Apraclonidine has tachyphylaxis; which side effect is commonly reported?

• A. Dry mouth
• B. Headache
• C. Increased tearing
• D. Conjunctival hyperemia

Answer: (A)

Tachyphylaxis means the drug’s effect on lowering IOP tends to diminish with continued use due to receptor desensitization. For apraclonidine, the issue about side effects focuses on what is commonly reported systemically after ocular application. A portion of the medication can be absorbed into the bloodstream, and this systemic exposure often leads to xerostomia (dry mouth) by reducing saliva production. While watering of the eyes (increased tearing) or conjunctival redness can occur, they are more typical ocular surface effects, not the systemic side effect emphasized here. Headache can happen but is less consistently reported than dry mouth. Therefore, dry mouth is the commonly reported systemic side effect.