[Strong opioids].

Oral route morphine should be first choice for moderate or strong cancer pain. Morphine must be administered essentially at fixed interval. It is important to keep effective plasma morphine concentration. When a patient can not take morphine via oral route, morphine must be administered by intravenous or subcutaneous infusion. Respiratory rate per minute of patients always must be measured during administration of morphine. Patients taking morphine have to take laxatives and antiemetics simultaneously. It is crucial to establish the cause of pain and choose other proper treatment when morphine is not effective.