Question:
Is smoking shisha permissible?
Answer:
In the Name of Allah, the Most Gracious, the Most Merciful.
As-salāmu ‘alaykum wa-rahmatullāhi wa-barakātuh.
Research by the British Heart Foundation shows that during a typical hour-long shisha session, one can inhale the same amount of smoke equivalent to more than 100 tobacco cigarettes.[1]
Though shisha smoking has become modernised via the use of flavoured fruits and juice, there’s still one component found in the water pipe – tobacco.
The tobacco contains 2 times the levels of carbon monoxide and 3 times the level of nicotine when compared to cigarettes.
The charcoal that is used to light up the tobacco contains toxins.
Shisha contains high levels of carbon monoxide and nicotine and this has a high potential to result in brain malfunction or unconsciousness.
Shisha contains chemicals such as cadmium, cobalt and arsenic. If there’s one disease linked with cadmium then that’s cancer. The cancer common from smoking is cancer of the lungs, mouth or gums. 
Women who smoke shisha have a high chance of delivering premature babies (with breathing difficulties).
The aluminium foil used when burning the charcoal produces carcinogenic fumes. This again leads to cancer.
Smoking increases blood pressure levels and of course the risk of a heart attack.
Smoking a shisha pipe in a non-ventilated room could result in light headaches for anyone in the room, whether smoking or not.[2]
Hours are wasted sitting in cafes and smoking shisha.  Such sessions are further polluted with gossip, heedlessness, intermingling and many other evils.  A shisha session is a bombardment and shelling upon the body and soul.      
Anything which has such collateral damage on the body and soul will be severely disliked and prohibited. Thus, to smoke shisha is Makruh Tahrīmī (severely disliked).[3] 
And Allah Ta’ālā Knows Best
Mufti Faraz al-Mahmudi,
Darul Iftaa
Dublin, Ireland
www.darulfiqh.com