Molecular model of the drug morphine. Morphine is a narcotic drug derived from the opium poppy. It is used to treat severe pain due to its potent analgesic (painkilling) properties. It acts on receptors that are naturally triggered by endorphins, the body's natural painkillers. Morphine is also abused as it produces feelings of euphoria and dreaminess. Morphine is highly addictive and the body also develops tolerance quickly, so that larger doses are needed to achieve the same effect. Atoms are represented as spheres and are colour-coded: carbon (black), hydrogen (white), nitrogen (blue) and oxygen (red).