Educational information, not medical advice — ask your doctor or midwife.
Evening primrose is a yellow-flowered plant whose seed oil is sold in capsules. People take it for eczema, breast pain and menopause symptoms. Good human trials have mostly not backed those uses.
The plant, Oenothera biennis, came from North America. It spread across Europe and now grows wild on sand, rubble and roadsides. In German it is called Nachtkerze, and the old root crop was known as Rapontika.
Almost every product is oil pressed from the tiny seeds. The selling point is a fat called gamma-linolenic acid, or GLA. The body makes only small amounts of it on its own.
Long use in European folk medicine is not proof that it works. It is also not proof that it is safe. The rest of this page keeps those two questions apart.
Most people who take the oil notice nothing. A smaller group report mild stomach upset or headache. The main safety issues are bleeding risk and use near birth, covered further down.
The proposed mechanism sounds sensible, but it has not produced clear results in people.
The oil is rich in GLA. In the body, GLA is changed into another fat called DGLA. In lab work, DGLA feeds the making of signals that appear to calm swelling.
The old theory was that people with eczema handle dietary fats poorly. Topping up GLA was meant to fill that gap. Blood tests do show that taking the oil raises DGLA levels.
What has not followed is a clear benefit. In trials of eczema and cyclical breast pain, the oil groups did about as well as dummy capsules. So the step from blood chemistry to a change you can feel is not established.
A second idea involves prostaglandins, which are hormone-like signals. In animal and cell studies, shifting these signals changes pain and swelling. Whether that happens in the skin or breast of a person taking capsules has not been shown.
For use near the end of pregnancy, the claim is that the oil softens the cervix. The evidence here is small and mixed. Some studies suggest no help, and some raise concerns about longer labour.
Softgel capsules of cold-pressed seed oil are by far the most common form.
- Softgel capsules: usually 500 mg or 1,000 mg of oil each. - Bottled liquid oil: taken by spoon or added to food. - Topical oil and creams: rubbed on dry or itchy skin.
- Vaginal capsules: sold for use near the end of pregnancy. This use needs a midwife or doctor, and is not for self-care. - Dried leaf or root: used in old European folk practice, now rare.
The oil goes off quickly when warm. Reliable products are cold-pressed, kept in dark packaging and given an expiry date. A rancid, fishy or sharp smell is a reason to throw a bottle out.
Capsule strength on the front of a pack is the weight of the oil, not of GLA. A 1,000 mg capsule holds roughly 80 to 100 mg of GLA. Checking the GLA figure on the back is the only way to compare brands.
Evening primrose reached Europe from North America in the 1600s, first as a garden and food plant.
The fleshy first-year root was boiled and eaten. German speakers knew it as Rapontika or Schinkenwurz, named for its pink, ham-like colour. It was grown as a minor vegetable in parts of Germany and Britain.
European folk healers later used leaf poultices on bruises and sore skin. Leaf teas were given for coughs and stomach complaints. These uses were recorded in household books rather than tested.
The modern story starts in the 1970s. Chemists found that the seed oil carried GLA, which was then rare in food oils. Companies built eczema and breast pain products around it.
In the UK, two prescription medicines based on the oil were licensed for eczema and breast pain. Both licences were withdrawn in 2002 after reviews found the benefit was not there. The oil stayed on sale as a supplement.
Stop taking it and get medical advice if you notice any of these:
- Unusual bruising, nosebleeds or bleeding that will not stop - Black or tarry stools, or blood when you are sick - A seizure, or a blackout you cannot explain - A spreading rash, swelling of the face, lips or throat, or trouble breathing; this is an emergency, so call emergency services - Breast pain that is new, one-sided, or comes with a lump - Eczema that is weeping, crusted or getting worse
Also see a doctor if nothing has improved after about three months. Tell any surgeon, dentist or midwife that you take it.
In the UK and the EU it is sold as a food supplement, not a medicine. Two UK prescription products for eczema and breast pain lost their licences in 2002 after reviews found no clear benefit. In the US it is a dietary supplement, and the FDA does not check it for effect before sale.
Evidence grades and traditional-use labels are explained in our methodology. Nothing here is medical advice.
What it is typically used for, usual dose, cautions, and the study behind it where real trial data exists.
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