(Oenothera spp.)

Natural Standard® Patient Monograph, Copyright © 2014 (www.naturalstandard.com). All Rights Reserved. Commercial distribution prohibited. This monograph is intended for informational purposes only, and should not be interpreted as specific medical advice. You should consult with a qualified healthcare provider before making decisions about therapies and/or health conditions.

Common Brand Name(s)

Background

Native Americans traditionally considered the evening primrose plant’s seeds, leaves, and roots to be a food. They also used the plant to treat bruises or wounds, hemorrhoids, stomach problems, and sore throats.

Oil extracted from evening primrose (Oenothera biennis) plant seeds consists of a high amount of unsaturated fatty acids. These fatty acids include omega-6 fatty acids, linolenic acid, and gamma-linolenic acid (GLA). GLA has been licensed for treating breast pain and eczema in numerous countries.

Evening primrose oil (EPO) has been studied for several disorders, particularly those affected by metabolic products of essential fatty acids. There is good scientific evidence to support EPO for eczema treatment.

Related terms

(+)-catechin, aceite de onagra (Spanish), arachadonic acid (AA), cis-linoleic acid, dihomo-gamma-linolenic acid (DGLA), Echte Nachtkerze (German), ellagic acid, EPO, fever plant, gallic acid, gamma-linolenic acid (GLA), gamolenic acid (GLA), herbe aux anes (French), Huile D’Onagre (French), kaempe natlys, King’s Cureall, la belle de nuit (French), linoleic acid (LA), nachtkerzenol (German), night willow-herb, Oenothera biennis L., Oenothera communis Leveill, Oenothera graveolens Gilib, Oenothera paradoxa, omega-6 essential fatty acid, Onagra biennis Scop, Onagraceae (family), Onogra vulgaris, onagre bisannuelle, pentagalloylglucose, penta-O-galloyl-beta-D-glucose, primrose oil, procyanidins, scabish, Spach, stella di sera, sun drop, Teunisbloem (Dutch), unsaturated fatty acids.

According to secondary sources, Epogam (40mg GLA and 10mg vitamin E) and Efamast (gamolenic acid) had their product licenses withdrawn October 7, 2002, following a review by the MCA/Committee on Safety of Medicines (CSM) of all the relevant information. It was determined that the information available did not support the standard of efficacy required for the authorization of these products as medicines for the treatment of eczema and mastalgia.

Combination product examples: Bronchicum® Tropfen (thyme and primrose), Bronchipret® TP FCT (thyme and primrose), Bronchicum® Elixir S (thyme and primrose).
Zestra® (borage seed oil, evening primrose oil, angelica root extract, and coleus extract)

The combination compound was called IOVE and was composed of 60mg isoflavones, 440mg primrose oil (consisting of 9-10% gamma linolenic acid (GLA)), and 10mg vitamin E.

Dosing

The below doses are based on scientific research, publications, traditional use, or expert opinion. Many herbs and supplements have not been thoroughly tested, and safety and effectiveness may not be proven. Brands may be made differently, with variable ingredients, even within the same brand. The below doses may not apply to all products. You should read product labels, and discuss doses with a qualified healthcare provider before starting therapy.

Adults (18 years and older)

For alcohol intoxication, six 500 milligram capsules of EPO have been taken by mouth daily for one week.
For bronchitis, one tablet of a thyme-primrose combination product (Bronchipret® TP FCT) has been taken by mouth three times daily for 11 days. Two other combination products, Bronchicum® Elixir S and Bronchcium® Tropfen, have been taken by mouth in doses of 6 x 5 milliliters of fluid or 5 x 1 milliliter of drops for 7-9 days.

For breast pain (mastalgia), 1-3 grams or 2.4 milliliters of EPO, 1-6 capsules of EPO, or 240-320 milligrams of GLA (Efamast®, Efamol®) has been taken by mouth 1-3 times daily for up to six months.
For heart health, 10-30 milliliters of EPO (Efamol®) has been taken by mouth daily for four months. Additionally, 3 grams of a linoleic-GLA combination has been taken by mouth for two months.

For childbirth (labor induction or cervical ripening), one EPO capsule has been taken by mouth three times daily for one week.
For diabetes, two Efamol® capsules, containing 45 milligrams GLA and 360 milligrams LA (linoleic acid), have been taken by mouth daily for four months and then increased to four Efamol® capsules daily for an additional eight months.

For diabetic neuropathy (nerve damage), 360-480 milligrams of GLA have been taken by mouth daily for up to 12 months.
For dry eyes, six EPO capsules (Qarma™, Equazen™) have been taken by mouth daily for six months.

