It takes from 20 minutes to 2 weeks to kill the nerve, depending on the type of treatment and the medication used. 1. Treatment method: the method of killing the nerve mainly includes direct extraction method and drug inactivation method, and the time required is different. If the nerve is extracted with an extraction needle, the time required is relatively short, usually about 20-30 minutes; if the nerve is killed with drug inactivation method, the time required is longer, depending on the type of drug, it may take from 2 days to 2 weeks. 2. Selection of drugs: If you choose the drug inactivation method to kill the nerve, according to the differences in the choice of drugs, the time required is different. If you choose arsenic trioxide treatment, it may take 2 to 4 days to kill the nerve; if you choose arsenic-free inactivation agent, it will take longer, and it may take 10 days to two weeks. After killing the nerve, you should take good oral care and keep your mouth clean and hygienic. If persistent tooth pain occurs after killing the dental nerve, you should go to the hospital for review, make a clear diagnosis and carry out treatment as early as possible.