Stimulant drugs such as cocaine, "crack," amphetamines, and caffeine are substances that speed up activity in the brain and spinal cord. This, in turn, can cause the heart to beat faster and blood pressure and metabolism to increase. Stimulants often influence a person to be more talkative and anxious and to experience feelings of exhilaration.
Use of cocaine and other stimulants can cause someone's heart to beat abnormally fast and at an unsteady rate. Use of these drugs also narrows blood vessels, reducing the flow of blood and oxygen to the heart, which results in "starving" the heart muscle. Even professional athletes whose bodies are well-conditioned have succumbed to cocaine's ability to cause heart failure. Researchers currently have no way to detect who may be more susceptible to these effects.