What happen when you overdose with paracetamol?

depends how much.... anything up to about 12 tablets in a day nothing will happen, from 12-20 you'd probly feel sick and maybe have a headache and feel dizzy. over 20 tablets for a small to average size person and you are getting toward toxic levels. severe paracetamol overdose can cause liver failure if not treated within the first 12-24 hours.