Symptoms of acetaminophen overdose may take many days to appear, and even when they become apparent, they may mimic flu or cold symptoms. The current maximum recommended adult dose of acetaminophen is 4,000 milligrams per day, To avoid exceeding that dose: 1  don't take more than one OTC product containing acetaminophen,2  don't take a prescription and an OTC product containing acetaminophen, and.ymptoms of acetaminophen overdose may take many days to appear, and even when they become apparent, they may mimic flu or cold symptoms. The current maximum recommended adult dose of acetaminophen is 4,000 milligrams per day, To avoid exceeding that dose: 1  don't take more than one OTC product containing acetaminophen,