Pharmacologic Anisocoria With Azelastine: The Importance of a Good Anamnesis.

Unilateral pharmacologic mydriasis is one of the differential diagnoses of anisocoria. This is a clinical case of a 37-year-old male patient admitted to the ophthalmology emergency department with unilateral mydriasis, an infrequent side effect of the antihistaminic drug azelastine. A comprehensive medical history including ocular medication was essential to avoid the need for additional tests and to exclude life-threatening conditions responsible for a similar presentation.