In its purest form, heroin is a fine white powder. But more often, it is found to be rose gray, brown or black in color. The coloring comes from additives which have been used to dilute it, which can include sugar, caffeine or other substances. Street heroin is sometimes “cut” with strychnine1 or other poisons. The various additives do not fully dissolve, and when they are injected into the body, can clog the blood vessels that lead to the lungs, kidneys or brain. This itself can lead to infection or destruction of vital organs.