For eczema (atopic dermatitis), 1-4 EPO capsules (360 milligrams linoleic acid and 40-45 milligrams GLA per capsule) have been taken by mouth twice daily for up to 12 weeks. Additionally, 4-12 capsules (500 milligrams EPO per capsule) have been taken by mouth daily in two divided doses for up to five months (Efamol®). EPO doses have ranged from 0.5 grams-0.5 grams/kilogram taken by mouth for 3-16 weeks. A dose of 1 milliliter of 20% EPO has been applied to the skin twice daily for up to four months. EPO has been applied to the arms for two weeks.

For high cholesterol, four capsules, containing 0.3 grams EPO, have been taken by mouth three times daily for 16 weeks. Additionally, 1.5-2 grams of EPO has been taken by mouth twice daily for 1-3 months.
For liver cancer, 36 capsules, containing 500 milligrams EPO per capsule (Efamol®) daily (totaling 1.44 grams GLA daily) have been taken by mouth.
For liver disease, 2 grams of Efamol® has been taken by mouth twice daily for 12 weeks.

For lupus, 5 grams of EPO has been taken by mouth daily.
For premenstrual syndrome (PMS), 500-6,000 milligrams of EPO or 6-12 capsules EPO have been taken by mouth 1-4 times daily for up to 10 months (Efamol®).
For rheumatoid arthritis, 540-6,000 milligrams of EPO and 20-30 milliliters of EPO have been taken by mouth daily for 3-12 months.

For schizophrenia, 6-8 grams of EPO has been taken daily in divided doses. Eight Efamol® capsules have been taken by mouth daily for two to four months.
Children (younger than 18 years)

For eczema (atopic dermatitis), 1-12 capsules (500 milligrams EPO per capsule) have been taken by mouth daily in single or divided doses for up to five months, at a maximum of 0.5 grams/kilogram daily.
For diabetes, 2-4 EPO capsules (Efamol) have been taken by mouth daily for 4-8 months.

Safety

The U.S. Food and Drug Administration does not strictly regulate herbs and supplements. There is no guarantee of strength, purity or safety of products, and effects may vary. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare provider before starting a new therapy. Consult a healthcare provider immediately if you experience side effects.

Allergies

Allergy or sensitivity reactions to evening primrose oil (EPO), although rare, have been reported. People who are allergic to EPO, plants in the Onagraceae family, gamma-linolenic acid (GLA), or other ingredients or constituents in EPO should avoid its use.

Inflammation on the hands and face has been reported.

A healthy pregnant female, who consumed raspberry leaf tea and thirteen 500 milligram EPO capsules, had a ripened cervix and shorter duration of childbirth. After delivery, skin lesions were experienced by the newborn infant, which were resolved by five days after delivery.

Side Effects and Warnings

Evening primrose oil is likely safe when taken by mouth in suggested doses for up to one year for premenstrual syndrome (PMS), breast pain, or eczema (atopic dermatitis).

Evening primrose oil may cause low blood pressure. Caution is advised in people taking drugs or herbs and supplements that lower blood pressure.
Evening primrose oil may increase the risk of bleeding. Caution is advised in people with bleeding disorders or taking drugs that may increase the risk of bleeding. Dosing adjustments may be necessary.
Use cautiously in people with seizure disorders or mania. Use cautiously in pregnant or breastfeeding women.

Use cautiously in people taking agents for convulsions or depression, agents for the brain, central nervous system (CNS) stimulants, or people undergoing anesthesia.
Avoid in people with an allergy or sensitivity reaction to evening primrose oil (EPO). People who are allergic to EPO, plants in the Onagraceae family, gamma-linolenic acid (GLA), or other ingredients or constituents in EPO should avoid its use.

Evening primrose oil may also cause abdominal pain, acidity, acne, altered immune system function, anxiety, belching, bloating, cellulitis (skin infection), cervix ripening, colic, constipation, cough, cramping, crying, decreased or increased duration of childbirth, depression, diarrhea, difficulty swallowing, dizziness, dryness of mucous membranes, eczema, fullness, gas, gastrointestinal adverse effects, headache, heartburn, increased bleeding time or decreased platelet aggregation, increased risk of inflammation, indigestion, irregular menstruation, irritability, itchy and fatty skin, loose stools, musculoskeletal adverse effects, nausea, nervous system adverse effects, pneumonia, reproductive system adverse effects, respiratory system adverse effects, seizures or lowered seizure threshold, short temper, skin lesions in newborns, skin rash, slower dilation during childbirth, stomachache, tension, vivid dreams, vomiting, weight gain, or worsening mania.

