Version July 2025
| Stage | Hours after ingestion | Clinical features |
| I | 0.5 to 24 hours | Nausea, vomiting, diaphoresis, pallor, lethargy, and malaise |
| Some patients remain asymptomatic | ||
| Laboratory studies are typically normal | ||
| II | 24 to 72 hours | Stage I symptoms resolve |
| Hepatotoxicity and nephrotoxicity become evident | ||
| Right upper quadrant pain, liver enlargement and tenderness | ||
| Elevation of aminotransferases occurs within 36 hours of ingestion in patients with hepatic injury | ||
| Elevation of prothrombin time (PT) and internationalized ratio of PT | ||
| Oliguria, abnormalities of renal function | ||
| Elevation of serum amylase with or without clinical pancreatitis may occur | ||
| III | 72 to 96 hours | Liver enzyme and function abnormalities peak (enzymes may be >10,000 IU/L) |
| Recurrence of Stage I symptoms | ||
| Jaundice, hepatic encephalopathy, hyperammonemia, bleeding diathesis, hypoglycemia, lactic acidosis | ||
| Renal failure, the incidence of which is related to the severity of intoxication | ||
| Death, from multi-organ failure, occurs most commonly in this stage | ||
| IV | 4 to 14 days | Recovery phase |
| Symptoms and laboratory values may not normalize for several weeks | ||
| Histologic recovery lags behind clinical recovery and may take up to three months |
