Symptoms of methanol toxicity may not appear for 12 to 24 hours after ingestion until toxic metabolites accumulate. Time to symptom onset may be longer if ethanol is consumed, as ethanol inhibits methanol metabolism. Signs and symptoms include CNS depression, visual disturbances (classically, a complaint of looking at a snowstorm), abdominal pain, nausea, and vomiting. The gastrointestinal symptoms may be due to mucosal irritation or pancreatitis. Funduscopic examination may reveal retinal edema or hyperemia of the optic disk.
Ethylene glycol poisoning often exhibits three distinct clinical phases after ingestion. First, within 12 hours, CNS effects predominate: the patient appears intoxicated without the odor of ethanol on the breath. Second, 12 to 24 hours after ingestion, cardiopulmonary effects predominate: elevated heart rate, respiratory rate, and blood pressure are common. Congestive heart failure, respiratory distress syndrome, and circulatory collapse may develop. Third, 24 to 72 hours after ingestion, renal effects predominate which are characterized by flank pain, costovertebral angle tenderness, and acute tubular necrosis with acute renal failure. Hypocalcemia may result from precipitation of calcium oxalate into tissues leading to tetany and typical ECG changes.