Is the topical use of black seed oil dangerous?

Theblack seed oil is typically obtained through cold pressing from black cumin seeds. It presents itself as an amber-coloured oil with a slight spicy fragrance. The black seed oil is included in the composition of several cosmetic treatments due to its numerous benefits derived from the active ingredients it contains. It is particularly rich in fatty acids, compounds that provide it with moisturising and nourishing properties, useful for dehydrated or dry skin, but also for preventing dehydration fine lines.

Black seed oil also possesses anti-inflammatory and antioxidant properties, conferred by its active ingredient: thymoquinone. This botanical extract can thus be used to alleviate certain redness or itching and prevent the appearance of wrinkles. Finally, a study on rats has shown that black seed oil was capable of accelerating the skin healing process, suggesting that this ingredient can reduce the appearance of purple stretch marks.

When applied topically, it is important to know that black seed oil should always be diluted in another vegetable oil, such as jojoba oil, sweet almond oil or argan oil for instance. Some people are indeed quite sensitive to this vegetable oil and its pure topical application can sometimes lead to redness, tingling or itching. Scientists have not determined which molecule present in black seed oil is responsible for these reactions, but thymoquinone is a potential candidate.

Furthermore, a study recently reported that between 2010 and 2016, the topical application of black seed oil resulted in six individuals experiencing cases of epidermal necrolysis which required hospitalisation. This severe hypersensitivity reaction is characterised by the detachment of epithelial and mucous tissues. After treatment with corticosteroids, the individuals who reacted were able to find relief. This dramatic reaction is fortunately extremely rare and was observed after the application of pure black seed oil, hence the importance of using this ingredient in a diluted form.

Black seed oil can be applied to the skin, scalp or hair. However, it is not suitable for mucous membranes or the eye contour. Therefore, if you are using black seed oil on your face, it is important to avoid any contact with the eyes. As mentioned earlier, it is important to dilify the black seed oil before applying it. A dilution of 5 to 10%, depending on your skin's sensitivity, is generally recommended.

To reap the benefits of black seed oil, it is also recommended to obtain a organic oil cold-pressed. Indeed, this process does not require any chemical treatment or heating the oil to a high temperature, which could destroy certain fatty acids in the vegetable oil and lead to the formation of new compounds, not necessarily beneficial for the skin.

Finally, before incorporating black seed oil into your skincare routine, it is advisable to conduct a tolerance test, to ensure that your skin does not react to this ingredient. To do this, apply a small amount of black seed oil to the inside of your elbow or behind your ear and wait 24 hours. If you observe no redness, irritation or itching, you can use it.

• ORO S. & al. Dermites de contact à l’huile de nigelle : une nécrolyse épidermique toxique « de contact » ? Annales de Dermatologie et de Vénéréologie (2017).

• KIM B. & al. Black cumin ( Nigella sativa L.): A comprehensive review on phytochemistry, health benefits, molecular pharmacology, and safety. Nutrients (2021).