Heroin causes breathing, blood pressure and pulse to become slower and your mouth dries out. Higher quantities of heroin cause the immediate effects to intensify and last longer. Using a large quantity of heroin can cause death. Breathing becomes very slow, body temperature drops and heartbeat becomes irregular. .
The major problem of short-term use of any opiate is the way it is used. Under medical supervision, short-term use of opiates should not produce problems. Illicit drugs like heroin often lead to complicated health problems. Some of the problems are more likely to occur if the drug is injected, for example, heart and lung infections and diseases like hepatitis and HIV. In its pure form, heroin is relatively non-toxic to the body, causing little damage to body tissue and other organs. However, it is highly addictive and regular uses are very likely to become dependent on it after a few days. Some long-term effects include constipation, menstrual irregularity and infertility in women, and loss of sex drive in men. Street heroin is considered impure heroin, which is usually a mixture of pure heroin and other substances, such as caffeine and sugar. Additives can be very poisonous. They can cause collapsed veins tetanus, damage to the heart, lungs, liver and brain. Because the users don't know the purity and as a consequence the amount to take, it is easy to accidentally overdose and even die.
People who are physically dependent on heroin usually develop tolerance to the drug.
Dependence on heroin can be psychological, physical, or both. People who are psychologically dependent on heroin find that using it becomes far more important than other activities in their lives.
Physical dependence occurs when a person's body adapts to heroin and the body gets used to functioning with the drug present. Maintaining the habit can sometimes lead to users turning to crime to get enough money to pay for it.