Evening Primrose Oil Benefits and Risks

What Research Says About Its Uses for PMS, Bone Health and More

Primrose oil softgels

Verywell / Anastasia Tretiak

Evening primrose oil benefits range from claims that it works for inflammation and pain to helping with women’s health conditions like menopause symptoms. Even though it is commonly used as a natural medicine, research does not support taking evening primrose oil as a treatment for any medical condition.

Evening primrose oil is extracted from the seeds of Oenothera biennis, a plant native to North America and South America. It gets its name from its yellow blossoms, which bloom in the evening. The oil contains linoleic acid, gamma-linolenic acid (GLA), and other omega-6 fatty acids.

This article explores the research on evening primrose oil, what it's commonly taken for, and its potential side effects. You'll also learn about common dosages for evening primrose oil and how to store products safely.

Dietary supplements are not regulated the way drugs are in the United States, meaning the Food and Drug Administration (FDA) does not approve them for safety and effectiveness before products are marketed. When possible, choose a supplement that has been tested by a trusted third party, such as USP, ConsumerLab, or NSF. However, even if supplements are third-party tested, it doesn’t mean they are necessarily safe for all or effective in general. Therefore, it is important to talk to your healthcare provider about any supplements you plan to take and to check in about any potential interactions with other supplements or medications.

Supplement Facts

  • Active Ingredients: Linoleic acid, gamma-linolenic acid (GLA), omega-6 fatty acids
  • Alternate Names: Oenothera biennis
  • Legal Status: Over-the-counter (OTC) dietary supplement in the United States
  • Suggested Dose: 500 milligrams (mg) to 2,000 mg daily
  • Safety Considerations: To be avoided if taking blood thinners

Benefits of Evening Primrose Oil

Supplement use should be individualized and vetted by a healthcare professional, such as a registered dietitian, pharmacist, or healthcare provider. No supplement is intended to treat, cure, or prevent disease.

Evening primrose oil has mostly been studied for what it can do for women. For example, it’s been looked at for conditions related to menstruation and menopause like cyclical breast pain, premenstrual syndrome (PMS), hot flashes, and osteoporosis. Evening primrose oil has also been studied to treat skin and inflammatory conditions.

The way evening primrose oil works is not understood yet. Some research has suggested the chemical components in the oil extracted from the seeds are the key elements to its benefits. Specifically, GLA, an omega-6 fatty acid is thought to offer a range of benefits.

The evidence for evening primrose oil as a treatment is supported by small, preliminary studies and reviews of those studies. Some of these studies were done in GLA itself rather than evening primrose oil. The research is limited, and conclusions about its effects can’t be drawn yet.

Reduce Menstruation Pain

Some people claim that evening primrose oil helps with menstruation and other hormone-related problems and discomfort. Some studies have looked at how evening primrose oil might benefit menstruation pain. 

Cyclical Breast Pain

Evening primrose oil has been studied as a way to treat cyclical breast pain linked to the menstrual cycle (usually about a week before your period). However, the results of this research have been mixed.

Studies of evening primrose oil for breast pain treated participants for two, three, six, or 12 months and found that it may be effective and helpful for improving cyclic breast mastalgia (pain).

In another study, researchers looked at the findings from 13 clinical studies that used evening primrose oil to treat breast mastalgia. The oil was compared with vitamin E, topical nonsteroidal anti-inflammatory drugs (NSAIDs), and danazol (a hormone). The researchers concluded that evening primrose oil was not better or worse than the other treatments for breast pain.

Researchers also reviewed five studies that compared evening primrose oil with a placebo treatment, one study that compared the oil with bromocriptine and danazol, and one study that compared it with vitagnus. The placebo studies suggested that participants who took evening primrose oil had less pain than the people who were in the placebo group (no treatment). In the bromocriptine and danazol study, 55% of the participants who took evening primrose oil reported less breast pain. 

In the vitagnus study, the average pain reported by participants decreased in the evening primrose oil group; however, the decrease was not significantly different from the treatment group.

Premenstrual Syndrome (PMS)

Evening primrose oil has been studied to treat PMS, a common group of symptoms linked to the menstrual cycle. Symptoms of PMS vary in severity and can include cramps and mood changes.

