The effects of any drug vary from person to person. It depends on many factors, including: - the person's size, weight and health - how the drug is taken - how much is taken - whether the person is used to taking the drug - the person's mood - whether other drugs are taken - the environment in which the drug is used, for example, whether the person is alone or with others, such as in a social setting. The effects of heroin or opium may last 3 to 4 hours. Immediate effects - Intense pleasure: Heroin may cause a rush of intense pleasure and a strong feeling of wellbeing. - Pain relief: Heroin relieves physical pain. After using heroin, feelings of pain, hunger or sexual urges are diminished. - Physical symptoms: Breathing, blood pressure and pulse become slower. The pupils of the eyes also get much smaller. The mouth dries out. - Drowsiness: As the amount used increases, the user may feel warm, heavy and sleepy. - Nausea and vomiting can occur. In greater quantities The immediate effects intensify and last longer with higher quantities of heroin. As the quantity used increases, the following effects are also likely to occur: - Concentration: The ability to concentrate is impaired. - Likelihood of sleep: The user is likely to fall asleep ('on the nod'). - Breathing: Breathing becomes shallower and slower. - Nausea: With higher quantities, nausea and vomiting are more likely to occur. - Bodily effects: Sweating, itching and increased urinary output is also likely. Short-term effects Apart from overdosing, the major problem with short-term use of any opiate is the way it is used. Under medical supervision, short-term use of opiates should not produce problems. Many people are given pethidine for two or three days after an operation and do not experience any health problems. However, illicit drugs like heroin often lead to complicated health problems. Some of these problems are more likely to occur if the drug is injected; for example, skin, heart and lung infections, and diseases like hepatitis and HIV. Long-term effects 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 users are very likely to become dependent on it, even after a few days. Some long-term effects include constipation, menstrual irregularity and infertility in women, and loss of sex drive in men. Users often spend less on other things like housing and food and, combined with reduced appetite, this can lead to malnutrition and susceptibility to infections. Street heroin is usually a mixture of pure heroin and other substances, such as caffeine and sugar. Additives can be highly poisonous. They can cause collapsed veins, tetanus, abscesses and damage to the heart, lungs, liver and brain. Because the users don't know the purity of the heroin used, and therefore the amount to take, it is easy to accidentally overdose.