Why is methanol dangerous if swallowed or inhaled in large amounts?

Methanol is a highly toxic substance that poses severe health risks if swallowed or inhaled in significant amounts. While methanol itself is dangerous, its toxicity is largely driven by the body's metabolic response to it.12

When ingested or inhaled, the body attempts to detoxify methanol by oxidizing it using the enzyme alcohol dehydrogenase. This process converts methanol into formaldehyde, which is subsequently oxidized into formic acid. Both of these metabolic products are significantly more toxic than methanol itself.2

The accumulation of formic acid in the body leads to acidosis—a condition where the body's pH drops below its normal level—and can cause permanent damage, including blindness and death. Other symptoms of methanol poisoning include headache, nausea, vomiting, abdominal pain, central nervous system depression, and shortness of breath. Because of these extreme risks, methanol exposure is considered a medical emergency.132