Haram Drugs
What has been made impermissible is khamar in Quran verses 2:19 and 5:90 which refers to intoxication. Alcohol generally causes intoxication, hence in application it has been made impermissible as a sadd-e-zariya . Apart from alcohol, any substance that can cause one intoxication would be termed as impermissible using the principle of qiyas .