Thymoquinone as a causative allergen in Nigella sativa oil contact dermatitis with cross‐reactivity to tert‐butylhydroquinone

Severe allergic contact connubial dermatitis to Nigella Sativa Seed Oil due to repeated contacts to beard cosmetics

“…Thymoquinone (TQ) is the main constituent and the main allergen of NSO. TQ is not routinely tested but t‐butylhydroquinone, a structurally related synthetic reduced compound, could be a marker of TQ allergy and it can cross react with wood extracts 3,5 . The relevance of benzoyl peroxide remained unknown.…”

Tert‐butylhydroquinone is a marker for sensitivity to Nigella sativa oil allergy: Five new cases

“…TBHQ is not contained in NSO 11 but its chemical structure is similar to that of TQ. 8,12 TBHQ could be a pro-hapten.…”

“…Only NSO patch tests can be performed. In one recent case report 8 we reported that due to a close chemical structure between tert-butylhydroquinone (TBHQ) and TQ, positive patch tests with TBHQ, TQ, and NSO could be observed, suggesting that TBHQ could be a marker for sensitivity to TQ and so to NSO. To confirm this hypothesis, we report the results obtained in five consecutive patients with ACD to NSO also having been tested with TBHQ.…”

Black Seeds

“…183 As mentioned previously, the adverse effects of NS reported in human studies, such as nausea, anorexia, and dyspepsia, seem to be mild. Case reports of acute contact dermatitis [184][185][186][187][188][189][190] and systematic reactions [191][192][193][194] to NS have been documented. As a principal constituent of NS seed, TQ was evaluated in various toxicological studies.…”