One review of research highlighted eight studies that compared evening primrose oil with a placebo for PMS and one study comparing GLA (an omega-6 fatty acid) with a placebo. The evening primrose oil study showed a significant decrease in PMS severity, while the GLA study showed a shortened duration and decreased severity of PMS.

Perimenopause and Menopause

Evening primrose oil has been studied to treat hot flashes during perimenopause, the transitional period to menopause. This sudden feeling of extreme warmth in the upper body is a form of flushing caused by hormonal changes that may be related to reduced levels of the hormone estradiol.

Researchers did a study of 80 people who were postmenopausal comparing black cohosh and evening primrose oil as treatments for hot flashes. The severity of symptoms in both groups improved significantly after eight weeks, but black cohosh was more effective than evening primrose oil in reducing the number of hot flashes people had.

Researchers did another study on 170 people who used evening primrose oil with a placebo for hot flashes. Though there was no difference between groups in terms of helping with hot flashes, the study did show that the people in the treatment group reported fewer and less severe night sweats.

One six-week study compared evening primrose oil against a placebo for hot flashes in 56 people who were menopausal. The study showed improvements in the treatment group with decreased severity of hot flash symptoms, improvement in social activities, and improvement in sexuality. Similar to the other studies, there was no decrease in the frequency of hot flashes.

The use of evening primrose oil might be promising for conditions related to menstruation and menopause, but more high-quality research studies are needed. 

Improve Bone Health

Researchers are interested in the possible connection between unsaturated fat and a reduced risk of osteoporosis. Osteoporosis is a condition in which bone mineral loss causes the bones to get weak and brittle. The condition primarily affects people who have completed menopause.

Although omega-6 fatty acids are found in evening primrose oil, some studies have looked at the bone density effects of all polyunsaturated fatty acids, which include omega-3 and others.

In one study, researchers reviewed polyunsaturated fatty acids and bone mineral density. The review included an 18-month study of a combined treatment with evening primrose oil, fish oil, and calcium supplements. The results showed slowed or reversed bone loss in older people taking supplements compared to a control group who got a placebo.

In a large-scale genetics study, researchers looked at genetic information from several thousand people. They were looking for a connection between omega-6 fatty acids and bone mineral density. 

The study showed associations between fatty acids and bone mineral density but not omega-6 fatty acids. While this was a genetic study and not a clinical study of a treatment, it might be an avenue for future research.

Treat Skin Conditions

Some claims say that evening primrose oil has benefits for people with certain skin disorders.

Eczema

Eczema (atopic dermatitis) is a skin condition that causes scaly and inflamed skin. As part of a review of borage oil and evening primrose oil for eczema, researchers looked at 19 studies comparing evening primrose oil with a placebo. The studies found that evening primrose oil was not more effective for treating eczema than a placebo.

Acne

Acne, a condition in which pores get clogged with oil and dead skin cells, has also been treated with evening primrose oil.

One small, nine-month study had 50 participants add evening primrose oil to isotretinoin, a standard acne treatment. Twenty-five of the participants were given isotretinoin alone, and 25 were given evening primrose oil and isotretinoin. Improvement in acne was observed in both groups, and the group that took evening primrose oil also noticed additional skin hydration.

Psoriasis

Evening primrose oil and other sources of fatty acids are often studied for psoriasis, a condition that causes scaly and itchy patches of skin.

In one review, researchers looked at the effects of fatty acids, including evening primrose oil, on the processes in the body thought to be involved in psoriasis. The researchers found that evening primrose oil, linoleic acid, and other fatty acids were beneficial for psoriasis, but the review did not provide specific information about how it could be used as a treatment.

Skin Appearance

Many skincare products use evening primrose oil and claim it helps with the look and feel of skin. An older study found that evening primrose oil appeared to increase skin firmness, elasticity, and hydration. More research is needed to determine whether evening primrose oil really has these benefits for the look and feel of skin.

Relieve Rheumatoid Arthritis Pain

Rheumatoid arthritis (RA) is an autoimmune disease in which the immune system attacks and damages the joints. 

In one 12-week study, 60 participants with active rheumatoid arthritis were assigned to take fish oil, or fish oil and evening primrose oil. At the end of the study, both groups had improvements in disease activity score and the number of tender joints plus decreased pain.

