Evening Primrose Oil: Benefits for Women
Evening primrose oil is extracted from the Oenothera biennis wildflower, native to North America. Brought to Europe in the 1600, it has been used for medicinal purposes for centuries.
Famously used by midwives to encourage cervical ripening and shorten labor, evening primrose oil is also used for the treatment of PMS, menopausal symptoms, breast pain, and other ailments.
But does it actually work? Or is it just the placebo effect we are experiencing?
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Evening primrose oil is a rich source of essential fatty acids, such as linoleic acid and gamma-linolenic acid (1). Because of this, it is thought to have numerous health benefits.
It is popular among women for many reasons. The potential benefits for women include:
May help against PMS
May help against IBS at onset of menstruation
May help against breast pain
Fibroadenoma management
May reduce hot flashes
Encourage cervical ripening
Help reduce oedema
Very few and mostly small studies have been done to investigate these claims. Most of these claims are based on subjective opinions, and very little objective scientific evidence.
Evening primrose oil has shown potential in managing the symptoms of Premenstrual Syndrome (PMS) in women. PMS is a condition characterised by various physical, emotional, and behavioural symptoms experienced before menstruation. These symptoms can include anxiety, depression, acne, fatigue, headaches, and more.
One meta-analysis from 1996, confirmed the safety of daily doses ranging from 3 to 6 grams of evening primrose oil for individuals with PMS (2). Because of the small size of the studies included, they did not manage to conclude if the oil is effective against PMS symptoms.
A more recent study, compared the effects of gamma-linoleic acid (GLA), found in evening primrose oil, to a placebo (3). The group receiving GLA experienced reduced PMS symptom severity and duration, especially when it comes to irritability.
Additionally, a randomised placebo-controlled trial investigated the effects of primrose oil on women diagnosed with PMS (4). After three months of 1.5 g oil supplements, the group taking the oil reported improvements in PMS symptom severity.
Many women experience IBS symptoms around the onset of their menstruation. Primrose oil may be beneficial for women experiencing an upset stomach, and other related symptoms around that period (5).
It may promote the synthesis of anti-inflammatory prostaglandins and in this way help improve symptoms of IBS (6).
Generally speaking, it should take at least 2 to 3 months to notice improvement, although many people do not notice such beneficial effects at all (7).
Many people claim that primrose oil has helped to calm down their gut around the onset of menstruation. But we don’t have convincing quality clinical trials available, to back up these claims.
Evening primrose oil could help alleviate breast pain, also known as mastalgia.
Mastalgia can be categorized as cyclical and non-cyclical. Cyclical mastalgia is normally linked to hormonal changes during the menstrual cycle.
Several clinical trials have investigated the efficacy of evening primrose oil in managing mastalgia:
In one study, 100 women with mastalgia received either danazol or evening primrose oil for three months (8). Both treatments showed similar effectiveness, but the primrose group reported less adverse effects.
A study on women with cyclical mastalgia did not show a significant reduction in pain for the groups, treated with either evening primrose oil, vitamine E, or both (9). Interestingly, all groups that received treatment had less breast pain, compared to placebo. This shows that both primrose oil and vitamin E could have beneficial effects against breast pain.
But not all studies show these promising results:
In a large study, 555 women with mastalgia received combinations of gamma-linolenic acid, antioxidants, and placebo. All four groups, including placebo, showed improvement in breast pain, with no significant difference between them (10).
It is hypothesised that evening primrose oil may be used in the treatment of fibroadenomas - noncancerous tumours that are normally painless.
The exact cause of fibroadenomas is unknown, although hormones may play a role. In many cases, no treatment is necessary, but some patients opt for surgical removal of the lumps.
A clinical study investigated the effects of evening primrose oil on women with fibroadenoma. 39 participants received either evening primrose oil, or a placebo, for 6 months (11).
Surprisingly, despite positive feedback from patients, there was no significant difference in tumour size between the two groups.
The supplemented group had slightly more improvement (52%), compared to the placebo (42%), but the results were not significant.
What this means:
Evening primrose oil does not look like an effective fibroadenoma treatment.
But it is very difficult to get statistically significant results from such a small study. Large-scale research is needed to explore the effectiveness of this oil in fibroadenoma management.
Evening primrose oil is a popular alternative medicine for the managment of menopausal symptoms (12).
One of the most common symptoms of menopause are hot flashes.
In a study with 56 menopausal women, 500 mg evening primrose oil capsules were compared to a placebo (13).
Although the reduction in hot flash severity was slightly higher in the evening primrose oil group (42% versus 32% in the placebo group), the difference was not statistically significant. This is probably because the small sample size of the study makes it more difficult to have statistically significant results.
However, women taking the supplement reported improvements in social activities, sexuality, and relationships.
Despite these limitations, the findings suggest that this oil may offer some relief for menopausal women. Further research on a larger scale is necessary to confirm if this really is the case.
Evening primrose oil was widely used in the past by midwives to speed up cervical ripening and shorten labour time (15).
A study that investigated the effects of primrose oil on pregnancy, found that it does not significantly decrease the length of pregnancy or labour (16). What is more, the study suggested that using evening primrose during pregnancy could increase the risk of complications.
A recent clinical trial also found that the oil is not effective in promoting cervical ripening or shortening the duration of labour (17).
There are some smaller studies though, that do suggest this oil could be beneficial for cervical ripening (18).
There is a lot of uncertainty if taking evening primrose oil during pregnancy is safe or effective. Therefore, it is not recommended to use it during this time (14).
Primrose oil may help against oedema during pregnancy.
In a placebo-controlled clinical trial, pregnant women who received a combination of evening primrose and fish oil, containing beneficial fatty acids such as GLA, EPA, and DHA, had a lower occurrence of oedema compared to the placebo group (19).
The group receiving the evening primrose and fish oil mixture reported an incidence of oedema of 13%, whereas the placebo group had a higher incidence of 29%.
These findings suggest that the combination of evening primrose and fish oil, with their beneficial components such as GLA, EPA, and DHA, may lower the risk of oedema in pregnant women.
This oil is generally well tolerated by most people. But not everyone reacts to it the same (20). Uncommon side effects of include:
nausea
feeling full
symptoms related to indigestion
headache
upset digestive system
Rare side effects include:
inflammation
allergic reactions
rashes
abdominal pain
higher body temperature
Seizures
There is a chance that Primrose oil could increase the incidence of seizures, so people with epilepsy and schizophrenia should consult a doctor if they consider using it.
Increased bleeding
If you have conditions that make you prone to bleeding, or if you're taking anticoagulants or anti platelet medications, it's important to seek medical advice before considering the use of primrose oil. This supplement has the potential to increase the risk of bleeding, so consulting with a doctor is crucial to ensure your safety.
Evening primrose oil has been used for centuries to treat various ailments. People take it for many reasons including:
ease PMS symptoms
reduce hot flashes and other menopausal symptoms
reduce breast pain
reduce labour time
Most of the evidence we have that this oil works is very subjective and based on people's personal experience.
Most objective studies either say it is not effective at all, or are too small to be able to conclude anything with certainty.