Speeballing is a term commonly referring to the intravenous use of heroin, morphine, or oxycontin and cocaine (or one of the amphetamines) together in the same needle. This is a potentially lethal concoction: the cocaine acts as a stimulant, raising the pulse, but its effects wear off more quickly than those of either heroin or morphine, which in turn slow the heart down. As a result, it is possible to experience a delayed "overdose" (technically, severe respiratory depression) when the stimulant wears off and the full effects of the heroin are felt in isolation.