SevereSide Effects of Emispan are Dryness in mouth, Blurred vision, Dizziness, Drowsiness, Nausea, Sedation, Tremors, Seizure, High blood pressure, Hypotension (low blood pressure), Asthma, Nasal congestion (stuffy nose), Respiratory depression, Apnea (absence of breathing), Injection site reactions (pain, swelling, redness), Tissue necrosis, Gangrene (dead tissue caused by an infection or lack of blood flow).