May cause CNS depression. Might cause hypotension (use with caution in hypovolemia, cardiovascular disease (including acute myocardial infarction), or drugs which may exaggerate hypotensive effects). Use with caution in hypersensitivity reactions to other phenanthrene derivative opioid agonists (codeine, hydrocodone, hydromorphone, oxycodone, oxymorphone). May obscure diagnosis or clinical course of acute abdominal conditions. Use with caution in adrenal insufficiency, including Addison’s disease. Use with caution in biliary tract dysfunction (acute pancreatitis may cause constriction of sphincter of Oddi). Use with caution in CNS depression or coma. Tolerance, psychological and physical dependence might occur with prolonged use (use with caution in history of drug abuse or acute alcoholism). Use with extreme caution in head injury, intracranial lesions, or elevated intracranial pressure. Use with caution in severe liver dysfunction, in obesity, in prostatic hyperplasia and/or urinary stricture, and in severe renal insufficiency. Risk of critical respiratory depression (use with caution in pre-existing respiratory compromise (hypoxia and/or hypercapnia), chronic obstructive pulmonary disease or other obstructive pulmonary disease, and kyphoscoliosis or other skeletal disorder which may alter respiratory function). Use with caution in thyroid dysfunction. Effects may be potentiated when used with other sedative drugs or ethanol. Use with caution in debilitated patients (greater potential for critical respiratory depression), or in the elderly. Some preparations contain sulfites which may cause allergic reactions. The optimal analgesic dose varies widely among patients. Concurrent use of agonist/antagonist analgesics may precipitate withdrawal symptoms and/or reduced analgesic efficacy in patients following prolonged therapy with μ-opioid agonists. Abrupt discontinuation following prolonged use may also lead to withdrawal symptoms.