MORPHINE: SIDE EFFECTS-SEDATION
There is considerable variation in these effects between individual patients. The common side effects in practice are constipation, sedation and nausea.
Sedation-Some sedation usually accompanies the commencement of morphine therapy. It is usually mild and lasts 2 to 5 days. Patients must be warned of the possibility of drowsiness, reassured that it is likely to improve within a few days and encouraged to persevere with their medication through this period. In a few cases, severe drowsiness and confusion may occur, necessitating dose reduction.
Sedation occurs more frequently in patients who:

• are elderly or frail
• have renal impairment
• have other causes of CNS depression, including CNS depressant drugs
• are opioid naive
• have only mild pain, or
• have had their pain acutely relieved by a procedure such as a nerve block

Persistent sedation requires assessment of renal function and exclusion of other causes of CNS depression including metabolic disturbances, infection, cerebral metastases and other drugs which may cause sedation.
Persistent sedation usually requires reduction of the dose of morphine unless there is a readily correctable metabolic cause or other less necessary medication can be withheld. If dose reduction leads to severe pain, an alternative opioid should be used. In elderly patients it is sometimes possible to slowly increase the dose, by small increments each 2 or 3 days, without recurrence of troublesome sedation. In exceptional cases, stimulants such as amphetamine or methylphenidate may be used. They are effective in counteracting sedation but there is a significant risk of dysphoric reactions to the stimulant, particularly in patients who are elderly or frail.
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Pain Relief/Muscle Relaxers