text: how long will my mouth hurt after root canal? i had to go to the dentist this morning because i had toothache, he said the tooth was badly decayed and he had to do a root canal on it. the local anaesthetic has worn off now and it's quite painful - not like the terrible toothache i had before, more of a dull achey pain. i know it's probably just because of the work that was done on the tooth, but how long should i expect it to last for? and can i take pain killers for it? what's best to take? call him back and tell him you're in pain.  he should have prescribed something in the first place.  my dentist gave me 800mg motrin, which is basically super-strength advil.  it'll be achy for 2-3 days.  he should have instructed you to call him back if it still hurts after a week.    seriously, medical care has dwindled in the last 10 years.  what is up with doctors forgetting to tell their patients important information like this?