Sooner or later, substituting one drug for another leads us back to our original drug of choice. Most often this happens because, under the influence of the substitute drug, we are no longer in control of our thoughts and actions, and 'drunk or high' we take our original drug of choice again.
The underlying reason for this is that as addicts, our body chemistry is addictive and so is hyper-sensitive to all addictive substances. Basically, our brain reacts in similar ways to all toxic mind-altering substances, even if the effects of the substance are different. So our brain stays in addictive mode, even if we don't take our original drug. Those neural associations and pathways have no opportunity to become disabled and dormant, and instead stay active and alert for the chance to latch back onto the original drug.
For this reason, many addicts and alcoholics have to be careful even when taking prescription drugs or over-the-counter medicines. Some alcoholics have reported unpleasant side-effects and cravings after taking cough mixtures, for example, which often contain small amounts of alcohol. Others have reported sudden urges and cravings following surgery and medication.
