Unlike other drugs, intense psychological dependence is developed with even occasional low doses. Street purchases are commonly substitute or diluted drugs. The unsuspecting buyer risks having no knowledge of what he or she is taking or what the effects may be. Irregular breathing and heartbeat, respiratory and cardiac arrest. Slowed breathing may lead to oxygen starvation and brain damage.
Death results from overdose which brings on lung and heart complications.
The tolerance which develops causes progression to higher doses. Fear of withdrawal creates dependence in itself. Withdrawal and abstinence reduce tolerance for only a brief period. Psychological dependence can be prolonged after withdrawal with depression, anxiety, inability to sleep, lack of appetite, restlessness, and craving for the drug. Loss of sense of pain, psychic experiences, states of panic and fear of death lasting for several days.