Heroin is extremely addictive no matter how it is administered, although routes of administration that allow it to reach the brain the fastest (i.e., injection and smoking) increase the risk of addiction. Once a person becomes addicted to heroin, seeking and using the drug becomes their primary purpose in life (no interest in studies, work and to enjoy other things in life). People who use heroin can commit crimes or sell sex in search of money to buy the drug and can face legal issues for its use if they are not registered for medical treatment.