Does biotin (or its precursors) act as an allergen or hapten?

Although vitamin allergies are considered rare, biotin’s widespread use raises the question of whether it can directly trigger hypersensitivity.

Documented hypersensitivity to biotin itself is extremely rare; only two published occupational cases describe contact allergy to biotin or its synthetic precursors, and no cases have been reported from dietary, cosmetic, or therapeutic use of biotin.