Black Seed Oil: Potential Benefits, Known Risks, and More
Note: The U.S. Food and Drug Administration (FDA) does not approve supplements for safety or effectiveness. Talk to a healthcare professional about whether a supplement is the right fit for your individual health, and about any potential drug interactions or safety concerns.
Black seed oil is a dietary supplement extracted from seeds of the Nigella sativa plant. The oil in these dark-colored seeds (sometimes called black cumin or black caraway seeds) has been used for centuries as a traditional remedy for a variety of health conditions, including acne, asthma, arthritis, seasonal allergies, and diabetes.
While generally safe, black seed oil can cause side effects, including rash (if applied topically), allergic reactions, irregular periods, and gastrointestinal (GI) discomfort and nausea. People who take blood thinners, are pregnant, or have an upcoming surgery should steer clear of black seed oil.
Black seed oil contains high levels of antioxidants and other compounds believed to offer health benefits, says Casey Kelley, MD, a board-certified family medicine physician in Chicago specializing in functional medicine.
Black seed oil is particularly high in thymoquinone, an antioxidant that may reduce inflammation and oxidative stress (an imbalance between antioxidants and free radicals, a type of molecule that causes damage to other molecules), Dr. Kelley says.
Research on black seed oil isn’t considered robust enough to prevent or treat any health condition. But some studies have examined some of the potential health effects of this oil and seen positive results. Black seed oil may be useful to do the following:
Reduce Acne
A randomized, double-blind clinical trial found that topically applying black seed oil reduced acne — specifically acne lesions called comedones (blackheads), papules (tiny, red, hard pimples), and pustules (whiteheads). The study involved 60 patients, half of whom received gel made from black seed oil twice daily for 60 days. The other half applied a placebo gel. The researchers found the treatment gel led to significant reductions in comedones, papules, and pustules compared with the placebo after two months. The researchers theorized this is likely due to black seed oil’s antibacterial and anti-inflammatory properties.
Still, further research is needed to determine whether topical black seed oil is an effective acne treatment, says Karen E. Todd, RD, founder of The Supplement Dietitian based in Dripping Springs, Texas.
May Have Protective Properties Against Cancer
A lab study using mouse cancer cells found that when seeds were roasted to 50 to 150 degrees Celsius (122 to 302 degrees F), the extracted oil had an anticancer effect and higher thymoquinone levels (which may play a role in anticancer activity).
Similarly, a review of laboratory studies found that thymoquinone from black seed oil may inhibit cancer cell activity in various ways, and may hold promise as a cancer therapy in the future. Like with other purported benefits, more human research is needed to confirm this one, Todd says.
Alleviate Asthma Symptoms
Thanks to its anti-inflammatory properties, black seed oil may help tame symptoms of asthma. One study found taking 500 milligrams (mg) of black seed oil capsules twice a day for four weeks led to significant improvements in Asthma Control Test scores compared with a placebo. (The Asthma Control Test is a self-administered test that assesses how often a patient experiences shortness of breath, uses rescue medications, and how asthma affects daily life.)
Researchers behind a review on the effects of black seed oil on asthma noted, though, that the evidence is weak and more research is needed. Given the seriousness of untreated asthma, it’s smart to stick with conventional treatments such as inhaled corticosteroids or montelukast as first-line treatment.
Improve Hair Health
Black seed oil taken as a supplement or used as an ingredient in soap, shampoo, hair masks, creams, and other hair products may boost hair volume, shine, and texture and support healthy hair. This is theorized to potentially be due to black seed oil containing fatty acids, which help promote blood circulation (and thereby hair growth).
Todd says that while this benefit has been shown, more research is needed to confirm. The studies that have been done were either small (20 or fewer participants) or involved a blend of oils versus just black seed oil, Todd says.
Lessen Seasonal Allergy Symptoms
About 92 percent of people with allergic rhinitis (also known as hay fever, a common seasonal allergy that causes cold-like symptoms) who used nasal drops containing black seed oil daily for six weeks saw a reduction in symptoms compared with 30 percent in the control group that used a nonmedicinal food oil. However, this benefit isn’t well studied and rigorous clinical trials are needed to determine if it should be used as a treatment option.
Ease Rheumatoid Arthritis Pain
Black seed oil supplements may reduce pain and inflammation in people with rheumatoid arthritis (RA, a chronic inflammatory condition that affects the joints). This benefit was found in some studies involving both humans and animals and is believed to be due to the anti-inflammatory effect of thymoquinone. Still, the authors of one review concluded that more research is needed to determine if black seed oil is an effective therapy for people with RA.
Until then, it’s best to stick to conventional options to treat arthritis pain and inflammation.
