Many people enjoy the psychological effects of various chemicals. Any chemical can have unwanted side effects, especially when used often, in high doses, or in combination. There is always the risk that a user will lose control over his or her consumption, using too much or too often.
The likelihood of developing what is now called “substance use disorder” varies by person and by drug; except in the case of nicotine, the victims of this disorder are generally a small minority among users. Most people unfortunate enough to develop a drug problem recover without formal intervention, although recovery typically comes after some struggle and several failed attempts.
But an even smaller minority faces graver problems. Their attempts to cut back fail because of withdrawal symptoms or persistent cravings; they have become addicted. Addicts, although relatively few in number, account for most of the damage done by drugs.
Some potentially habit-forming chemicals—including the two biggest killers, alcohol and tobacco—are legal to use and sell. Others are illegal or restricted to medical use by prescription. This tends to reduce the number of people who develop drug problems, but it also worsens the problems of those who do develop them. Making
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