What Is Black Seed Oil?

Black seed oil is a supplement extracted from the seeds of Nigella sativa, a flowering plant that grows in Asia, Pakistan, and Iran. Black seed oil has a long history dating back over 2000 years.

Black seed oil contains the phytochemical thymoquinone, which can act as an antioxidant. Antioxidants detoxify harmful chemicals in the body called free radicals.

This article discusses the potential uses, risk factors, and side effects of taking the supplement.

Uses of Black Seed Oil

Supplement use should be individualized and vetted by a healthcare professional, such as a registered dietitian nutritionist, pharmacist, or doctor. No supplement is intended to treat, cure, or prevent a disease.

Although research on the health effects of black seed oil is relatively limited, there is some evidence that it may offer potential benefits. Here's a look at several key findings from available studies.

Type 2 Diabetes

Black seed oil may benefit some people with type 2 diabetes, according to a 2017 review published in the Journal of Pharmacopuncture.

Researchers reviewed four randomized, double-blind, placebo-controlled clinical trials with people who had taken black seed in the form of an oil, tea, or seeds. Results indicated that participants had a decrease in their fasting blood glucose. It is important to note that in most of the studies, black seed oil was consumed in addition to using oral diabetes medications, eating a healthy diet, and exercising.

A more recent study from 2020 aimed to evaluate the effect of black seed oil on inflammation, fasting blood glucose, and lipid profile in people with type 2 diabetes. The results also showed significant reductions in fasting blood glucose levels among those who received black seed oil capsules versus the placebo group.

Rheumatoid Arthritis

According to a small study published in Immunological Investigations in 2016, black seed oil may help manage rheumatoid arthritis (RA).

In this randomized, double-blinded placebo-controlled study, 43 women with mild-to-moderate RA took black seed oil capsules or a placebo every day for one month. Compared to the placebo group, those who used black seed oil reported reductions in:

• Arthritis symptoms (as assessed by a clinical rating scale)
• Blood levels of inflammatory markers
• The number of swollen joints

Allergies & Nasal Inflammation

Black seed oil shows promise for treating allergies. For instance, in a 2011 clinical trial with 66 people published in the American Journal of Otolaryngology, when participants used black seed oil for two weeks, it reduced nasal symptoms including:

• Nasal congestion
• Itchy nose
• Runny nose
• Sneezing

Another report published in 2018 analyzed data to determine if black seed oil could help treat sinusitis. Study authors concluded that the oil has multiple therapeutic effects, including:

• Anti-inflammatory
• Antioxidant
• Antihistaminic
• Immune-modulator (something that affects the immune system)
• Antimicrobial
• Analgesic

Obesity

Black seed oil may reduce risk factors in women who are obese, according to a study.

For the study, women consumed Nigella sativa oil or a placebo while following a low-calorie diet for eight weeks. At the study's end, the following levels had decreased by more in the group that took the Nigella sativa oil:

• Weight
• Waist circumference
• Triglyceride

Another eight-week study enrolled sedentary women with excess weight and looked at the combination of aerobic exercise with black seed oil supplementation. In the study, one group took black seed oil, and another took a placebo; both used aerobic exercise.

Researchers found that the treatment combination of diet, exercise, and black seed oil provided benefits, including lowering cholesterol levels and body mass index (BMI) compared to the placebo group. Still, the authors concluded that further studies with a larger sample size and diet assessment are needed.

Other Uses of Black Seed Oil

While black seed oil has been studied in human, lab, and animal studies for the below conditions, more research is needed. Please discuss your use of black seed oil with your registered dietitian nutritionist, pharmacist, or healthcare practitioner before using it for any of the following:

• Allergies
• Headaches
• High blood pressure
• Digestive disorders
• Boosting the immune system
• Reducing inflammation
• Fighting infections
• Acne
• Dry hair
• Psoriasis
• Hair growth
• Dry skin

What are the Side Effects of Black Seed Oil?

Consuming a supplement like black seed oil may have potential side effects. These side effects may be common or severe.

