Respiratory and CNS depression may result in respiratory arrest. Depressant effects may be prolonged in patients with liver disease and chronic renal failure. Risk factors or comorbidities increasing risk for morphine-induced respiratory depression include naïve user lacking tolerance, hypothyroidism, morbid obesity, and sleep apnea syndrome. Note: Tidal volume may be depressed without perceptible changes in respiratory rate and these effects are influenced by external stimuli (eg, noise, manipulation).
Hypotension may occur owing to decreased systemic vascular resistance and venous tone.
Nausea, vomiting, and constipation may occur.
Bradycardia, wheezing, flushing, pruritus, urticaria, and other histamine-like effects may occur.
Sulfite preservative in some parenteral preparations may cause hypersensitivity reactions.
Use in pregnancy. FDA Category C (indeterminate). This does not preclude its acute, short-term use in a seriously symptomatic patient (See Introduction in Section III).