What is Evening Primrose Oil?
Evening primrose oil (EPO) is a popular supplement extracted from the seeds of the evening primrose plant (Oenothera biennis), which is native to North and South America [1.4.5]. The oil is a rich source of omega-6 fatty acids, particularly linoleic acid and gamma-linolenic acid (GLA) [1.7.6]. GLA is converted in the body into substances like prostaglandins, which have anti-inflammatory effects [1.7.3, 1.7.6]. Historically, Native Americans used parts of the plant for various ailments, including soothing skin inflammation and treating gastrointestinal issues [1.4.3, 1.4.5]. Today, people use EPO for conditions like premenstrual syndrome (PMS), eczema, breast pain, and menopause symptoms, though scientific evidence supporting many of these uses is still developing [1.4.5, 1.7.3].
The Link Between Evening Primrose Oil and Diarrhea
The most frequent side effects associated with taking evening primrose oil orally are mild and gastrointestinal in nature [1.3.4]. Several sources confirm that diarrhea, along with upset stomach, nausea, loose stools, and abdominal pain, is a possible side effect [1.2.1, 1.2.2, 1.3.7].
Why does this happen? The high fatty acid content in the oil can act as a lubricant in the digestive system. For some people, especially those not accustomed to a high intake of certain oils, this can lead to faster transit times and looser stools. Some reports suggest that stomach pain and diarrhea may be an indication that the dosage is too high [1.2.3]. The body's reaction can vary greatly from person to person. While some may experience no issues, others are more sensitive to these effects.
Understanding Dosage and Minimizing Side Effects
For most people, evening primrose oil is likely safe when taken in doses up to 6 grams daily for up to one year [1.2.4, 1.3.6]. Side effects like diarrhea are typically mild and may resolve on their own [1.3.2]. To minimize the risk of gastrointestinal distress, experts suggest a few strategies:
- Start with a low dose: Gradually introducing EPO to your diet can help your system adjust and reduce the risk of side effects [1.6.2]. You might start with 500mg to 1,000mg per day and slowly increase if needed.
- Take it with food: Taking the supplement with a meal can help buffer its effects on the stomach and may reduce nausea and discomfort [1.6.1].
- Split the dose: Instead of taking a large dose at once, splitting it into two or three smaller doses throughout the day may be easier on your digestive system [1.6.5].
If symptoms like diarrhea persist or are severe, it's important to stop taking the supplement and consult a healthcare provider [1.6.2].
Comparison of Common Omega-6 Sources
Evening primrose oil is not the only source of GLA. Borage oil and black currant seed oil are other alternatives. Here’s how they compare:
| Feature | Evening Primrose Oil (EPO) | Borage Oil | Black Currant Seed Oil |
|---|---|---|---|
| GLA Content | 8-10% [1.8.2] | ~20-23% [1.8.2, 1.8.3] | ~15-20% |
| Common Uses | PMS, skin health, mastalgia [1.4.5] | Rheumatoid arthritis, eczema [1.8.2] | Skin health, inflammation |
| GI Side Effects | Nausea, diarrhea, upset stomach [1.2.4] | Similar to EPO, generally mild | Similar to EPO, generally mild |
| Other Notes | Most studied for PMS symptoms. | Highest concentration of GLA. | Contains omega-3 (SDA) as well. |
Potential Benefits and Other Considerations
Despite the potential for side effects, many people take EPO for its purported health benefits, which are linked to its GLA content. It is most commonly used for:
- Skin Health: Some studies and user reports suggest EPO can help with inflammatory skin conditions like eczema by reducing itching and redness, though larger reviews have found it no more effective than a placebo [1.7.1, 1.7.6].
- Hormonal Balance: EPO is widely used to alleviate symptoms of PMS and menopause [1.7.4]. Some research suggests it can reduce the severity of hot flashes and breast tenderness associated with the menstrual cycle [1.7.6].
- Arthritis: Due to its anti-inflammatory properties, some people use EPO to help manage the pain and stiffness of rheumatoid arthritis [1.7.6].
Important Precautions: EPO is not suitable for everyone. Individuals with bleeding disorders, epilepsy, or schizophrenia should avoid it [1.4.2, 1.5.1]. It can increase the risk of bleeding and should be stopped at least two weeks before any surgery [1.5.1]. It may also interact with medications like blood thinners (e.g., Warfarin), certain drugs for schizophrenia, and some HIV treatments [1.4.2, 1.5.2]. Always consult with a doctor before starting any new supplement, especially if you are pregnant, breastfeeding, or have a pre-existing health condition [1.4.5].
Conclusion
So, does evening primrose give you diarrhea? Yes, it is a known and relatively common side effect, though it is usually mild and often dose-dependent [1.2.3, 1.2.4]. While EPO offers potential benefits for skin and hormonal health due to its GLA content, it's crucial to be aware of the possible digestive issues. By starting with a low dose, taking it with food, and being mindful of your body's reaction, you can often mitigate these side effects. However, given the potential for more serious risks and drug interactions, consulting with a healthcare professional before adding evening primrose oil to your regimen is always the safest course of action [1.4.5].
