Methanol is extremely dangerous. Even small amounts can cause delayed poisoning, blindness, severe acidosis, coma, and death , and symptoms may not appear for 6 to 24 hours after exposure.

Why it is so dangerous

Methanol itself is harmful, but the body turns it into formaldehyde and formic acid , which are the main causes of toxicity. That delay can make people think they are fine at first, while serious damage is still developing.

Common warning signs

  • Nausea, vomiting, and abdominal pain.
  • Headache, dizziness, confusion, and reduced coordination.
  • Blurred vision, “halo” vision, light sensitivity, or vision loss.
  • Rapid breathing, severe metabolic acidosis, coma, or seizures in severe cases.

How much can be harmful

Reported severe injury has occurred from as little as 4 to 15 mL in some cases, including irreversible optic nerve damage. A dose around 1 g/kg is considered potentially lethal in adults, though exact effects depend on the person, timing, and whether ethanol was also involved.

What to do

If someone may have swallowed methanol, treat it as an emergency and seek urgent medical care right away, even if they feel okay at first. Early treatment matters because outcomes can worsen