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Evening primrose oil (EPO) is made from the seeds of the flowers of a plant native to North America. It has traditionally been used to treat conditions such as bruises, hemorrhoids, and sore throats.

EPO’s healing benefits may be due to its gamma-linolenic acid (GLA) content. GLA is an omega-6 fatty acid found in plant oils.

EPO is generally taken as a supplement or applied topically. Read on to learn how EPO may help treat many common health conditions today.

Ready to give it a try? Find EPO here.

The GLA in EPO is thought to help acne by reducing skin inflammation and the number of skin cells that cause lesions. It may also help the skin retain moisture.

According to a 2014 study, EPO may help relieve cheilitis. This condition causes inflammation and pain in the lips caused by the acne drug isotretinoin (Accutane).

A separate study found that GLA supplementation reduced both inflammatory and noninflammatory acne lesions.

How to use: Participants in the cheilitis study received six 450-milligram (mg) capsules of EPO three times daily for a total of eight weeks.

Some countries other than the United States have approved EPO to treat eczema, an inflammatory skin condition.

According to an older study, the GLA in EPO may improve the skin’s epidermis. However, a 2013 systematic review concluded that oral EPO doesn’t improve eczema and isn’t an effective treatment. The review didn’t look at the effectiveness of topical EPO for eczema.

How to use: In studies, one to four EPO capsules were taken twice daily for 12 weeks. To use topically, you can apply 1 milliliter (mL) of 20 percent EPO to the skin twice daily for up to four months.

According to a 2005 study, oral supplementation of EPO helps smooth skin and improve its:

  • elasticity
  • moisture
  • firmness
  • fatigue resistance

Per the study, GLA is necessary for ideal skin structure and function. Because the skin can’t produce GLA on its own, researchers believe taking GLA-rich EPO helps keep skin healthy overall.

How to use: Take 500-mg EPO capsules three times daily for up to 12 weeks.

An older study suggests EPO is highly effective in treating premenstrual syndrome (PMS) symptoms, such as:

Researchers believe some women experience PMS because they’re sensitive to normal prolactin levels in the body. GLA converts to a substance in the body (prostaglandin E1) thought to help prevent prolactin from triggering PMS.

According to a 2010 study, a supplement containing vitamin B-6, vitamin E, and EPO was effective in relieving PMS. Even so, it’s unclear how much EPO played a role, since a 2009 systematic review didn’t find EPO helpful for PMS.

How to use: For PMS, take 6 to 12 capsules (500 mg to 6,000 mg) one to four times daily for up to 10 months. Start with the smallest dose possible, and increase as needed to relieve symptoms.

If you experience breast pain so severe during your period that it interferes with your life, taking EPO may help.

According to a 2010 study, the GLA in EPO is thought to reduce inflammation and help inhibit prostaglandins that cause cyclical breast pain. The study found that taking daily doses of EPO or EPO and vitamin E for six months decreased the severity of cyclical breast pain.

How to use: Take 1 to 3 grams (g) or 2.4 mL of EPO daily for six months. You can also take 1,200 mg of vitamin E for 6 months.

EPO may reduce the severity of hot flashes, one of the most uncomfortable side effects of menopause.

According to a 2010 literature review, there’s not enough evidence that over-the-counter remedies such as EPO help hot flashes.

A later study, however, came to a different conclusion. The study found that women who took 500 mg daily of EPO for six weeks experienced less frequent, less severe, and shorter hot flashes.

Women also had improved marks for social activity, relations with others, and sexuality on a questionnaire on how hot flashes impact daily life.

How to use: Take 500 mg of EPO twice daily for six weeks.

There’s conflicting evidence about whether EPO lowers blood pressure. More research is needed.

According to a 2013 study, those taking EPO had a slightly higher systolic blood pressure. Researchers called the reduction “a clinically meaningful difference.”

A 2011 systemic review concluded there’s not enough evidence to determine if EPO helps reduce the risk of high blood pressure during pregnancy or preeclampsia, a condition that causes dangerously high blood pressure during and after pregnancy.

How to use: Take a standard dose of 500 mg of EPO twice daily under your doctor’s supervision. Don’t take with other supplements or medications that may lower your blood pressure.

Heart disease kills more than 600,000 people in the United States each year. Hundreds of thousands more are living with the condition. Some people are turning to natural remedies, such as EPO, to help.

According to a 2014 study on rats, EPO is anti-inflammatory and helps reduce blood cholesterol. Most people with heart disease have inflammation in the body, although it hasn’t been proven that inflammation causes heart disease.

How to use: Under a doctor’s supervision, take 10 to 30 mL of EPO for four months for overall heart health. Use with caution if you take other medications that affect the heart.

Peripheral neuropathy is a common side effect of diabetes and other conditions. Older research has shown that taking linolenic acid helps reduce neuropathy symptoms, such as:

  • hot and cold sensitivity
  • numbness
  • tingling
  • weakness

How to use: Take EPO capsules containing 360 to 480 mg GLA daily for up to one year.

Bone pain is often caused by rheumatoid arthritis, a chronic inflammatory disorder. According to a 2011 systematic review, the GLA in EPO has the potential to reduce rheumatoid arthritis pain without causing unwanted side effects.

How to use: Take 560 to 6,000 mg of EPO daily for 3 to 12 months.

EPO is generally considered safe for most people to use short term. The safety of long-term use hasn’t been determined.

Keep in mind supplements aren’t monitored for quality by the Food and Drug Administration. When choosing EPO, research the supplement as well as the company selling the product.

Side effects of EPO are usually mild and may include:

  • upset stomach
  • stomach pain
  • headache
  • soft stools

Taking the least amount possible may help prevent side effects.

In rare cases, EPO may cause an allergic reaction. Some symptoms of allergic reaction are:

  • inflammation of the hands and feet
  • rash
  • difficulty breathing
  • wheezing

If you take blood thinners, EPO may increase bleeding. EPO may lower blood pressure, so don’t take it if you take medications that lower blood pressure or blood thinners.

Topical EPO is often used to help prepare the cervix for delivery. But according to the Mayo Clinic, a study reported taking EPO orally slowed dilation and was associated with longer labor. There’s not enough research on EPO to determine its safety for use during pregnancy or breastfeeding and can’t be recommended.

There’s evidence that EPO may benefit some conditions on its own or as a complementary therapy, but more research is needed. Until the verdict is clear, EPO shouldn’t be used in place of a treatment plan recommended by your doctor.

There’s no standardized dosing for EPO. Most dosage recommendations are based on what’s been used in research. Talk to your doctor to weigh the risks and benefits of taking EPO and get advice about the proper dosage for you.

To reduce your risks for side effects, always use the lowest dose possible. If you begin having unusual or persistent side effects, discontinue use and see your doctor.