Morphine is a narcotic that's extracted from the opium poppy. It's used in medicine as a pain reliever, but is popular as a street drug because of its euphoric effects. Morphine can cause a number of unwanted side effects, including drowsiness, mental confusion, respiratory problems, and depression of the central nervous system. Morphine desensitizes the respiratory center in the brain that regulates breathing. This can be extremely dangerous because it slows down brain signals to the lungs. Although the decreased breathing caused by a moderate dose may not cause an immediate problem, when morphine is taken in conjunction with another central nervous system depressant, such as alcohol, sedatives, or tranquilizers, it can be fatal. Needle sharing is another danger to morphine addicts. Needle sharing increases the risk of acquiring infectious diseases such as hepatitis and HIV (H-I-V), and it's believed that morphine abuse may lower the resistance of the immune system, thereby making addicts more vulnerable to the AIDS virus. For more information about morphine, consult a health care professional in your area.