Evening primrose oil has a long history as a natural health remedy. It’s been hailed as everything from a hair loss solution to a cure for acne. But what is it exactly?

Evening primrose (Oenothera biennis), sometimes called “the night willow herb,” is a flowering plant. It’s also a night owl, blooming at sunset instead of sunrise. The oil pressed from its seeds, aka evening primrose oil (EPO for short), is a gentle carrier oil.

It can be ingested, applied as a topical balm, or blended with other carrier oils in skin care formulations.

The reason EPO just might work is that it’s full of gamma-linolenic acid (GLA), an omega-6 fatty acid that reduces inflammation.

Here are 13 science-supported benefits of adding EPO to your daily routine.

Natural health and fertility sites often recommend EPO to accelerate babymaking. The idea is that the GLA in the oil improves cervical mucus and egg quality just like other omega fatty acids do.

More research is needed, but if you’re trying to get pregnant, ask your doctor about EPO. Makes sense to add these healthy fats to your diet.

Hormone-related sweats and hot flashes are the worst, so we’re here for any science-backed remedies. EPO to the rescue!

A 2013 study found that menopausal women who took daily EPO supplements for 6 weeks reported fewer hot flashes — and the ones they did have were way less fiery. Even better? The women said cooling their hot flashes also improved lifestyle factors like social interactions and lovemaking.

Deal with breakouts on the reg? EPO could be your new BFF. The GLA ingredient soothes inflammation while the oil itself adds a dewy glow.

In one promising study, 45 people with acne had fewer lesions after taking GLA.

Some research suggests EPO also soothes cheilitis, a swollen, red rash around your lips caused by isotretinoin (aka Accutane, a common anti-acne drug).

The research is thin, but EPO fans say it soothes eczema.

In one practically retro study (1991), results indicated that the GLA in EPO nourishes the top layer of skin, which gets inflamed by eczema.

Unfortunately, a 2013 review of 27 studies concluded that popping EPO supplements isn’t any more effective than taking a placebo. So this benefit might be a draw.

Skin feeling a little “meh” these days? EPO’s healthy helping of GLA is known to improve elasticity, firmness, moisture — all the good stuff.

A 2005 study suggests taking EPO boosts your body’s stores of skin-nourishing GLA (a fatty acid your skin can’t produce on its own). A 2011 study affirmed this when participants with dry skin noticed an improvement after noshing on GLA-rich foods.

Research on rats instead of humans should be taken with a grain of salt, but here’s the tea: In a 2014 study, rats that dosed on EPO experienced reduced blood cholesterol and lower levels of inflammation.

Since heart disease is often linked to inflammation, EPO could indirectly reduce your risk of heart disease. More research with humans is needed, but it’s something you could discuss with your doctor.

The jury’s still out on this one, but some studies indicate that EPO could lower blood pressure.

In one study, participants who took EPO had a slightly higher systolic blood pressure. Researchers said results were “intriguing,” but noted there were too many factors to prove a causal relationship.

Another review of studies revealed that evidence of EPO reducing high blood pressure is too limited to recommend it in a clinical setting. It is possible that EPO might interfere with medications.

There’s dated research that EPO could relieve PMS symptoms like irritability, moodiness, and even bloating. Again, it’s because of GLA, which triggers a chemical reaction that seems to prevent PMS.

A 2010 study further affirmed that supplements containing EPO (but also packed with vitamin B-6 and vitamin E) helped with PMS. Of course, we don’t know whether the EPO or other vitamins deserve the credit.

Your emotions might not be the only thing that gets a little sensitive when the crimson tide rolls. If your boobs get achy on the reg, EPO could help.

Research suggests the GLA in EPO reduces inflammation, which causes your monthly boob pain. The same study includes daily doses of vitamin E, so it’s tough to say whether it was the combo or EPO alone that helped.

You already know the GLA in EPO is anti-inflammatory, which means it has the potential to soothe all kinds of aches — boob pain, joint pain, and so on.

A review of the research further backed up claims that a dose of EPO a day keeps arthritis away. Bonus — it didn’t seem to cause any side effects!

Health conditions like diabetes often come with an unhelpful side of nerve pain, tingling, weakness, and sensitivity to extreme temps. The good news is that GLA soothes damaged nerve symptoms.

In a 2014 study of 70 people with diabetes, participants who took EPO and vitamin E for a year experienced a reduction in nerve pain.

Whether you’re losing hair by the handful or are looking to give your locks a little extra “oomph,” EPO could help.

Research is still limited, but the arachidonic acid in EPO has been known to boost your hair growth potential. And again, GLA’s anti-inflammatory powers could help make your scalp a happier, healthier environment for your hair.

You’ll find EPO in heaps of weight loss supplements, but what does science say? Not much, TBH.

As you know by now, EPO contains GLA, which is an omega-3 fatty acid. Research suggests balancing your omega-3 and omega-6 intake reduces your risk of obesity. So yeah, in a way, keeping those fatty acids balanced is part of maintaining a healthy weight.

But claims beyond that just don’t hold weight (pun intended!). Even older studies suggest EPO doesn’t make a difference in weight loss efforts.

There’s been enough research on EPO to consider it generally safe for short-term use. But remember — supplements are a pretty unregulated industry. They don’t fall under FDA monitoring, so there could be issues with quality and dosing suggestions.

As for side effects, every rose has its thorn, right? Here are the most common:

  • headache
  • soft or sludgy poop
  • upset stomach or stomach pains

If you’re allergic to other flowering plants or oils, be cautious about ingesting EPO. Watch for these signs of an allergic reaction:

  • swelling or redness in your hands or feet
  • rash
  • trouble breathing
  • whistling cough or other wheezing sounds

Evening primrose oil (EPO) has been used as a remedy for inflammation and several other skin and health conditions for years. More research is necessary to recommend it as a clinical treatment.

EPO combined with vitamin E could alleviate symptoms, but it shouldn’t replace meds recommended by your doctor.

Always use the lowest dose possible to reduce your risk of side effects. Talk to your doctor about the EPO method and dosage best for your conditions.