I took 4 extra strength tylenol (acetaminophen) in 4 hours is that ok ?

Not ok: Directions state: "take 2 caplets every 6 hours while symptoms last." Take medications per directions unless your physician specifies differently. Take care.

Probably OK: Extra strength Tylenol (acetaminophen) are 500 mg, so 4 of them is 2000 mg. The usual safe recommended maximum daily dose is 3000 mg in 24 hours. If there is underlying liver or kidney disease or other medications that interact, even 2000-3000 mg can be too much. The other issue to consider is the need for Tylenol (acetaminophen). If there is a new pain that needs to be evaluated, see your doctor.

Yes: Sometimes high doses are required, like for migraine, but limit to 4g total in a day (which you hit if they are 500s, a little over with 650 but still ok if you don't take any more).