Hi.. Can understand your concern.. First of all I would like to tell you that smoking weed or any other form of recreational drug is very harmful for health as it can cause serious CARDIO-PULMONARY DISEASES as well as is responsible for LUNG AND ORAL CANCER. Now as per your query smoking weed should be ceased before one week or so before surgery and if you are asked not to smoke 48 hours before surgery it is just to keep the tissues in non inflamed and non injured state as smoking leads to inflammation of tissues due to heat as well as it causes shrinkage of blood vessels. Due to inflammation there can be more bleeding during the procedure leading to more blood loss as well as difficulty in performing the surgery and shrinkage of blood vessels can lead to post surgery complications like delayed healing due to reduced blood supply in that area. Due to delayed healing there are increased chances of infections which can cause complications. In case of wisdom tooth there can be dislodgement of clot if you smoke after the surgery leading to a very painful condition known as Dry Socket in which healing does not take place leading to pain, foul smell,lethargy and at times fever. If you are going to get i.v sedation the weed can lead to interference with the anaesthesia. You should definitely avoid smoking before surgery as well as avoid smoking 10 to 15 days after surgery too for better healing. Hope your query is solved.. If you find the answer helpful please write a positive review and click on find this answer helpful as a token of appreciation.. Thanks and regards.. Dr.Honey Nandwani Arora.