Black Seed Oil: Side Effects & Interactions

Black seed oil is supplemented for many health benefits, including lowered high blood pressure, improved blood sugar levels, weight management, reduced asthma symptoms, and brain function.  As with any supplement, …

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Written by: Jack Cincotta, MS
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Medical Review by: Daniel Powers, MS
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Black seed oil is supplemented for many health benefits, including lowered high blood pressure, improved blood sugar levels, weight management, reduced asthma symptoms, and brain function. 

As with any supplement, it’s important to understand if black seed is actually safe to take.

Thus, in this article, we’ll cover the complete safety profile and potential side effects of black seed oil, as well as possible interactions with medications and other important information.

nigella sativa oil side effects and safety

Black Seed Oil Overview:

Black seed oil is a dietary supplement which comes from the Black Cumin (Nigella sativa) plant, which is a shrub native to the Mediterranean, Southwest Asia, Northern Africa, and a few other areas. 

The flowers of Black cumin plants contain many black seeds (where the supplement gets its name from) which appear to have the highest concentration of bioactive compounds, including the most notable one, thymoquinone. 

Thymoquinone and other compounds are thought to deliver most of the health benefits of black seed, especially for promoting hair growth and supporting skin health.

Is Black Seed Oil Safe to Consume?

Yes, black seed oil is safe to consume for most individuals. Overall, clinical trials have shown that black seed is generally safe to consume and unlikely to cause side effects when taking black seed oil within the recommended dosage ranges.

Yet, no supplement is ever completely free of possible side effects. It’s always best to talk with your doctor before taking any dietary supplement, especially if you have chronic health conditions and/or take prescription medications.

Some individuals may experience elevated levels of liver and kidney enzymes, but this issue doesn’t seem to be significant for the vast majority of people. 

Is Black Seed Oil Safe?

Yes, black seed is safe for most individuals to take. Black seed oil may increase liver and kidney enzymes and should be used with caution in combination with certain medications. It is recommended that you speak with your doctor before adding any new supplements to your routine.

What Medications Should Not Be Taken With Black Seed Oil?

Black seed oil has several potential interactions with prescription medications, given that it exerts numerous unique effects in the human body.

Specifically, black seed oil may interact with:

  • Antihypertensives
    • Prinivil
    • Lopressor
    • Zestril
    • Norvasc
  • Anticoagulants:
    • Eliquis
    • Xarelto
    • Pradaxa
  • Immunosuppressants
  • Hypoglycemics/Antidiabetic Drugs
    • Ozempic
    • Trulicity
    • Amaryl
    • Metformin
  • Diuretics
    • Edecrin
    • Lasix
    • Lozide
  • Sedatives
    • Nembutal 
    • Xanax
    • Luminal
    • Valium
  • Serotonergic drugs, such as SSRIs
    • Celexa
    • Lexapro
    • Zoloft

This is not an exhaustive list. It’s important to talk with your doctor to ensure there are no interactions between black seed and whatever medication(s) you take.

Black Seed Oil Side Effects:

Black seed oil may have minimal side effects. Based on clinical research, the main possible side effects are:

  • Nausea
  • Bloating
  • Heartburn

There is also a slight increase in liver and kidney enzymes in some individuals. But overall, the magnitude of this, and all other side effects, is low, and black seed is deemed safe for most individuals.

How Much Black Seed Oil Should I Take?

Clinical research shows that the most effective dose of black seed oil is 5-10mL per day (or 1 to 3 grams of black seed in powdered/capsule form). 

Lower doses, such as 2.5mL or 250 to 500g of powder, have also been used successfully. So, this may be a good starting dose, especially for individuals who want to assess tolerance and side effects before building up the dosage.

Overall, it’s best to stay in these ranges in order to ensure safe usage and limit the chance of any possible side effects. 

Black Seed Oil Dosage:

Clinical research suggests that taking between 5mL and 10mL of black seed oil or 1g to 3g of black seed powder is an effective dosage.

When Should I Take Black Seed Oil?

The best time to take black seed oil for most people is in the morning and/or afternoon before meals, particularly for individuals looking for metabolic-related benefits, such as blood sugar and lipid regulation, and weight loss.

However, generally speaking, there isn’t one ideal time to take black seed for everyone. The exact time one takes doesn’t seem as important as the total dosage. Additionally, research shows that taking black seed oil just once or multiple times per day, so it is a rather versatile supplement. 

Overall, it’s best to simply pick one consistent supplement schedule and stick with that in order to help maintain consistency over the long term.

Should I Cycle Black Seed Oil?

Overall, cycling black seed oil seems unnecessary. In clinical studies, black seed oil has been used continuously for up to 6 months, so it doesn’t appear that cycling black seed is required or even recommended. 

With that said, it is always best to consult with your doctor or other healthcare practitioner to ensure that you maintain a safe and effective black seed oil supplementation regimen.

How Long Does it Take for Black Seed Oil to Work?

Black seed oil can exert some degree of benefit rather quickly, as some studies have shown benefits in as little as one to two weeks. 

However, to achieve the most benefits for most conditions, it seems best to take black seed consistently for around 8-12 weeks to get the most amount of benefits.

Also, the degree of benefits one receives also likely depends on other individual factors, such as age, current health status, severity of health condition(s), diet, and lifestyle.


Daily supplementation with black seed oil is thought to begin displaying health benefits in as little as one to two weeks.

Read More:

Below, we’ve put together several articles going over additional helpful information regarding black seed.

7 Benefits of Black Seed: Dosage & Safety

Best Black Seed Supplements | 2023 Complete Guide

The Best Time of Day to Take Black Seed Oil

• Black Seed Oil for Dogs

Black Seed Oil for Hair

Black Seed Oil for Herpes

nigella sativa side effects and interactions


Black seed oil is potentially effective for several health conditions, and it appears safe for the majority of individuals when used in the appropriate dosage of 5 to 15mL (or 1 to 3g of powder).

Yet, there are a few possible side effects, and black seed also has the chance to interact with several different classes of prescription medications. Thus, it’s necessary to consult with your doctor before supplementing with black seed oil. 

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About Jack Cincotta, MS

Jack has a Master of Science degree in Psychology and is also an AADP® Board Certified Holistic Health Practitioner and AFPA® Certified Holistic Health Coach. His passion is to help people develop optimal levels of health, particularly mental health.