Common Side Effects

Very little is known about the long-term safety of black seed oil or how safe it is in amounts higher than what's typically found in food. However, some studies have found risks associated with black seed oil, including:

• Toxicity: A component of black seed oil known as melanthin (poisonous component) may be toxic in larger amounts.
• Allergic reaction: Applying black seed oil directly to the skin may cause an allergic skin rash known as allergic contact dermatitis in some individuals. In a case report, one person developed fluid-filled skin blisters after applying Nigella sativa oil to the skin. However, they also ingested the oil, so it's possible that the blisters were part of a systemic reaction (such as toxic epidermal necrolysis).
• Bleeding risk: Black seed oil may slow blood clotting and increase the risk of bleeding. Therefore, you should not take black seed oil if you have a bleeding disorder or take medication that affects blood clotting. In addition, stop taking black seed oil at least two weeks before a scheduled surgery.

For these reasons, be sure to talk with your healthcare provider if you're considering taking black seed oil. In addition, remember that black seed oil is not a replacement for conventional medical care, so avoid stopping any of your medications without speaking with your healthcare provider.

Precautions

People who are pregnant or lactating and children should not take black seed oil remedies due to the lack of research into their long-term safety.

Dosage: How Much Black Seed Oil Should I Take?

Always speak with a healthcare provider before taking a supplement to ensure that the supplement and dosage is appropriate for your individual needs.

Adults most often use black seed oil in doses of 1 to 2.5 grams by mouth daily for four to 12 weeks. Black seed powder has most often been used in doses of 1 to 2 grams by mouth daily for eight to 12 weeks. Speak with a healthcare provider to determine what dose might be best for a specific condition.

What Happens if I Take Too Much Black Seed Oil?

As a rule of thumb, never take more than the manufacturer's recommended dosage. If you experience side effects of any sort, stop taking black seed oil and call your healthcare provider.

Interactions

It is essential to carefully read the ingredient list and nutrition facts panel of a supplement to know which ingredients and how much of each ingredient is included. Please review this supplement label with your healthcare provider to discuss any potential interactions with foods, other supplements, and medications.

Drugs Interactions

It's also possible that black seed oil may interact with many common drugs, including:

• Drugs that treat high blood pressure, such as Norvasc (amlodipine)
• Immunosuppressants
• Diabetes drugs
• Serotonergic drugs (drugs that increase serotonin levels in the brain)
• Anticoagulant drugs (drugs that slow blood clotting)
• Sedative drugs
• Diuretic drugs (also known as water pills)

Herb and Supplement Interactions

It's also possible that black seed oil may interact with many common herb and supplement interactions, including:

• Herbs and supplements that might lower blood pressure (e.g., casein peptides, L-arginine, niacin, and stinging nettle)
• Herbs and supplements that might lower blood sugar (e.g., aloe, bitter melon, cassia cinnamon, chromium, prickly pear cactus)
• Herbs and supplements that might slow blood clotting (e.g., garlic, ginger, ginkgo, nattokinase, and Panax ginseng)
• Herbs and supplements with sedative properties (e.g., hops, kava, L-tryptophan, melatonin, and valerian)
• Herbs and supplements with serotonergic (affecting serotonin in the brain) properties (e.g., 5-HTP, L-tryptophan, SAMe, and St. John's wort).
• Iron: Black seed oil might increase the amount of iron the body absorbs.

How to Store Black Seed Oil

Store black seed oil according to the manufacturer's directions. Discard as indicated on the packaging.

Sources of Black Seed Oil & What to Look For

See below for more information on food and supplement sources of black seed oil.

Food Sources of Black Seed Oil

Black seed oil has been used in many countries as a spice and food preservative. It can be purchased in stores as an oil or powder.

Black Seed Oil Supplements

Black seed is often sold as a powder, tea, supplement, or oil. When buying a supplement, don't be fooled by claims that it can cure or treat any specific disease. Under the FDA labeling laws, it is illegal for manufacturers to make such claims, which are rarely supported by clinical evidence.

Summary

Some people use black seed oil supplements to treat certain health conditions, including arthritis, allergies, asthma, diabetes, and to maintain a healthy weight. While some studies support health claims, most are small, and more research is needed.

As a supplement, the FDA does not regulate black seed oil. You should use caution and work with your healthcare provider to determine if it is right for you and at what dosage.