Methanol Poisoning

Key points

• • Methanol (methyl or wood alcohol) is itself only mildly harmful, but the body turns it into formaldehyde and then formic acid, which are very toxic.
• • It is most often taken by accident in illicitly distilled or adulterated liquor, sometimes causing mass poisonings.
• • After a delay of several hours, the build-up of formic acid causes a severe metabolic acidosis and damages the tissues.
• • Its most feared effect is optic-nerve damage from the formic acid, causing blurred vision and then blindness, classically likened to standing in a snowfield.
• • Other features include headache, vomiting, abdominal pain, rapid breathing (from the acidosis) and, in severe cases, coma and death.
• • At autopsy there may be congestion and swelling of the brain and damage to the optic nerves, and methanol and formic acid can be measured in the blood.