All perfect praise be to Allah the Lord of the Worlds. May Allah`s peace and blessings be upon our Prophet Mohammad and upon all his family and companions.
Sharia came to achieve great objectives that preserve religion and essentials of life. One of these objectives, as agreed by the scholars, is self-preservation, so it banned all that is harmful and impure. Allah Says regarding the purpose behind sending Prophet Mohammad (Peace and blessings be upon him): "he allows them as lawful what is good (and pure) and prohibits them from what is bad (and impure). " {Al-`Araf, 157}.
Moreover, Prophet Mohammad (Peace and blessings be upon him) said: "There should be neither harming nor reciprocating harm." {Musnad Ahmad, Hadith No.(1/313).
Following the progress achieved in the experimental sciences as well as modern medicine, people came to know that tobacco products contain extremely harmful and toxic chemicals that cause serious diseases, be that on the short run or the long run, and this is by agreement of physicians.
In conclusion, it isn`t allowed to smoke hookah. On the contrary, it should be avoided to eliminate its harm on society, and this can be achieved through fearing Allah, first and foremost, and cooperation between members of society and people in charge. And Allah The Almighty Knows Best.