When the patient's death is imminent because of the progression of primary disease, an increased risk of earlier death counts little against the benefit of pain relief and painless death. The ethical duty to benefit the patient through relieving pain is by itself adequate to support increasing doses to alleviate pain, even if there might be life-shortening and expected side effects. Because many patients in the terminal phase have been receiving opioid pain medications for a significant period of time, the fear of shortening life by medication is usually unfounded.
Prolonged use is known to affect sexual function and libido in both men and women.
Women experience amenorrhea and infertility, whereas men report an inability to attain or maintain an erection. Diphenhydramine, an antihistamine, may reduce pruritus in some patients.