Substance
Acetaminophen

Pathology
Production of toxic intermediate metabolite that cannot be detoxified due to glutathione depletion.

Symptoms
Phase 1 (0–24 hr): Sometimes asymptomatic—anorexia, nausea, vomiting.
Phase 2 (24–48 hr): GI symptoms resolve; hepatotoxicity is subclinical, but liver function tests and coagulation tests are abnormal. If liver damage is significant, patient may progress to phase 3.
Phase 3 (48–96 hr): Problems due to severe hepatic compromise—bleeding disorders, hypoglycemia, hepatic encephalopathy.
Phase 4 (>96 hr): Recovery period. Laboratory values return to normal and symptoms resolve.

Emergency Measures
Administer activated charcoal. Toxicity is unlikely at a dose <140 mg/kg. For significant serum levels of acetaminophen, acetylcysteine can be administered orally in a loading dose followed by a maintenance regimen.

Comments
Patients with toxic levels of acetaminophen 4 hr after ingestion require hospitalization for observation and supportive measures. Hepatic failure can occur several days after the ingestion, and renal complications or failure can also develop. Most patients recover fully without further sequelae. In some instances, hepatic failure may require transplantation. Check acetaminophen levels routinely in patients with any oral overdose.