Most contemporary scholars and medical councils hold that smoking is haram, because of its proven harm and the command not to destroy oneself (4:29, 2:195) and that the Prophet ﷺ made lawful only the good things (7:157). Some earlier scholars, before the harm was known, called it disliked (makruh). Today the harm is clear, so avoiding it is the safer and sounder position.
اى كسانى كه ايمان آوردهايد، اموال يكديگر را به ناحق مخوريد، مگر آنكه تجارتى باشد كه هر دو طرف بدان رضايت داده باشيد. و خودتان را مكشيد. هر آينه خدا با شما مهربان است.
آنان كه از اين رسول، اين پيامبر امى كه نامش را در تورات و انجيل خود نوشته مىيابند، پيروى مىكنند-آن كه به نيكى فرمانشان مىدهد و از ناشايست بازشان مىدارد و چيزهاى پاكيزه را بر آنها حلال مىكند و چيزهاى ناپاك را حرام و بار گرانشان را از دوششان برمى دارد و بند و زنجيرشان را مىگشايد. پس كسانى كه به او ايمان آوردند و حرمتش را نگاه داشتند و ياريش كردند و از آن كتاب كه بر او نازل كردهايم پيروى كردند، رستگارانند.
This is general information, not a fatwa. For your own situation, ask a qualified scholar.
Questions about halal and haram
Is smoking haram?
Most contemporary scholars and medical councils hold that smoking is haram, because of its proven harm and the command not to destroy oneself (4:29, 2:195) and that the Prophet ﷺ made lawful only the good things (7:157). Some earlier scholars, before the harm was known, called it disliked (makruh). Today the harm is clear, so avoiding it is the safer and sounder position.