Hi. Thanks for posting your concern at HCM. Hair fall has not yet been proven to be a side effects of smoking. Hair fall can be due to various causes: -Non scaring hair loss: Androgenetic alopecia, Telogen efluvium, Alopecia areata etc -Primary cicatricial alopecia: Lichen plano pilaris, Discoid lupus erythematosus etc -Secondary cicatricial alopecia: Folliculitis decalvans, dissecting cellulitis of the scalp etc It is important to ascertain the exact cause of hair fall in order to help it better. Collitis OR any other severe illness stress can precipitate telogen effluvium which usually begins 2-3 months later and can continue for more than 6 months (chronic telogen effluvium) if the underlying organic cause (collitis)of hair loss is not corrected. So, Underlying collitis could be a cause of your hair loss if it is still continuing. take care regards