Allergy to non-toxoid constituents of vaccines and implications for patch testing.

We report 3 patients with persistent symptoms at vaccination sites. All were allergic to aluminium and one to thiomersal and neomycin too. Aluminium allergy causes false positive patch test reactions and we propose methods of patch testing patients with symptoms at vaccination sites in order to avoid this problem. The practical relevance of allergy to non-toxoid constituents of vaccines is discussed.