"substance causing allergy," 1912, from allergy on model of antigen.
Entries linking to allergen
allergy n.
"condition caused by hypersensitivity of the immune system to typically harmless substances," 1911, from German Allergie, coined 1906 by Austrian pediatrician Clemens E. von Pirquet (1874-1929) as an abstract noun from Greek allos "other, different, strange" (from PIE root *al- (1) "beyond") + ergon "work, activity" (from PIE root *werg- "to do").
antigen n.
"substance that causes production of an antibody," 1908, from German Antigen, from French antigène (1899), from anti(body) (see antibody) + -gen.
hypo-allergenic adj.
also hypoallergenic, 1950; see hypo- + allergen + -ic.