Overfølsomhedsreaktioner over for hydrochlorthiazid kan forekomme hos patienter med eller uden allergi eller bronkial astma i anamnesen, men er mere sandsynlige hos patienter med en sådan anamnese.
Hypersensitivity reactions to hydrochlorothiazide may occur in patients with or without a history of allergy or bronchial asthma, but are more likely in patients with such a history.