Evening primrose oil (EPO) is made from the seeds of evening primrose flowers, native to North America. People traditionally used it to treat conditions including 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.

EPO may have some potential benefits. However, more research is still needed to confirm its use.

The National Center for Complementary and Integrative Health (NCCIH) states there isn’t enough evidence to support using EPO for any health conditions.

Despite that, it’s generally safe to use long-term, and some studies have highlighted areas of possible benefit. These may include:

1. It may help ease acne

Some people believe the GLA in EPO may 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 2022 study, EPO may help relieve specific side effects from the medication isotretinoin (Accutane).

An older 2014 study found that GLA supplementation reduced inflammatory and noninflammatory acne lesions.

However, larger, longer studies are still needed to determine the safety and effectiveness of evening primrose oil.

2. It may help ease eczema

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

A 2018 study in South Korea concluded that EPO improved the Eczema Area Severity Index (EASI) score in people with mild eczema compared to a placebo. The studies’ authors noted that transepidermal water loss and skin hydration were slightly improved in the EPO group.

The review didn’t look at the effectiveness of topical EPO for eczema.

3. It can help improve overall skin health

The GLA in EPO may benefit skin structure and function. Because the skin can’t produce GLA alone, taking GLA-rich EPO may help keep the skin healthy.

Both previously mentioned studies noted that EPO improved skin hydration in participants.

According to an older 2005 study, oral supplementation of EPO may help smooth skin and improve its:

  • elasticity
  • moisture
  • firmness
  • fatigue resistance

4. It may help relieve PMS symptoms

A 2019 study suggests EPO may be effective in treating premenstrual syndrome (PMS) symptoms, such as:

  • breast swelling
  • irritability
  • bloating
  • acne

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

5. It may help minimize breast pain

Some people may use EPO to relieve cyclical breast pain. Some people believe the GLA in EPO is thought to reduce inflammation and help inhibit prostaglandins that cause cyclical breast pain.

However, a 2021 review of research found that EPO was only as effective as a placebo compared to topical nonsteroidal anti-inflammatory drugs (NSAIDs), danazol, or vitamin E.

The authors also noted that EPO is unlikely to cause adverse side effects. So it may be safe to try.

6. It may help reduce hot flashes

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

A small 2021 study that used participant questionnaires found that taking EPO during menopause may result in less frequent and less severe night sweats.

However, the National Center for Complementary and Integrative Health (NCCIH) notes that there’s not enough evidence to support the effectiveness of EPO for hot flashes or other menopause side effects.

7. It may help improve heart health

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 using natural remedies, such as EPO, to help.

A 2020 review of research suggests that EPO may have a beneficial effect on cholesterol levels, though some research was inconclusive. Additional research is still needed to support the use of EPO to support heart health.

9. It can help reduce nerve pain

Peripheral neuropathy is a common side effect of diabetes and other conditions. A 2018 review of research notes that animal studies have shown that fatty acids like linolenic acid may potentially help reduce neuropathy symptoms, such as:

  • hot and cold sensitivity
  • numbness
  • tingling
  • weakness

However, human clinical trials are still needed to show whether these results may extend to humans.

10. It may help ease bone pain

Bone pain is often caused by rheumatoid arthritis, a chronic inflammatory disorder. According to a small 2017 study, the GLA in EPO can potentially reduce rheumatoid arthritis pain without causing unwanted side effects.

However, larger studies are still needed to confirm this.

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

Supplements aren’t monitored for quality by the Food and Drug Administration (FDA). When choosing EPO, research the supplement and the company selling the product. Choosing one that has been certified by a third party may be safer.

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.

There’s not enough research on EPO to determine its safety during pregnancy or breastfeeding.

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 experience any of the above symptoms after taking EPO, call 911 or your local emergency services.

EPO may interact with some medications.

If you take blood thinners, EPO may increase bleeding.

EPO may potentially lower blood pressure, so do not take it if you take medications that lower blood pressure or blood thinners.

EPO may also increase the effect of the HIV medication lopinavir.

Does evening primrose oil help you sleep?

While there’s not enough research to prove that EPO helps with sleep, some people report it helps them. EPO may reduce inflammation and pain, which may help some people sleep better.

What does evening primrose oil do to female hormones?

Researchers believe EPO may help lower prolactin levels, reducing symptoms of PMS. Some people report that EPO also helps reduce cyclical breast pain and hot flashes.

Who shouldn’t take evening primrose oil?

EPO may interact with some medications, so people who take blood thinners, some blood pressure medications, or the HIV treatment lopinavir should not take EPO.

Slight evidence suggests that EPO may benefit some conditions 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 a doctor.

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

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