'allergenic' originates from the Greek word 'allergia,' where 'allos' meant 'other' and 'ergon' meant 'work.'

'allergia' transformed into the French word 'allergie,' and eventually became the modern English word 'allergy,' from which 'allergenic' is derived.

Initially, it meant 'a reaction to something foreign,' and this meaning has largely remained the same in modern usage.