How long should I be taking tylenol for? I'm seeing a doctor tomorrow about a recurring (sinus-caused, I think?) headache, so I will for certain as him/her. It's been over a week since the headaches started and they've shown NO sign of easing up. I started taking tylenol once at night about Wednesday, but over the last couple days I've had to start taking a dose two or three times a day. How long should I be taking tylenol for, if the pain doesn't go away?