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What is evening primrose?

The evening primrose is also known as the night willow herb. It’s a flowering plant with a yellow blossom that mostly grows in North America and Europe. While most flowering plants open with the sunrise, evening primrose opens its petals in the evening.

The oil that’s extracted from the seeds of this plant is commonly used as a health supplement, topical treatment, and ingredient in beauty products.

Evening primrose oil (EPO) is known for its hormone-balancing, anti-inflammatory, and antioxidant properties.

It’s also hailed as a tool for minimizing hair loss, but more research is needed to confirm this.

Keep reading to find out what we already know and what we’re still learning about evening primrose oil as a supplement for thick, healthy hair.

Evening primrose oil is rich in omega chain fatty acids.

Fatty acids are said to:

  • fight oxidative stress
  • reduce inflammation
  • encourage healthy cell growth

Because of this, it’s thought that EPO can help with hair loss caused by:

  • nutritional deficiency
  • environmental damage (such as sun exposure)
  • scalp inflammation

EPO also contains phytoestrogens, leading some to suggest it may improve the symptoms of hormone-related conditions like menopause. Hair loss is a common symptom of menopause, so EPO may pull double-duty here.

Research on using EPO for hair growth and overall hair health is limited. But there has been research on how certain ingredients or chemical components in EPO affect hair health.

Although this does give some insight into how EPO may affect hair loss, more research is needed to explicitly support or clarify EPO’s effect on hair health.

It may promote new growth

Like other plant oils, EPO contains arachidonic acid. This ingredient has been shown to promote new hair growth and help existing hair shafts to grow longer.

It may help reduce scalp inflammation and hair follicle damage

Gamma linoleic acid (GLA) is an omega chain fatty acid found in EPO. This ingredient is known for its anti-inflammatory properties.

Although there haven’t been studies on GLA and scalp inflammation, it has been studied as a therapy for inflammatory conditions like atopic dermatitis (eczema).

Some research also suggests that the sterols found in EPO can help reduce inflammation.

It may help reduce oxidative stress

The stress you put on your hair — think products, heat styling, and the like — can make alopecia-related hair loss worse.

EPO is rich in the antioxidant vitamin E, which is known to relieve oxidative stress.

Researchers in one 2010 study found that taking oral vitamin E supplements helped improve alopecia symptoms. Participants taking vitamin E supplements also had a higher hair count per inch of scalp than the participants who took the placebo.

This suggests that EPO could stimulate and protect hair follicles, keeping them healthy and active.

You can apply EPO topically, consume it orally, or both.

But don’t confuse “essential oil of evening primrose” with EPO (“evening primrose oil”). Essential oils are much stronger and give off the kind of volatile aromas used in aromatherapy.

If your hair loss is connected to inflammation, anecdotal evidence favors topical application.

If your hair loss is tied to a hormonal condition, supplements may be more beneficial than topical EPO.


Unlike drugs, herbal supplements aren’t regulated by the U. S. Food and Drug Administration (FDA). That means it’s critical that you only buy from manufacturers you trust.

You should also talk with your doctor about your individual risk of side effects or interactions with other supplements and medications.

EPO supplements are best taken with a meal. The average dose is 500 milligrams per day — if your supplement’s dosage is higher than this, make sure you confirm the dosage with your doctor before use.

When trying a new supplement, it’s best to start with a lower dose and gradually work your way up to the standard dose. If you experience an upset stomach or nausea after taking EPO supplements, decrease your dose or discontinue use.

Topical application

Unlike essential oils, EPO does not need to be diluted. But you do need to do a skin patch test to check for possible allergic reaction.

If you are using evening primrose essential oil, then you must dilute it in a carrier oil before doing a patch test or using.

To do a patch test:

  1. Rub a drop of the oil on the inside of your forearm.
  2. Cover the area with a bandage.
  3. If you don’t experience any irritation or inflammation within 24 hours, it should be safe to apply elsewhere.
  4. If you do experience irritation, wash the area with cold water and discontinue use.

After a successful patch test, you can proceed with a full application to your scalp and the roots of your hair.

To do this:

  1. Start with dry hair for maximum penetration into your hair follicle.
  2. You can heat the oil slightly by rubbing it between your palms before applying it directly to your head.
  3. Massage the oil into your scalp and deep into your hair.
  4. Let the oil sit on your hair for up to 30 minutes.
  5. Rinse it out with a gentle cream cleanser.
  6. Style or air dry as usual.

You could even mix the oil into your favorite shampoo. Just be sure to massage the mixture deep into your roots and scalp before you rinse.

If you’re looking for a pure oil, this one from Maple Holistics is a popular choice.

There are also premade shampoos that you can purchase in stores and online. Depending on your preference, you can opt for an EPO-only shampoo or look for something more holistic. Some have added ingredients, such as biotin and rosemary.

EPO is generally safe to use for short periods of time. It isn’t clear whether EPO is safe to use for the long term.

Still, it’s important to talk to your doctor before using EPO or any other alternative remedy. Although it’s safe for the average user, there’s still a risk of side effects or interactions.

You shouldn’t take EPO without your doctor’s approval if you:

  • are pregnant
  • are taking blood-thinning medications like warfarin (Coumadin)
  • have epilepsy
  • have schizophrenia
  • have a hormone-sensitive cancer, such as breast or ovarian cancer
  • have a scheduled surgery within the next two weeks

If you’re experiencing new or unexpected hair loss, see your dermatologist. They can assess your symptoms and discuss treatment options. Although EPO may be an option, you may also want to try a more reliable alternative treatment.

If you experience any unusual side effects when using EPO, stop taking it and speak with your doctor. Side effects to watch for include accelerated hair loss, breakouts at or around your hairline, and hair or scalp discoloration.