Overdose on acetaminophen. I took too many 5mg hydrocodone's with 500mg acetaminophen in each of them. This lead me to take 15,000mg of acetaminophen in less than 24 hours. I was throwing up uncontrollably and took myself to the ER. To note: I had an adverse reaction to the NAC flush and developed hives on my face. They went away with a bit of Benadryl.