overdoses can lead to coma and even death due to inhaling vomit as heroin sedates you and stops you coughing properly as it can cause respiratory failure, if heroin is taken with other drugs overdose is more likely, injecting heroin can damage veins and arteries which is known to lead to gangrene, sharing needles, syringes and equipment puts you and other people in danger of serious infections, addiction is a disastrous effect on family relationships and ability to hold down a job