What are the Islamic rulings and guidelines regarding narcotics, to what extent do they affect the religious aspect of the user, is it permissible to use them for treatment, and what acts of worship might a drug user neglect?

The prohibition of narcotics is based on religious texts that forbid all evil things and intoxicants, such as Allah's saying: "And He makes lawful for them the good things and prohibits for them the evil things," and the Hadith: "Every intoxicant is Khamr, and every intoxicant is forbidden." Weak religious deterrence is a primary reason for falling into this sin. Repentance from drug use is acceptable, and the one who repents is like one who repents from drinking Khamr. As for gradual treatment with quantities of the drug, it is permissible out of necessity if specialized doctors determine it, but the default is prohibition, and they must sincerely strive to gradually rid themselves of it. A drug user may abandon acts of worship like prayer due to the absence of reason, and their performance of it while intoxicated is not valid. The prayer of one who drinks Khamr is not accepted for forty days, but their repentance is accepted.