Evening primrose is a wildflower that grows throughout the United States. Although Native Americans used the seeds for food and made poultices from the whole plant to heal bruises, evening primrose oil (EPO) has only recently been used as medicine. European settlers took the root back to England and Germany where it was eaten as food.
EPO is found in the plant's seeds, and is high in the essential fatty acid gamma-linolenic acid (GLA). Essential fatty acids, such as omega-6s found in EPO and omega-3s found in fish oil, are used as building blocks for a number of molecules in the body. Your body needs a balance of omega-6 and omega-3 fatty acids for good health. GLA is also found in borage oil and black currant oil.
Today, EPO is used to relieve PMS symptoms and some arthritis-related conditions, although scientific evidence to support these uses is lacking. The strongest evidence for EPO use is for treating eczema.
This article focuses on the seed from which EPO is extracted.
A circle of leaves grows close to the ground around evening primrose stems after the first year it is planted. Flowers bloom after sunset, June through September, or on overcast days during the second year. The leaves grow on both sides of the stem at alternating levels.
Oil is extracted from the seeds and prepared as medicine using a chemical called hexane. The seeds contain up to 25% essential fatty acids, including linoleic acid (LA) and gamma-linolenic acid (GLA). Both LA and GLA are omega-6 fatty acids. The body needs a balance of omega-6s and omega-3s (found in fish oil) to stay healthy. Most North Americans get too much omega-6 fatty acids in their diet. However, there are different types of omega-6 fatty acids. Some are healthier than others, such as those found in EPO.
Other sources of GLA include spirulina (a blue-green algae), borage, hemp, and black currant oils.
EPO is used mostly to relieve the itchiness caused by skin conditions, such as eczema and dermatitis. It is also used to ease breast tenderness from premenstrual syndrome (PMS) or other causes, and to help manage menopausal symptoms.
Eczema symptoms include redness and scaling in addition to itching. More than 30 human studies report the benefits of EPO for eczema and dermatitis. A study of 1,207 people found that EPO helped relieve symptoms from skin conditions, including itching, crusting, edema (fluid retention and swelling), and redness. EPO can be used in children and adults with skin conditions.
Many women throughout the world take EPO to reduce PMS symptoms, although scientific evidence is lacking. In one review of 10 studies that used EPO to treat PMS, only two were well designed. Both of those studies found that EPO had no effect on PMS symptoms. More research is needed.
Although a few studies have found that people with RA who took EPO felt better, the studies were hampered by poor design and high drop-out rates. Also, there wasn't any evidence that taking EPO actually helped slow down the joint damage that occurs with RA. People with RA should be treated with conventional medications to slow down or stop permanent joint damage.
One small study suggests that taking EPO may help reduce symptoms in some people with Raynaud's phenomenon. But the study found no difference in hand temperature between people who took EPO and those who took placebo. More studies are needed.
Diabetic peripheral neuropathy is a nerve condition where people with diabetes have numbness, tingling, pain, burning, or a lack of sensation in their feet and legs. Two studies have found that GLA may help reduce symptoms of diabetic neuropathy.
Although there is not a lot of scientific evidence, EPO is widely used to treat breast pain (mastalgia) in a number of European countries. A few studies have found that EPO seemed to help. But they were not well-designed studies. Other studies showed no benefit. More research is needed.
Preliminary studies suggest EPO may help alleviate the hot flashes that often accompany menopause. More research is needed.
EPO is available as an oil or in capsules. EPO products should be kept in the refrigerator and out of direct sunlight to prevent the oil from becoming rancid. Generally, high-quality EPO will be certified as organic by a reputable third party, packaged in light-resistant containers, refrigerated, and marked with a freshness date.
EPO should be standardized to contain 8% gamma-linolenic acid.
Ask your doctor before giving EPO to a child.
Speak to your doctor regarding dosing instructions.
EPO is generally safe when used in recommended dosages. Reported side effects are rare and mild, and include nausea, stomach pain, and headache. Stomach pain and loose stools may mean that the dose is too high.
DO NOT use omega-6 supplements, including GLA and EPO, if you have epilepsy or another seizure disorder because there have been reports of these supplements bringing on seizures.
DO NOT take EPO if you have bleeding problems or a blood disorder.
Pregnant and breastfeeding women should ask their doctors before taking EPO.
If you are currently being treated with any of the following medications, you should not use EPO without first talking to your doctor.
Blood-thinning medications (anticoagulants): EPO may raise the risk of bleeding, especially if you take blood thinners such as aspirin, warfarin (Coumadin), and clopidogrel (Plavix).
Blood pressure medications: EPO may lower blood pressure in some people, although researchers have not confirmed this link. If you take medications to treat high blood pressure, ask your doctor before taking EPO.
Phenothizines: People who take a class of medications called phenothiazines to treat schizophrenia should not take EPO because it may increase the risk of seizures.
Medications to control seizures: EPO may lower the threshold for seizures, so people who are prone to seizures should not take it.
Antidepressants: EPO may interact with some antidepressants, including selective serotonin uptake inhibitors, such as:
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