The fifth precept covers all intoxicants, including narcotics, that alter the state of consciousness and are physiologically addictive. The danger and negative effects of narcotics, such as cocaine and heroin, are too well known to need any further elaboration. Today they represent a serious health and social problem around the world.
Drinking intoxicants is not part of the Buddhist culture, although it seems to have become a widespread phenomenon in modern society. It is true that alcoholic consumption was prevalent before and during the time of the Buddha, but he never approved of the practice. The fact that something is commonly practiced does not necessarily mean that it is good and wholesome. Those who advocate drinking as a factor for promoting friendship forget to take account of the reality that so many friendships have been drowned in those intoxicants. The brawls, strife and unruly behavior that often follow the consumption of alcoholic beverages represent an unequivocal testimony of the ignoble state to which human beings can be reduced to under the influence of intoxicants. Friendship founded on compassion and mutual understanding is much more desirable than that which is based on alcohol. Social drinking may produce a general euphoric atmosphere among drinkers (and probably a nuisance for nondrinkers), but it is never a necessary condition for interpersonal relationship. Often, people use this as an excuse to get drunk. The high rate of car accidents connected with drunk driving should serve as a strong reminder of the danger and undesirability of alcoholic consumption. On the other hand, it may be mentioned in passing that liquor does contain certain medicinal properties and can be used for medical purposes. Such use, if genuine and under qualified supervision, does not entail transgression of the fifth precept and is not considered a morally unwholesome act.
The most obvious danger of intoxicants is the fact that they tend to distort the sensibilities and deprive people of their self-control and powers of judgment. Under alcoholic influences, a person is likely to act rashly and without due consideration or forethought. Otherwise decent people may even commit murder or rape under the influence of alcohol, or cause all kinds of damage (such as fire, accident, and vandalism) to people or property. The Buddha described addiction to intoxicants as one of the six causes of ruin. It brings about six main disadvantages: loss of wealth, quarrels and strife, a poor state of health (liability to diseases), a source of disgrace, shameless and indecent behavior, and weakened intelligence and mental faculties.