Tylenol with codeine can be very constipating. On the other hand antibiotic use can cause diarrhea. My advice is to use plain tylenol for the pain. Bite down on cooled tea bags. and take a lot of probiotics while on penicillin. Also check with your dentist. They only gave me antibiotics as a prophylactic measure to prevent infection. I told him that I wouldn't take antibiotics for that reason. He said okay. I never had a problem after my wisdom tooth was extracted. Those of us with IBS or IBD have to be very careful of antibiotics.