Even though heroin and cannabis have been shown to induce euphoria, controlled studies comparing heroin and cannabis with amphetamines and cocaine have shown that amphetamines and cocaine produce euphoria more reliably and that euphoria is far more intense. Cocaine and amphetamines are two of the most common known stimulants that produce euphoria because they work in very similar ways. Cocaine is a naturally occurring chemical found in very significant quantities in the leaves of two different species of the coca shrub. It produces positive feelings in most users. Heroin works by stimulating the output of large amounts of dopamine but cocaine works mainly by blocking the re-uptake of dopamine. Amphetamines, on the other hand block the re-uptake
