The death of six tourists visiting Laos is suspected to be the result of mass methanol poisoning, after all are believed to have consumed alcoholic drinks tainted with the toxic substance. With officials issuing fresh warnings about the dangers of ingesting methanol, here’s what you should know about what it is and how it affects the body.

What is methanol?

Methanol is a clear, colorless liquid classed as an alcohol. It has several uses within industry, including acting as a solvent, in the production of chemicals, as an ingredient in pesticides, and as an alternative fuel source.

However, according to the World Health Organization (WHO), it can also end up in alcoholic drinks, either accidentally when people are attempting home-brewing, or by deliberate addition to keep production costs low.

How does methanol affect the body?

While trace amounts of methanol can naturally be found in fruit juices or fermented drinks, methanol in any amount higher than that isn’t meant for human consumption.

“Methanol is like the alcohol in our drinks – colourless and odourless – but its impact on humans can be deadly. It has a different carbon atom structure which completely changes how humans process it in the body,” explained Christer Hogstrand, Professor of Molecular Ecotoxicology at King’s College London, in a comment to the Science Media Centre.

Both ethanol (the type of alcohol that’s normally found in alcoholic beverages) and methanol are broken down by the body, but in the case of methanol, this results in the production of formaldehyde, formic acid, and formates. It’s these products that are toxic to the body.

“Formate, which is the main toxin produced, acts in a similar way to cyanide and stops energy production in cells, and the brain seems to be very vulnerable to this,” said Dr Christopher Morris, a senior lecturer in the Faculty of Medical Sciences at Newcastle University. “This leads to certain parts of the brain being damaged.”

The products of methanol breakdown affect many other parts of the body too, resulting in a whole host of symptoms including vomiting, headache, visual disturbances that can include partial or total loss of vision, and difficulty breathing. In severe cases, methanol poisoning can cause convulsions, coma, and, after stopping breathing completely, death.

What amount of methanol constitutes a lethal dose depends on the individual, but according to Dr Wayne Carter, an associate professor at the University of Nottingham’s School of Medicine, it can be as little as 15 milliliters of a 40 percent solution.

Can methanol poisoning be treated?

In any case, methanol poisoning is an emergency and should be treated immediately. However, the approach to treatment can vary.

One method is the targeting of alcohol dehydrogenase, the enzyme that catalyzes the breakdown of methanol. This is also the enzyme that helps to break down ethanol – and it much prefers to do so over methanol. So, by giving patients ethanol, it can keep alcohol dehydrogenase occupied and stop the formation of methanol’s toxic byproducts.

However, in some cases, treatment may require dialysis; this is a process in which blood is diverted to an external machine, where methanol and its byproducts can be filtered out, before returning the now-filtered blood to the body. 

How can methanol poisoning be avoided?

When it comes to methanol poisoning, WHO recommends that individuals can protect themselves by:

•    Not buying alcoholic drinks from places that aren’t licensed to sell it.

•    Not buying alcoholic drinks that are unlabeled/have labels of poor quality, or that have a broken seal.

•    Being aware of the symptoms of methanol poisoning and seeking medical help immediately if they appear.

All “explainer” articles are confirmed by fact checkers to be correct at time of publishing. Text, images, and links may be edited, removed, or added to at a later date to keep information current. 

The content of this article is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of qualified health providers with questions you may have regarding medical conditions.