Heroin is made from the resin found in poppy plants.  A sap-like opium is removed from the pod of a poppy plant, which is refined to make morphine and following further refinement, heroin is made.  Heroin is highly addictive and most individuals who use heroin, inject the substance intravenously.  Heroin is a difficult substance to withdraw from which is why many individuals choose to keep using the drug then suffer the effects of withdrawal.

Heroin is a central nervous system depressant and binds to opiate receptors in the brain.  This binding causes the short-term effects of the drug.  Heroin can be injected, smoked, or snorted, which makes it more addictive.  Once the drug reaches the brain, it is converted to morphine by the body’s enzymes.  The morphine then binds to the opiate receptors in the cerebral cortex, thalamus, nucleus accumbens, brainstem, and spinal cord.

These areas of the brain include pain pathways and reward pathways.  The areas associated with the reward pathway release dopamine, which makes someone feel euphoric.  The pain pathways get numb from the binding of morphine, which causes the inability to feel pain.  These areas are what make heroin appealing—numbing pain and helping someone to feel euphoric.  Individuals experience pleasure and is why many use the drug again and again.

The short-term effects of heroin include euphoria, lack of pain, drowsiness, and mental functioning that is clouded by the drug.  These short-term feelings create such a pleasurable experience that many who use the drug do not care about the negative side effects.  The effects of a single heroin use can last for several hours and once the drug begins to wear off, the individual might experience nodding off.  This is a period of time in which one can be in a wakeful and drowsy state at the same time.  Without the drug, people will start to feel nauseous, itchiness, and have respiratory depression.  Therefore, many people continue to use the drug, as withdrawal can be very uncomfortable.

The long-term effects of using heroin on the brain can lead to addiction.  Many individuals report that they continue to use the drug because they are seeking the same high as when they first used.  The brain is affected mostly through psychological experiences such as tolerance, cravings, and dependence.  Tolerance occurs because the individual wishes to remain “high” but over time needs more and more of the drug to accomplish this.  Cravings occur due to the increased activity of glutamate, a cortical excitatory neurotransmitter.  Dependence can be physical and psychological where individuals need to have the drug to feel normal.