Heart Health

Researchers have looked at whether evening primrose oil might have cardiovascular health benefits—but not in humans.

A 2014 study in rats modeled heart attacks in animals eating a high-fat diet. The rats that were given evening primrose oil to see if it would help with some risks for heart attacks, like blood clots and high cholesterol.

While the study suggested that evening primrose oil might have been beneficial for reducing these risks, studies in rats do not necessarily show what would happen in humans. High-quality research studies in humans would need to be done to find out whether evening primrose oil could have heart health benefits.

A review of studies that did include humans looked at whether evening primrose oil might help lower cholesterol. The review suggested that the supplement might help lower total cholesterol levels and raise HDL or “good” cholesterol levels. However, more research is needed to confirm the findings.

Since high cholesterol is a risk factor for cardiovascular disease, if evening primrose is proven to help lower it, that could be a potential heart health benefit. More high-quality research studies are needed.

Ease Multiple Sclerosis Symptoms

Multiple sclerosis is an autoimmune disease that affects the coverings of nerves in the brain and spinal cord. It can be relapsing (gets better, then worse) or progressive (continues to worsen).

In one study, researchers compared evening primrose oil and a placebo treatment in 52 people with multiple sclerosis. After three months, the researchers found that the treatment group reported improved pain, fatigue, and cognitive function compared to the placebo group.

However, conclusions cannot be drawn from this study alone because it was very small. 

Treat Diabetic Neuropathy

Evening primrose oil has been studied as a possible treatment for diabetic neuropathy, a condition of nerve dysfunction resulting from long-term diabetes.

In a 12-week study, 73 participants with diabetic neuropathy took GLA, alpha lipoic acid, or a placebo. Both treatment groups reported decreased pain and total symptoms compared to the placebo group. However, there was not a statistically significant difference between the two treatment groups.

Another 12-month study used vitamin E and evening primrose oil to treat 80 people with painful diabetic neuropathy. The researchers concluded that evening primrose oil combined with vitamin E improved pain in 88% of the participants.

These studies were small and used combination treatments rather than just evening primrose oil, so the results are not significant enough to prove that evening primrose oil on its own can treat diabetic neuropathy.

What Are the Side Effects of Evening Primrose Oil?

There has not been much research on the long-term safety of evening primrose oil. Shorter studies have noted some side effects. 

Common Side Effects

Evening primrose oil may cause side effects such as:

  • Stomach upset
  • Bloating
  • Headache
  • Nausea and altered taste
  • Diarrhea
  • Seizure

Most of the side effects are mild and get better on their own once the treatment is stopped.

Severe Side Effects

Information about the severe side effects of using evening primrose oil is lacking. It’s possible that some people have serious side effects from a supplement like evening primrose oil. 

If you are using evening primrose oil and have signs of a severe allergic reaction like hives, cramping, and diarrhea, call 911 or go to the ER.

Precautions

Evening primrose oil should be used with caution if you have certain medical conditions. Always talk to your provider before starting any supplement, even one available over-the-counter (OTC). 

  • Evening primrose oil may increase the risk of bleeding. If you have a bleeding disorder, be very careful if you use evening primrose oil. 
  • If you will be having surgery, your provider may want you to stop taking evening primrose oil. Any medicine or herb that affects how your blood clots or increases the risk of bleeding should be stopped for at least two weeks before surgery. Ask your healthcare provider if you are not sure if you need to stop taking any of your medications or supplements before surgery.
  • Although there is an ongoing study about evening primrose oil for the induction of labor in pregnancy, there is not yet enough evidence to make a recommendation. Always talk to your provider about taking any kind of supplement while you’re pregnant.
  • It’s not clear if evening primrose oil is safe while you’re breastfeeding. Talk to your provider about any supplements you're considering if you plan to breastfeed.

It’s important to always tell your healthcare provider about all the supplements you take. They can help make sure they won’t interact with any medications or conditions you have. 

Dosage: How Much Evening Primrose Oil Should I Take?

Always speak with a healthcare provider before taking a supplement to ensure that the supplement and dosage are appropriate for your individual needs.

