It is formed from L-histidine through the action of histidine ammonialyase (also known as histidase or histidinase) by elimination of ammonium.

An important role for the onset of atopic dermatitis and asthma has been attributed to filaggrin, a skin precursor of urocanic acid.

[1][2] Urocanic acid is thought to be a significant attractant of the nematode parasite Strongyloides stercoralis,[3] in part because of relatively high levels in the plantar surfaces of the feet, the site through which this parasite often enters the body.

Urocanic acid was detected in animal sweat and skin where, among other possible functions, it acts as an endogenous sunscreen or photoprotectant against UVB-induced DNA damage.

Urocanic acid is found predominantly in the stratum corneum of the skin and it is likely that most of it is derived from filaggrin catabolism (a histidine-rich protein).