Not Medical Advice: Fixed and dilated pupils are observed when taking diphenhydramine like Benadryl®.
Benadryl is an antihistamine. Diphenhydramine blocks the effects of the naturally occurring chemical histamine in the body.
Benadryl is used to treat sneezing; runny nose; itching, watery eyes; hives; rashes; itching; and other symptoms of allergies and the common cold.
Benadryl is also used to suppress coughs, to treat motion sickness, to induce sleep, and to treat mild forms of Parkinson's disease.
More common side effects of Benadryl include:
Sedation
sleepiness
dizziness
disturbed coordination
epigastric distress
thickening of bronchial secretions
See a comprehensive list of adverse effects at Drugs.com.
Tip! Severe Allergies: Managing Allergens to Control Seasonal Allergies shared by WebMD.