Different drugs affect the body in different ways. Many drugs, such as cocaine, are toxic to the body and cause tissue damage. Alternatively, drugs may harm the body through their route of ingestion, such as smoking of marijuana or injection of opiates. The lifestyle adopted by heavy drug users may also physically harm the user. For instance, heavy amphetamine users may experience malnutrition due to loss of appetite caused by the drug. A cocaine or amphetamine overdose can even cause a heart attack.