Pregnancy and Breastfeeding

There is a lack of sufficient data on the use of EPO during pregnancy or lactation.
A study has reported women taking EPO by mouth to have a longer labor, slower dilation rate, prolonged rupture of membranes, use of oxytocin, and arrest of descent.
Females receiving Efamol® for eight months of lactation had increased total fat and essential fatty acids in breast milk. Evidence of adverse effects was lacking in breastfed infants.

A healthy pregnant female, who consumed raspberry leaf tea and thirteen 500 milligram EPO capsules, had a ripened cervix and shorter duration of childbirth. After delivery, skin lesions were experienced by the newborn infant, which were resolved by five days after delivery.

Interactions

Interactions with Drugs
Evening primrose oil may lower blood sugar levels. Caution is advised when using medications that may also lower blood sugar. People taking drugs for diabetes by mouth or insulin should be monitored closely by a qualified healthcare professional, including a pharmacist. Medication adjustments may be necessary.

Evening primrose oil may increase the risk of bleeding when taken with drugs that increase the risk of bleeding. Some examples include aspirin, anticoagulants (“blood thinners”) such as warfarin (Coumadin®) or heparin, anti-platelet drugs such as clopidogrel (Plavix®), and non-steroidal anti-inflammatory drugs such as ibuprofen (Motrin®, Advil®) or naproxen (Naprosyn®, Aleve®).

Evening primrose oil may interfere with the way the body processes certain drugs using the liver’s “cytochrome P450” enzyme system. As a result, the levels of these drugs may be increased in the blood, and may cause increased effects or potentially serious adverse reactions. People using any medications should check the package insert, and speak with a qualified healthcare professional, including a pharmacist, about possible interactions.

Evening primrose oil may increase the amount of drowsiness caused by some drugs. Examples include benzodiazepines such as lorazepam (Ativan®) or diazepam (Valium®), barbiturates such as phenobarbital, narcotics such as codeine, some antidepressants, and alcohol. Caution is advised while driving or operating machinery.
Evening primrose oil may cause low blood pressure. Caution is advised in people taking drugs that lower blood pressure.

Evening primrose oil may also interact with agents for arthritis, cancer, or obesity; agents for the brain, skin, stomach, or intestines; agents that lower cholesterol; alcohol; aldose reductase inhibitors; anesthetics; antibiotics; anticonvulsants; antidepressant agents such as monoamine oxidase inhibitors (MAOIs) or selective serotonin reuptake inhibitors (SSRIs); anti-inflammatory agents; antipsychotics; antiviral agents; beta-blockers; celecoxib; CNS depressants or stimulants; corticosteroids; COX-2 inhibitors; Faslodex®; phenothiazines; seizure threshold-lowering agents; tamoxifen; or vincristine.

Interactions with Herbs and Dietary Supplements
Evening primrose oil may alter blood sugar levels. Caution is advised when using herbs or supplements that may also alter blood sugar. Blood glucose levels may require monitoring, and doses may need adjustment.

Evening primrose oil may increase the risk of bleeding when taken with herbs and supplements that are believed to increase the risk of bleeding. Multiple cases of bleeding have been reported with the use of Ginkgo biloba, and fewer cases with garlic and saw palmetto. Numerous other agents may theoretically increase the risk of bleeding, although this has not been proven in most cases.

Evening primrose oil may interfere with the way the body processes certain herbs or supplements using the liver’s “cytochrome P450” enzyme system. As a result, the levels of other herbs or supplements may become too high in the blood. It may also alter the effects that other herbs or supplements possibly have on the P450 system.

Evening primrose oil may increase the amount of drowsiness caused by some herbs or supplements.
Evening primrose oil may cause altered blood pressure. Caution is advised in people taking herbs or supplements that alter blood pressure.

Evening primrose oil may also interact with anesthetics; antibacterials; anticonvulsants; antidepressants such as monoamine oxidase inhibitors (MAOIs) or selective serotonin reuptake inhibitors (SSRIs); anti-inflammatories; antioxidants; antipsychotics; antivirals; CNS depressants or stimulants; COX inhibitors; herbs and supplements for arthritis, cancer, or obesity; herbs and supplements for the brain, skin, stomach, or intestines; herbs and supplements that reduce cholesterol; seizure threshold-lowering herbs and supplements; thyme; vitamin C; zinc.

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