Morphine is a narcotic that affects the central nervous system. Besides relieving pain, morphine impairs mental and physical performance, relieves fear and anxiety, and induces euphoria. Morphine's euphoric effects can be highly addictive. Tolerance (the need for higher and higher doses to achieve the same effect) and physical and psychological dependence quickly develop.
Withdrawal from morphine addiction causes nausea, chills and sweats, lasting up to three days.