Traditionally, the purity of heroin in a bag has ranged from one to ten percent. The color and consistency of black tar heroin result from the crude processing methods used to illicitly manufacture heroin in Mexico. Black tar heroin may be sticky like roofing tar or hard like coal. It's color may vary from dark brown to black. Black tar heroin is most frequently dissolved, diluted, and injected.
Injection is the most practical and efficient way to administer low-purity heroin.
The availability of higher purity heroin has meant that users now can snort or smoke the narcotic. Evidence suggests that heroin snorting is widespread or increasing in those areas of the country where high-purity heroin is available, generally in the northeastern United States. As with other injectable narcotics, frequent injection will eventually cause the user's veins to collapse. When this happens, the user will have to find new veins to inject the heroin into. Psychological symptoms exhibited by a person who is using heroin are severe depression, irritability, and restlessness. .