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

## TL;DR

A patient presented with a dilated pupil caused by azelastine, highlighting the importance of a detailed medical history in avoiding unnecessary tests.

## Contribution

This case emphasizes the role of thorough anamnesis in diagnosing azelastine-induced anisocoria.

## Key findings

- Unilateral mydriasis was identified as a rare side effect of azelastine.
- A detailed patient history helped avoid unnecessary diagnostic procedures.
- The case underscores the importance of considering medication history in anisocoria evaluation.

## Abstract

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.