Abuse

How does taking heroin trigger the “hit,”or high, and other resulting effects? Once it enters the body, heroin is converted back into morphine. Upon reaching the brain, opiates affect the central nervous system, impacting both physical and psychological functioning.

Although heroin and morphine work the same way in the brain, heroin acts more quickly because of chemical modifications. When injected directly into a vein, it reaches the brain within ten seconds. Users may instead choose to inject into a muscle, called skin popping, rather than directly into the bloodstream. (This method is easier and less dangerous.) The effect produced by injecting into a muscle is more gradual, taking about five minutes to be felt.

Heroin can also be smoked, often through a method called “chasing the dragon,” in which the drug is placed on a piece of tin foil and heated from beneath. Users inhale the resulting vapor with a tube, and the effect is nearly as fast as with intravenous injection. The effect from snorting powdered heroin takes about ten to fifteen minutes to kick in.

The surge of euphoria, dulling of pain, and other sensations associated with heroin use is caused by the activity of certain nerve cells in the brain. Opiates work by binding to certain receptor molecules on nerve cells, receptors linked with stimulating pleasure and coping with pain. These receptors can also be activated by naturally occurring chemicals in the brain called endorphins and enkephalins, but activation occurs only to a limited extent. Opiates bombard the receptors. The resultant “rush” far exceeds any naturally occurring effect, activating what is known informally as one of the pleasure circuits in the brain.

Since opiates affect brain function, and the central nervous system controls all of the other systems of the body, heroin use causes a variety of physical side effects. It slows down breathing and motor skills, and it causes slurred speech. Users often go “on the nod” soon after taking a dose of the drug, slumping into a stupor and letting their eyelids droop. Some people find this a frightening experience, like a suffocating faint. If the state is broken, such as by a touch on the shoulder or an unexpected sound, it can provoke a startled or aggressive reaction.

The brain registers heroin as a toxin, triggering nausea, especially for first-time users, and sometimes vomiting. The pupils of the eyes contract, sometimes to pinpoints. Heroin can cause users to become flushed and sweaty. Opiates can trigger a release of histamine, which makes users' skin feel itchy. They also interfere with the digestive tract, causing constipation and other digestive problems.

The effects of heroin last between four and six hours. For someone who is not addicted, the dreamlike state slowly wears off. The user may have a hangover but not the symptoms of withdrawal. For addicts, however, “coming down” is much more difficult. Heroin changes the body chemistry of addicts, and as soon as the effects of one dose fade, addicts crave more.

Since heroin slows breathing, an overdose of the drug can quickly lead to respiratory failure, coma, and death. Symptoms of an overdose may include clammy skin, blue fingers and lips, and convulsions. Generally, an overdose can be reversed by an injection of the antidote drug naloxone if detected in time. It causes the opiates to be ejected from the receptor sites in the brain.