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How do I Determine the Appropriate Evening Primrose Oil Dosage?

By Jane Olcott
Updated Mar 03, 2024
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Determining the appropriate evening primrose oil dosage is usually a matter of first figuring out what exactly you’re trying to treat, then paying attention to the instructions for your weight and age. In most cases, you’ll want to divide the dose into two or three portions spread over a few hours in order to get the most benefit. It’s hard to overdose on this oil, but taking too much at once can lead to some rather unpleasant consequences. Commercially prepared tinctures usually come with usage instructions and dosage guides that can provide a good starting place. In order to get the best results, though, it’s usually a good idea to talk to a medical professional or other natural health expert about your own unique situation before beginning.

Get a Formal Diagnosis

Evening primrose oil, also known as Oenothera biennis, is an herbal remedy used in the treatment of numerous medical conditions. One of the most important things to do when trying to get the right dosage is to identify why exactly you’re using it. Skin allergies and eczema are some of the most common ailments people use the oil to relieve, but it’s also frequently recommended to pregnant women to reduce pregnancy-induced hypertension and to induce labor. It can be taken to relieve the symptoms of premenstrual syndrome, arthritis, breast cancer, and heart disease, too; experts sometimes also recommend it for diabetic neuropathy and chronic fatigue syndrome.

Even if the bottle or packet of oil has general dosing instructions, these instructions can’t possibly cover ever potential use of the product. Someone who is looking to relieve a skin allergy will probably need a different amount than a person suffering from breast cancer, for example, and there are usually different guidelines for pregnant women, too. Trying to self-treat with the oil for conditions you think you might have can also be dangerous, both in terms of taking an inappropriate amount and missing out on other care options. In most cases it’s a good idea to get a formal diagnosis from a qualified medical provider before you start taking the oil, and to discuss proper doses for your specific condition with that person.

Weight and Age Considerations

Another factor you should consider when determining the appropriate evening primrose oil dosage is the basic age of the person who will be treated with it. People who are in their teens or older should generally take a larger dose than young children. In most cases an adult should take 1 to 2 teaspoons (4.9 to 9.8 ml) daily, while a child should not take more than about 1 teaspoon (4.9 ml).

The weight of the person, whether child or adult, will also help you determine the exact dosage that is appropriate. Sometimes commercial packaging takes individual weight into account, but more often it just groups all adults together. This is often fine, but results can be improved and better tailored if you adjust things for the person’s general size.

Most experts recommend that a child should have a maximum daily dosage of about 0.5 teaspoon per 10 pounds of body weight (about 2.4 ml per kg). An adult with an average weight should take about 1.5 teaspoons (7.3 ml) daily. Lighter adults might take 1 teaspoon (4.9 ml), and heavier adults might need 2 teaspoons (9.8 ml). If the condition persists after initial treatment, the dosage may be gently raised.

Dosage Timing

Evening primrose oil is generally absorbed directly into the bloodstream, which improves its potency but can also limit the amount of time during which it is active in the body. In most cases, a daily dose should not be taken all at once but rather should be divided into thirds and taken throughout the day, each portion several hours apart. This can both improve the end results and avoid potential side effects.

Sensitivities and Side Effects

Allergic reactions to normal evening primrose oil dosages have not been widely reported, though they can happen in certain circumstances. Side effects are also generally mild. Taking an incorrect dosage, however, can make reactions and negative effects more likely. Too much of the oil can lead to seizures, headaches, nausea, and loose stools. Anyone who experiences these symptoms should generally stop taking the supplement and seek medical advice.

Potential drug interactions are also something to think about. Many pharmaceutical products can interact with herbs and natural tinctures like evening primrose oil in a way that causes great harm to the people taking both. Pharmacists in most places are trained to watch for problems with prescribed medications that people are taking, but they don’t always know about a person’s over-the-counter supplements. Before you start this or any other natural remedy regimen, it’s a good idea to talk with a doctor, pharmacist, or someone else who knows your drug history. Similarly, it isn’t usually a good idea to begin a pharmaceutical drug regimen while you’re taking evening primrose oil doses without an expert telling you it’s okay.

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Discussion Comments

By serenesurface — On Apr 14, 2014

The normal dose for evening primrose oil is 1000mg to 3000mg/day. Like the article said, the dose should be broken up into two or three doses. So 500mg twice a day or three times a day.

If the supplement is taken in liquid form, then obviously the doses are different. The liquid doses are usually much smaller but it can vary from product to product. The label should mention how much of the liquid is equivalent to how many milligrams of primrose oil.

By fify — On Apr 14, 2014

@fBoyle-- That's a good point.

I have two evening primrose oil supplements at home, one is 1300mg per soft gel and the other is 500mg per soft gel. The recommended dose for both is one to two times a day. But those doses are very different and may be too little or too much depending on who's taking it and their body weight. So it's probably best to ask a doctor for an accurate dose.

Since I'm short and thin, and have high sensitivity to all medications and supplements, I always take the lowest dose possible. So I take 500mg once a day and it works just fine for me.

By fBoyle — On Apr 13, 2014

If age and weight are important for determining the right dose, then why do evening primrose oil supplements recommend the same dose to all adults?

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