What dosage of aspirin is lethal for adults?

Taking a dose of aspirin over 150 milligrams per kilogram is potentially fatal for adults, and children are affected at lower doses, according to MedlinePlus. Overdosing on a large, single dose of aspirin, purposely or accidentally, is known as an acute overdose.

Symptoms of an aspirin overdose include ringing in the ears, dizziness, seizures and coma, notes MedlinePlus. Anyone suspecting an aspirin overdose needs to call a poison control center and visit an emergency room immediately. Symptoms generally worsen as the level of aspirin rises in the blood, unless the patient receives medical treatment quickly. Treatment for an overdose includes using activated charcoal, fluids and laxatives.