Travellers are being warned of the dangers of methanol poisoning after six tourists to Laos have died.
Methanol is an industrial chemical found in antifreeze and windshield washer fluid.
It's not meant for human consumption and is highly toxic.
Drinking even small amounts can be damaging. A few shots of bootleg spirit containing it can be lethal.
Poisoning is a medical emergency and should be treated in hospital.
There are drug treatments that can be given, as well as dialysis to clean the blood.
Some cases can be treated using alcohol (ethanol) to outcompete the methanol metabolism. But this has to be done quickly.
Prof Alastair Hay, an expert in environmental toxicology from the University of Leeds, explained: "Ethanol acts as a competitive inhibitor largely preventing methanol breakdown, but markedly slowing it down, allowing the body to vent methanol from the lungs and some through the kidneys, and a little through sweat.”
Dr Hovda said getting help quickly after consuming methanol was crucial to chances of surviving.
"You can ease all affects if you get to hospital early enough and that hospital has the treatment needed," he said.
"You can die from a very small proportion of methanol and you can survive from a quite substantial one, if you get to help.
"The most important antidote is regular alcohol."
MSF says the majority of methanol poisonings happen in Asia, but some also occur in Africa and Latin America.
The advice for travellers is to know what you’re drinking and be aware of the risks.
Drink from reputable, licensed premises and avoid home-brewed drinks or bootleg spirits.
Methanol is produced during the brewing process and concentrated by distillation.
Commercial manufacturers will reduce it to levels which are safe for human consumption. However, unscrupulous backyard brewers or others in the supply chain may sometimes add industrially produced methanol, to make it go further and increase profits.
Dr Hovda said methanol was mixed into alcohol "mostly for profit reasons, because it's cheaper and easily available".
It is also possible for high levels of methanol to be produced by contaminating microbes during traditional ethanol fermentation.
The UK Foreign Office advises travellers: "Take care if offered, particularly for free, or when buying spirit-based drinks. If labels, smell or taste seem wrong then do not drink."
Affected drinks may include:
To protect yourself from methanol poisoning:
Seek urgent medical attention if you or someone you are travelling with show signs of methanol poisoning.