clearly insufficient to support this potential use of evening primrose oil. More clinical research is required to validate this result.
8) Hot Flashes
Oral GLA from evening primrose oil wasn’t more effective than the placebo at reducing the frequency of hot flashes in a clinical trial on 35 menopausal women. However, it did reduce their severity in another trial on 56 women [71, 72].
Further clinical research is warranted to shed some light on the potential effectiveness of evening primrose oil in women with hot flashes.
9) Multiple Sclerosis
An intervention with a special (“Hot-natured”) diet and evening primrose and hemp seed oil supplementation improved the fatty acid composition of red blood cells, overall symptoms and relapse rate, and the activity of liver and cell surface enzymes in a clinical trial on 100 people with multiple sclerosis [73, 74, 75, 76].
However, evening primrose oil had no effect on platelet activity in a small trial on 14 people. In another trial on over 100 people, purified GLA (from an unspecified source) had no effect on the duration and severity of multiple sclerosis attacks [77, 78].
Limited evidence suggests that evening primrose oil may have some positive effects when used in combination with another GLA source (hemp seed oil) and a special diet but not when used alone. However, we cannot conclude this for certain due to the small number of trials.
Possibly Ineffective
1) PMS
Five old clinical trials found evening primrose effective at improving PMS symptoms such as irritability, depression, breast tenderness, and fluid retention. However, a clinical trial on 38 women found it as effective as the placebo and a systematic review of 7 trials concluded that it was of little or no value in the management of PMS [79, 80, 81].
Evening primrose oil has been most widely studied regarding breast pain and tenderness. However, the results are mixed: while 3 clinical trials on over 250 women found it effective at reducing pain severity (especially if combined with vitamin E), 2 trials on almost 600 women found it as effective as the placebo [82, 83, 84, 85, 86].
Selective estrogen receptor modulators (centchroman) and topical non-steroidal anti-inflammatory drugs were clearly superior to evening primrose oil in 2 clinical trials on 160 women [87+, 88].
2) Asthma
Evening primrose oil (both alone and in combination with fish oil) was ineffective at improving asthma symptoms in 3 clinical trials on over 100 people [89, 90, 91].
3) ADHD
An evening primrose oil supplement (Efamol) produced little or no effects on ADHD symptoms in 3 clinical trials on 67 children with this condition [92, 93, 94].
4) High Blood Pressure during Pregnancy (Pre-Eclampsia)
Evening primrose oil (both alone and combined with fish oil) had no preventive effect on pre-eclampsia in 2 clinical trials on almost 200 pregnant women [95, 96].
5) Other Conditions
Evening primrose oil has only been evaluated in one clinical trial that produced negative results for the following conditions:
- Inducing labor (trial on 80 women) [97]
- Psoriasis (trial on 37 people) [98]
- IBD (trial on 43 people) [99]
- Obesity (trial on 100 women) [100]
- Stomach ulcers (trial on 20 people) [101]
- Hepatitis B (trial on 10 people) [102]
- Psoriatic arthritis (trial on 38 people) [103]
- Bone loss (trial on 43 pre- and postmenopausal women) [104]
- Chronic fatigue syndrome (trial on 50 people) [105]
- Liver cancer (trial on 62 people) [106]
Side Effects & Precautions
This list does not cover all possible side effects. Contact your doctor or pharmacist if you notice any other side effects.
Call your doctor for medical advice about side effects. In the US, you may report side effects to the FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch. In Canada, you may report side effects to Health Canada at 1-866-234-2345.
Evening primrose oil is generally safe when consumed at the recommended dosages. Some reported side effects include nausea, stomach pain, and headaches [107, 37].
According to the Natural Standard Research Collaboration, allergy or hypersensitivity to oral evening primrose oil is uncommon but it may cause contact dermatitis [4].
A case report warned that its prolonged intake (for over one year) may cause inflammation, thrombosis, and immunosuppression [37].
Lipoid pneumonia is an underdiagnosed disease caused by the aspiration of lipid particles into the lungs. A 50-year-old woman developed this condition from using evening primrose oil in the long term. The condition improved when she stopped taking it [108].
Due to its potential blood-thinning effects, evening primrose oil should not be consumed by people with bleeding disorders or with a scheduled surgery.
Due to the lack of safety data, pregnant or breastfeeding women are advised to avoid evening primrose oil.
Drugs Interactions
Supplement/Herb/Nutrient-drug interactions can be dangerous and, in rare cases, even life-threatening. Always consult your doctor before supplementing and let them know about all drugs and supplements you are using or considering.
Evening primrose oil may act as a blood thinner and add to the anticoagulant effects of medication such as warfarin [37].
For this same reason, it’s also important to be cautious and consult a doctor before combining evening primrose oil with other herbs that may increase bleeding time such as angelica, clove, danshen, garlic, ginger, ginkgo, red clover, and turmeric.
Evening primrose oil also has the potential to reduce serum lithium levels, so people on this medication (e.g., those with bipolar disorder) should consult their doctor before taking this oil [109].
Natural Sources and Forms of Supplementation
Evening primrose oil supplements have not been approved by the FDA for medical use due to the lack of solid clinical research. Regulations set manufacturing standards for supplements but don’t guarantee that they’re safe or effective. Speak with your doctor before supplementing with evening primrose oil.
Oral evening primrose oil is typically sold in capsules, tablets, and liquid solutions.
The oil can also be applied topically on the face, wounds, or skin regions with eczema and acne.
Dosage
Because evening primrose oil is not approved by the FDA for any condition, there is no official dose. Users and supplement manufacturers have established unofficial doses based on trial and error. Discuss with your doctor if evening primrose may be useful as a complementary approach in your case and which dose you should take.
The recommended daily dose of evening primrose oil is 4-5 capsules, tablets, or drops before or after each meal. Capsules and tablets typically contain 500 mg evening primrose oil [31].
User Experiences
The opinions expressed in this section are solely those of evening primrose oil users, who may or may not have medical or scientific training. Their reviews do not represent the opinions of SelfHacked. SelfHacked does not endorse any specific product, service, or treatment.
Do not consider user experiences as medical advice. Never delay or disregard seeking professional medical advice from your doctor or other qualified healthcare providers because of something you have read on SelfHacked. We understand that reading individual, real-life experiences can be a helpful resource, but it is never a substitute for professional medical advice, diagnosis, or treatment from a qualified healthcare provider.
Users mainly used evening primrose oil for conditions such as chronic pain, skin health, hot flashes, and premenstrual symptoms. Several of the users were satisfied and reported dramatic improvements.
However, some users complained that the supplement didn’t work in their case. The adverse effects most commonly reported were mood swings and nausea.
