Question

Why is it that once a person starts taking alcohol or drugs, it is difficult to get rid of this habit?

Answer 1

Alcohol, often known by its chemical name ethanol, is a psychoactive substance that is found in alcoholic beverages such as beer, wine, and distilled spirits (hard liquor). It is one of the oldest and most widely used recreational drugs, producing the same intoxicating effects as alcohol ("drunkenness").

Complete answer:
Intoxication with alcohol or drugs impacts brain cells directly, altering the equilibrium of neurotransmitter secretion. While brain cells are exposed to alcohol or drugs for an extended period of time, they adapt to these alterations, and the production of specific neurotransmitters is changed to function normally when the substance is present in the blood. These long-term chemical changes render a person hooked to drugs or alcohol and cause withdrawal symptoms when they try to quit.
Drug and alcohol use has a built-in addictive quality linked with pleasure and a fleeting sense of well-being. The tolerance level of the body's receptors rises with repeated drug administration, leading to increased drug consumption. When a person begins to use alcohol or drugs, he gets physically and mentally addicted to them. He exhibits unpleasant withdrawal symptoms such as vomiting, diarrhoea, shivering, twitching, sweating, stomach and muscular cramps, and so on whenever he attempts to get rid of his habit.
As a result, it is tough for a person to break this behaviour.

Note:
Although ethanol is only one of numerous kinds of alcohol, it is the only one found in alcoholic drinks or frequently used for recreational reasons; other alcohols, such as methanol and isopropyl alcohol, are far more hazardous. Isopropanol is only somewhat more poisonous than ethanol, so a low, transient dose is unlikely to cause severe injury. Methanol, which is even more poisonous than ethanol, may kill you in as little as 10–15 millilitres.