Nausea after root canal may be related to temporomandibular joint disorder caused by opening the mouth for too long for root canal treatment, or cervical spondylosis attack caused by lying down for too long, or it may also be related to extravasation of therapeutic drugs during root canal treatment. According to different causes, local treatment, physical therapy, drug treatment and other measures can be taken. 1. Temporomandibular joint disorder: During root canal process, patients need to open their mouths widely to facilitate the operation of physicians. The long time of opening the mouth can lead to joint disorder, which is manifested as restriction of opening the mouth, popping sound, local pressure pain, and some patients are accompanied by headache, nausea and other uncomfortable symptoms. At this time to take rest, local physical therapy and other measures. 2. Cervical spondylosis attack: If the patient himself has cervical spondylosis, in the process of root canal treatment, the patient may be too long lying down can be induced by cervical spondylosis attack, manifested as dizziness, nausea, do not want to eat, atypical migraines and so on. At this time, rest, bed rest, neck physiotherapy or traction, etc. If necessary, non-steroidal anti-inflammatory analgesics (such as celecoxib, diclofenac) and vitamin B, methylcobalamin and other nutritive nerve drugs can be applied. 3. Drug extravasation: In the process of root canal treatment, root canal disinfectant and root canal filling agent are commonly used. When the sealing drug or root canal filling is not tight, it can lead to extravasation of drugs, causing nausea and discomfort. At this time, you can rinse your mouth and brush your teeth to dilute the taste of the medication; if necessary, you can return to the stomatology department to have the root canal sealed and filled again. After the root canal nausea and long time can not be relieved, should be timely consultation, improve the examination, clear cause and diagnosis, under the guidance of professional physicians for standardized treatment.