Patients w/ HTN, convulsive diseases or CVA; suffering from or w/ history of resp, CV, liver, kidneys/urinary, digestive (eg, ulcer) impairment; intracranial pressure; addicted to opioids. Prolonged & high dose may produce tolerance, physical & mental dependence. Cough persisting for >2-3 wk. May affect the ability to drive or operate machinery. Pregnancy. Elderly.