Swelling of half of the face after root canal treatment usually requires a new root canal treatment, which is divided into two situations: during the root canal treatment process and at the end of the root canal treatment. 1. If half of the face is swollen during root canal treatment, it usually occurs after root canal cleaning, which may be due to excessive stimulation of the root tip during the treatment process, or stimulation of the root canal disinfection medication, etc. It is recommended to remove the temporary sealing material and then carry out root canal rinsing, reseal the medication, and at the same time, take anti-inflammatory medication orally as prescribed by the doctor, such as Cefuroxime, Cefixime, and other cephalosporins, and then continue the root canal treatment after the swelling has been eliminated. 2. If the face is swollen after root canal treatment, it means that the root canal treatment fails, which may be due to the omission of root canal, apical overfilling, tooth fracture, etc. It is recommended to re-root canal treatment or apical surgery after anti-inflammatory treatment, and if the tooth is fractured, it may need to be extracted. It is recommended to go to the stomatology department of a regular hospital for consultation, and after examination by a physician, the cause of the disease will be treated according to the cause.