The increasing pain from the nerve-killing medication may be due to the swelling and pain caused by the increased pressure in the pulp cavity of the more severe inflammation, or the reactive pain caused by the over-stimulation of the medication put in. 1. Heavy inflammation. General root canal treatment will be put into the pulp inactivator, but if the tooth inflammation is heavy, pulp cavity has inflammation oozing, put in the inactivator after the closure of the perforation hole, will impede the oozing channel, resulting in excessive pressure in the pulp cavity to produce pain. 2. Drug stimulation. There are various types of pulp inactivator, when put into the drug irritation is strong, due to individual differences, may cause the reaction to the drug pain. Putting in the drugs to kill the dental nerve will usually have a slight pain, if the pain worsens and cannot be tolerated, it is recommended to go to the hospital in time to change the drugs.