SIDE EFFECTS: Nausea, vomiting, constipation, lightheadedness, dizziness, drowsiness, dry mouth, flushing, sweating, vision changes, or mental/mood changes may occur. If any of these effects persist or worsen, notify your doctor or pharmacist promptly. Tell your doctor immediately if any of these unlikely but serious side effects occur: slow/irregular breathing, slow/irregular heartbeat, change in the amount of urine. A serious allergic reaction to this drug is unlikely, but seek immediate medical attention if it occurs. Symptoms of a serious allergic reaction include: rash, itching, swelling, severe dizziness, trouble breathing. If you notice other effects not listed above, contact your doctor or pharmacist.
Tylenol 3 does contain codeine, which a fair number of people are allergic to (or at least have a reaction to). You should probably just take extra strength Tylenol (without the codeine) to see if it helps with the pain without the rash.