Help Control Diabetes
Research suggests that black seed oil may help control diabetes by reducing fasting blood sugar (how much sugar is in your blood after not eating or drinking for at least eight hours). This effect may be due to an improvement in the function of insulin-producing pancreatic beta cells and insulin resistance (a condition where the body doesn’t respond to insulin the way it should) when black seed oil was used alongside oral diabetes medications. The researchers concluded that black seed oil may be a potential complementary approach to use alongside conventional diabetes treatments and lifestyle changes (such as dietary changes, exercise, and prescription medications), yet concluded that more studies are needed to determine the best type, dose, and use for anti-diabetic effects. Todd agrees that more human research is needed to confirm.
Preliminary research suggests that black seed oil supplements reduce appetite when taken consistently, leading to weight loss.
In one review of 19 studies (five done in animals), researchers concluded that black seed oil supplements taken daily for 6 to 12 weeks significantly reduced body weight in people and animals with obesity and type 2 diabetes.
The studies in which participants took 1 to 3 grams (g) of black seed oil daily saw more significant weight loss results than those that used black seed oil in powder form, even though the doses were equal. The researchers say this difference in effectiveness may be due to a higher concentration of beneficial fatty acids and antioxidants in oil versus powder. However, more quality studies are needed to better understand the mechanisms and weight loss effects of black seed oil. Still, Kelley cautions against relying on black seed oil as a magic pill for weight loss. “While black seed oil may aid in weight management, it should be combined with healthy eating and regular physical activity for the best results,” she explains. “It is not a cure-all solution on its own.”
Black seed oil isn’t without risks and side effects. Because the FDA regulates dietary supplements differently from conventional drugs, do your own research before taking any supplements to ensure purity and quality.
Risks
Black seed oil is generally safe for most people, Kelley says. However, she adds it can cause allergic reactions, digestive issues, and lower blood pressure or blood sugar levels in people taking blood pressure or diabetes medications.
“It may also slow blood clotting and interact with medications, such as beta-blockers, anticoagulants, and diabetes medications,” Kelley says. Pregnant and breastfeeding women and people with liver or kidney issues should be particularly cautious about using it, she adds.
Because black seed oil can slow blood clotting, it shouldn’t be taken if you have an upcoming surgery. It has also been reported that someone with diabetes experienced kidney failure after taking black seed oil.
To be safe, talk to your doctor before taking black seed oil.
Side Effects
Reported side effects of black seed oil supplements include:
Rashes and allergic reactions from ingestion and topical application
Irregular periods
Nausea and GI discomfort
Black seed oil supplements come in the following forms:
Capsules
Gummies
Powders
Oral liquids
Topical liquids
Topical gels
Topical creams
Because it’s an edible oil, black seed oil can also be used in cooking, though research suggests it should not be heated to temperatures above 50 to 150 degrees Celsius (120 to 300 degrees F), says Jenna Volpe, RDN, a functional dietitian and clinical herbalist in Austin, Texas. Heating black seed oil to very high temperatures could potentially reduce or negate the health benefits or even create a pro-inflammatory substance, Volpe explains.
Follow these best practices from experts for selecting and storing black seed oil.
Selection
When choosing a black seed oil supplement, check that a third-party agency has tested it for safety and purity. Third-party testing companies include NSF (National Sanitation Foundation), USP (U.S. Pharmacopeia), and ConsumerLab, which place their seal on products to indicate quality and purity.
Black seed oil gummies may include added sugar. If you’re watching your sugar intake, choose capsule or liquid supplements, Volpe advises.
Storage
Volpe advises storing black seed oil liquids, capsules, and gummies in a cool, dry place in a sealed container.
If you purchase liquid oil in a plastic bottle, transfer it to a dark-colored glass one. According to Volpe, darker-colored glass preserves black seed oils’ potency better than plastic or clear glass since it protects against the damaging effects of light.
According to the National Institute of Diabetes and Digestive and Kidney Diseases, the typical recommended dose of black seed oil is 300 to 1,000 mg taken one to two times daily. For reference, 1,000 mg is equal to less than ¼ teaspoon of ground black cumin seeds — comparable with the amount you might use in some recipes.
But the appropriate dose varies depending on factors unique to each person, says Volpe. These include weight, age, and underlying health conditions. Talk to your doctor about the appropriate dose for you.
The Takeaway
Black seed oil is a dietary supplement extracted from the seeds of the Nigella sativa plant.
It may help people with skin issues, obesity, diabetes, asthma, allergies, and rheumatoid arthritis, but more research is needed to confirm the benefits.
Because black seed oil can interact with medications, slow blood clotting, and cause other side effects, it’s important to talk to your doctor before introducing it as a complementary approach to your wellness routine.
