Hypotension; fatigue, drowsiness, dizziness, nervousness, headache, restlessness, malaise, confusion, depression, hallucinations, tremors, muscle twitches, increased intracranial pressure, seizure, serotonin syndrome; rash, urticaria; nausea, vomiting, constipation, anorexia, stomach cramps, xerostomia, biliary spasm, paralytic ileus, sphincter of Oddi spasm; ureteral spasms, decreased urination; pain at inj site; weakness; dyspnoea; histamine release, physical and psychological dependence.