The general rule in Islam is that any beverage that get people intoxicated when taken is unlawful, both in small and large quantities, whether it is alcohol, drugs, fermented raisin drink, or something else.
In his book Al-HalalwalHaramfil Islam (The Lawful and the Prohibited in Islam)Sheikh Yusuf Al-Qaradawi states the following: The first declaration made by the Prophet (peace and blessings be upon him) concerning this matter was that not only is Khamr (wine or alcohol) prohibited but that the definition of Khamr extends to any substance that intoxicates, in whatever form or under whatever name it may appear. Thus, beer and similar drinks are haram.
The Prophet (peace and blessings be upon him) was once asked about certain drinks made from honey, corn, or barley by the process of fermenting them until they became alcoholic. The Prophet (peace and blessings be upon him) succinctly replied, “Every intoxicant is Khamr, and every Khamr is haram.”Reported by Muslim.)
And `Umar (may Allah be pleased with him) declared from the pulpit of the Prophet (peace and blessings be upon him) that “Khamr is that which befogs the mind.”(Reported by Al-Bukhari and Muslim.)
Islam takes an uncompromising standing prohibiting intoxicants, regardless of whether the amount is little or much. If an individual is permitted to take but a single step along this road, other steps follow; he starts walking and then running, and does not stop at any stage. That is why the Prophet (peace and blessings be upon him) said, “Of that which intoxicates in a large amount, a small amount is haram.”(Reported by Ahmad Abu Dawud and At-Tirmidhi.) And again, “If a bucketful intoxicates, a sip of it is haram.”(Reported by Ahmad, Abu Dawud and At-Tirmidhi.)
Prohibition of Drugs:
“Khamr is what befogs the mind.” These are the words spoken by `UmarIbn Al-Khattab (may Allah be pleased with him) from the pulpit of the Prophet (peace and blessings be upon him) providing us with a decisive criterion for defining what falls under the prohibited category of khamr. There remains then no room for doubts and questions: any substance which has the effect of befogging or clouding the mind, impairing its faculties of thought, perception, and discernment is prohibited by Allah and His Messenger (peace and blessings be upon him) and will remain so until the Day of Judgment.
Drugs such as marijuana, cocaine, opium, and the like are definitely included in the prohibited category of khamr. It is well known that the use of such drugs affects the sensory perceptions, making what is near seem distant and what is distant seem near; that their use produces illusions and hallucinations, so that the real seems to disappear and what is imaginary appears to be real; and that taking drugs in general impairs the faculty of reasoning and decision-making. Such drugs are taken as a means of escape from the inner reality of one’s feelings and the outer realities of life and religion into the realm of fantasy and imagination.
added to this psychological fact are the physical effects: bodily lassitude, dullness of the nerves, and decline in overall health. The moral consequences, moral insensitivity, weakening of the will power, and neglect of responsibilities are also well known. Eventually, drug addiction weakens a person and makes him a diseased member of society. Furthermore, drug addiction may result in the destruction of the family or even drive one to a life of crime. Since obtaining drugs involves a great outlay of money, drug addiction may take its toll on the family budget and even it may tempt the drug addict to resort to illegal means to pay for drugs.
When we recall the principle that all impure and harmful things have been made haram, there can be no doubt in our minds concerning the prohibition of such detestable substances such as drugs, which cause so much physical, psychological, moral, social and economic harm.
Muslim jurists are unanimous on the prohibition of those drugs which were found during their respective times and places. Foremost among them was Sheikh al-Islam IbnTaymiyyah, who said: “This solid grass (hashish) is haram, whether or not it produces intoxication. Sinful people smoke it because they imagine it producing rapture and delight, an effect similar to drunkenness. While wine makes the one who drinks it active and quarrelsome, hashish produces dullness and lethargy; furthermore, smoking it disturbs the mind and temperament, excites sexual desire, and leads to shameless promiscuity, and these are greater evils than those caused by drinking. This perverted habit has spread among the people after the coming of the Tartars. The hadd (prescribed punishment) for smoking hashish, whether a small or large amount of it, is the same as that for drinking wine, that is, eighty or forty lashes.
He explained the imposition of hadd for smoking hashish in the following manner: It is the rule of the Islamic Shari’ah that any prohibited thing which is desired by people, such as wine and illicit sexual relations, is to be punished by imposing hadd, while the violation of a prohibited thing which is not desired, such as (eating) the flesh of a dead animal, calls for Ta’zeer (disciplinary punishment). Now hashish is something desired and craved for, and it is hard for the addict to renounce it. Accordingly, the application of the texts of the Qur’an and Sunnah to hashish is similar to that of wine. (FatawaIbnTaymiyyah, vol. 4, p. 262. Also see his book, As-Siyasah Ash-Shar’iyyah.)