Is hookah haram?
بِسْمِ اللهِ الرَّحْمنِ الرَّحِيْم
In the name of Allah, the Gracious, the Merciful
Regarding your question on hookah, the nature of the ruling will differ based on different scenarios:
Firstly, if the hookah instrument is vaporizing an impure or intoxicating substance such as cannabis, opium, black henbane, etc., then smoking hookah will be haram (impermissible).
Secondly, if the hookah is tobacco-free, nicotine-free and even smoke-free and only produces flavoured vapour and stream, then making use of this type of hookah would be permissible although discouraged, as this usually entails going to hookah cafes, intermingling of the genders, imitating the non-believers, wasting one's time etc.
Lastly, if the hookah is tobacco-based, then although it is permissible in essence, smoking it would be makruh (disliked) due to external factors such as:
1. It is harmful to one’s health
2. It produces bad odour which disturbs others
3. It can cause addictiveness
4. Using it usually entails going to hookah cafes, imitating the non-believers in their act of being heedless of Allāh Ta’ālā, etc.
Maulānā Rashīd Ahmad Gangōhī, Maulānā ‘Abdul Hayy Lucknawī, Muftī ‘Azīzur Rahmān, and Muftī Shafī’ all deem the smoking of tobacco to be makrūh tanzīhī. Maulānā Ashrah ‘Alī Thānwī deems it makrūh and adds that it will be tanzīhī or tahrīmī based on external factors. In other words, if its usage results in more harm and sin, then the severity of its ruling will increase.
Only Allāh knows best
Written by Alimah Sabrina al-Faarsiyyah
Checked and approved by Mufti Mohammed Tosir Miah
Darul Iftā Birmingham
 Allamah Ibnu Abidin, Raddul Muhtar V.10 Pg. 46, Al-Maktabah Al-Ashrafiyyah
 Ibnu Nujaym, Al-Ashbah Wan-Nadhair, Pg.69, Qadimi Kutub Khan
 Mufti Abdurrahim Lajpuri, Fatawa Rahimiyyah, V.10 Pg.211, Darul Isha’ah