The Food and Drug Administration (FDA) does not regulate supplements in the same way they regulate drugs. That means there are no universal guidelines regarding the appropriate use of evening primrose oil.

Evening primrose oil is generally considered safe for use in adults. There is no recommended dosage of evening primrose oil. Doses used in research studies ranged from 240 milligrams daily to 4 grams daily. If you take evening primrose oil every day, you might be more likely to have side effects.

Since there isn’t enough research to prove its safety, evening primrose should not be given to children or older adults without first asking a healthcare provider.

Evening primrose oil is available in many health food stores and pharmacies. It is usually sold in gelcap form. Bottled primrose oil is also available, but it is harder to get an exact dose if you take it this way. 

Interactions

Evening primrose oil can interact with several medications, either reducing the drug's efficacy or causing side effects, including:

  • Anticoagulants (blood thinners) like Jantoven (warfarin)
  • NSAIDs like diclofenac, ibuprofen, and aspirin
  • Antipsychotic drugs like chlorpromazine (a phenothiazine drug)
  • Human immunodeficiency virus (HIV) medications, such as lopinavir

It is essential to carefully read a supplement's ingredient list and nutrition facts panel to know which ingredients and how much of each ingredient is included. Please review the supplement label with your healthcare provider to discuss potential interactions with foods, other supplements, and medications.

Primrose oil soft gels
Verywell / Anastasia Tretiak 

How to Store Evening Primrose Oil

Evening primrose oil has a high amount of unsaturated fats, which go through a breakdown process called oxidative deterioration. This breakdown means the quality of the supplements is compromised. Any product that’s rich in unsaturated oil can go rancid, including bottled primrose oil and primrose oil gel caps.

Storage instructions vary for different products. Carefully read the directions and packaging label on the container. Keep medications tightly closed and out of the reach of children and pets, ideally locked in a cabinet or closet. Try to store your medications in a cool and dry place.

Discard after one year or as indicated on the packaging. Avoid pouring unused and expired products down the drain or in the toilet. Visit the FDA's website to know where and how to discard all unused and expired medications. You can also find disposal boxes in your area. Or, ask your healthcare provider about the best ways to dispose of your medications or supplements.

If you plan to travel with evening primrose oil, know the regulations of your final destination. The U.S. Embassy or Consulate might be a helpful resource.

Similar Supplements

Similar supplements include but aren't limited to:

Like evening primrose, borage oil contains significant amounts of GLA.

Sources of Evening Primrose Oil and What to Look For

Evening primrose oil is not present in foods. It can only be found in the seeds of the Oenothera biennis plant. If you want to use it, you’ll have to take a supplement. 

However, some of the specific fatty acids in evening primrose oil, like linoleic acid and GLA, are present in foods like:

  • Seeds
  • Oils
  • Nuts

Other fatty acids with health benefits are also found in meats and fish.

Evening primrose oil supplements are available in pharmacies, health food stores, and online.

To ensure quality and safety, only buy supplements certified by an independent body, such as the USP (U.S. Pharmacopeia), NSF, or ConsumerLab.

Evening Primrose Oil Supplements

Evening primrose oil comes as a capsule, gelcap, or oil.

If you are strictly vegan or vegetarian, only choose brands labeled "vegetarian-safe" or "vegetarian soft gels." Unless this is stated clearly on the label, the capsule may be made with animal-based gelatin derived from cows or pigs.

Summary

Evening primrose oil comes from the seed of the evening primrose plant. It contains linoleic acid and GLA, which are omega-6 fatty acids.

Some studies have supported using evening primrose oil for some conditions that cause pain or inflammation. However, since the research is limited and has shown mixed, the claims about health benefits are not conclusive and well-supported. 

Evening primrose oil can be purchased as a dietary supplement at most pharmacies and health food stores. Talk about it with your healthcare provider first before trying evening primrose oil. Mention any medications you are taking and conditions you have (especially bleeding disorders) to make sure it’s safe for you. 

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Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Carla Eisenstein, PharmD
Carla Eisenstein is a pharmacist and medical writer passionate about clear communication in science and medicine. She has experience in drug information, medical communication, social media, and patient advocacy.

Originally written by Cathy Wong