Years ago, man discovered a variety of pain relievers that could be manufactured from chemicals or natural biological products such as certain plants. The bark of the willow produces aspirin and the poppy produces opium and a variety of opiate-related chemicals. The molecules of heroin are almost exactly like the opiate produced naturally by the body when in pain and heroin matched the opiate neuro-receptor almost exactly. Heroin is extremely addictive since it has such pleasurable effects on the brain and body and since it causes severe withdrawal symptoms when it is detoxified from the body leading to continued use to prevent the withdrawal.
Chronic use leads to addiction and dependency.
Many patients with chronic pain are treated with opiate pain relievers such as codeine, Vicodin, and many others. Continuous use can also lead to addiction and dependency. People addicted to heroin or pain-relievers have great difficulty getting off of the substance they are using because of the painful withdrawal systems. Though not fatal, the symptoms are extremely uncomfortable and include sweating, cramps, body pain, nausea, diarrhea, fever. Methadone, like all opiate pain relievers and heroin, is related to the natural opiate substances that the body produces and to the products of the poppy.