Too much... An Aspirin overdose occurs when someone takes more Aspirin than what is recommended. An intentional overdose occurs when someone takes more than what is recommended with the intent of doing harm to themselves whereas an accidental overdose occurs when there is no such intent. (for example, perhaps the person forgot that they already took a dose earlier and take another dose, etc.).
Potentially lethal. Occurs with a single dose of > 150 mg/kg or >6, 500 mg (20 regular strength tablets or 13 extra strength). Symptoms include nausea, vomiting, epigastric (abdominal) pain, rapid breathing (acidosis), ringing in the ears (tinnitus), and can lead to confusion, seizures, delirium, coma and death. Er treatment and consultation with poison control are indicated.