Cigarette smoking, both active and passive, has vastly contrasting effects on the development and progression of both Crohn’s disease (CD) and ulcerative colitis (UC). Quitting smoking also affects both forms of IBD differently. In recent years the use of e-cigarettes (vaping/vaping products) and alternative tobacco products has increased with as yet little research into the effects on IBD. As smoking and the use of other products are modifiable lifestyle factors, knowledge of their effects on IBD is therefore very important for those who care for people with IBD. The use of recreational or non-prescribed drugs in IBD has not been widely investigated. There is conflicting evidence as to the benefit of cannabis and the risks should not be underestimated. Issues of legality leave this a poorly reported area. Very brief mention will be made of alcohol consumption and IBD.