Black Seed Oil: Health Benefits and More

Black seed oil is a supplement extracted from the seeds of Nigella sativa, also known as black cumin. Nigella is a flowering plant native to parts of Europe, northern Africa, and Southwest Asia. Black seed oil has a long history dating back over 2,000 years.

Black seed oil contains the phytochemical thymoquinone, which has antioxidant properties. Antioxidants help rid the body of harmful particles called free radicals.

This article discusses the benefits and risks of black seed oil.

Black Seed Oil Benefits

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.

May Lower Blood Sugar

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 as oil, tea, or seeds. Results indicated that participants had a decrease in their fasting blood glucose. It is important to note that in most 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.

May Help 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

May Reduce Allergies and 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 (blocks histamines to relieve allergies)
• Immune-modulator (something that affects the immune system)
• Antimicrobial
• Analgesic (reduces pain without drowsiness)

May Assist Weight Management

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 did aerobic exercise.

Researchers found that the treatment combination of diet, exercise, and black seed oil provided benefits, including lowering weight and cholesterol levels. Still, the authors concluded that further studies with a larger sample size and diet assessment are needed.

May Support Acne Treatment

Black seed oil applied as a hydrogel directly to skin has shown significant effects in improving the symptoms of acne with no adverse reactions.

May Help Psoriasis

According to clinical studies, black seed essential oil and extract helped treat chronic inflammatory skin conditions, including psoriasis. However, more research is needed to validate the efficacy of black seed oil therapy for autoimmune skin issues.

May Help Treat Eczema

Black seed oil has anti-inflammatory, anti-oxidant, and anti-apoptotic (preventing cell death) properties. This makes it effective in treating inflammatory skin conditions that can lead to infections and cause skin cells to turn over too rapidly (resulting in scaly plaque formations), like eczema.

May Support Hair Health

While researchers have used nigella for hair combined with other herbs in animal studies, its effectiveness in humans is yet to be determined.

May Fight Inflammation

A 2016 comprehensive review of scientific reports concluded that Nigella sativa has many anti-inflammatory, anti-oxidant, and wound-healing effects, among other therapeutic properties. The results demonstrated black seed oil's potential to treat many inflammatory conditions. 

May Help Treat Hashimoto's Thyroiditis

Data supports the potent benefit of using powdered Nigella sativa to improve Hashimoto's thyroiditis. Nigella sativa had observable effects in relieving Hashimoto's symptoms, according to a 2016 randomized controlled trial, and can be regarded as a therapeutic approach to managing Hashimoto's thyroiditis. 

May Support Metabolic Syndrome

Metabolic syndrome (a group of five conditions that can lead to heart disease, diabetes, stroke, and other issues) responds well to treatment with black seed oil. A 2020 study of post-menopausal women concluded that Nigella sativa could be recommended to improve lipid profiles and blood sugar levels in those with metabolic syndrome.

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 provider before using it for any of the following:

• Headaches
• High blood pressure
• Digestive disorders

Dosage: How Much Black Seed Oil Should I Take?

Black seed oil doses typically range from 1 to 5 grams by mouth per day for four to 12 weeks. Black seed powder ranges from 1 to 2 grams by mouth daily for eight to 12 weeks.

Is Black Seed Oil Safe For Me?

Black seed oil may not be safe for everyone. For example, avoiding its use during pregnancy and lactation is suggested. 

Black Seed Oil Side Effects

Consuming a supplement like black seed oil may have potential side effects. Studies have found risks associated with black seed oil, including:

• Toxicity: A component of black seed oil known as melanthin 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. Avoid 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.

Drugs Interactions

Black seed oil may interact with common medicines, including the following:

• High blood pressure medications such as Norvasc (amlodipine)
• Immunosuppressants
• Diabetes medications
• Serotonergic medications (SSRIs, SNRIs, TCAs, MAOIs)
• Anticoagulants (which slow blood clotting)
• Sedatives
• Diuretics (aka water pills)

Herb and Supplement Interactions

It's also possible that black seed oil may interact with common over-the-counter (OTC) herbs and supplements, including:

• Blood pressure lowering: Casein peptides, L-arginine, niacin, and stinging nettle
• Blood sugar lowering: Aloe, bitter melon, cassia cinnamon, chromium, and prickly pear cactus
• Blood thinners: Garlic, ginger, ginkgo, nattokinase, and Panax ginseng
• OTC sedatives: Hops, kava, L-tryptophan, melatonin, and valerian
• OTC serotonergics: 5-HTP, L-tryptophan, SAMe, and St. John's wort
• Iron: Black seed oil might increase the amount of iron the body absorbs

Summary

Some people use black seed oil supplements to treat certain health conditions, including arthritis, allergies, asthma, and 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.