Smoking after wisdom teeth extraction may cause negative pressure in the oral cavity leading to the dislodgment of the blood clot, causing post-extraction reactive pain, post-extraction bleeding, dry socket and other complications, as follows. 1. Post-extraction reactive pain: the nerve endings on the alveolar bone wall are exposed after the blood clot is dislodged, and pain symptoms will appear when stimulated by the outside world. 2. Bleeding after tooth extraction: the blood clot will cause bleeding from the broken blood vessels after dislodging, and if the blood flows into the adjacent tissue space, it will cause ecchymosis or hematoma. 3. Dry socket: The wall of the alveolar bone exposed after the blood clot is dislodged can be necrotic in many places, resulting in dry socket. If any of the above symptoms occur, it is recommended to go to the hospital in time to receive professional treatment as soon as possible.