It slows the pulse and breathing rate, causes a drop in blood pressure, and relaxes the muscles. A person who is high on heroin may therefore exhibit poor coordination, have slowed reflexes, watery eyes and nose, dilated pupils and slurred speech.
Users also have a loss of appetite.
Injection itself poses risks. A user whose syringe is faulty or who out of carelessness injects some air into the vein may die in as little as a few seconds when a tiny bubble reaches the brain. There is also the possibility of contracting HIV disease by sharing infected needles. Heroin withdrawal can be severe, sometimes even fatal. Withdrawal symptoms range from severe cold-like symptoms to include anxiety, insomnia, tremors, delirium and convulsions.