Kiwis visiting Laos should be cautious of consuming alcoholic beverages, the Ministry of Foreign Affairs and Trade says.
The updated travel advisory comes after several cases of suspected methanol poisoning from alcoholic drinks.
Five people have reportedly died of poisoning in the country bordering Thailand, and a New Zealander is also unwell.
MFAT said travellers should be cautious about consuming alcoholic beverages, particularly cocktails and drinks made with spirits that may have been adulterated with harmful substances.
It is urging travellers to become familiar with the signs of methanol poisoning and seek immediate medical attention if poisoning is suspected.
New Zealander thought to be ill from methanol poisoning in Laos
'A very tragic story'
Monash University's department of forensic medicine Professor David Ranson told Checkpoint that "this is a very tragic story".
The acid that forms with methanol is what caused the most harm, he said.
"It's the formic acid that causes so many problems, so this is an agent that actually kills cells and as a result it causes really quite significant damage to the body."
"Quite often it takes a day or so for these symptoms to come on, particularly if the source of the methanol has been essentially combined with ethanol."
A lethal dose could be quite small, Ranson said.
"It depends on the amount that's in the drink, actually it's a surprisingly a small amount.
"Even 20-30mls can be really quite dangerous and in some people that could be fatal.
"In fact quite often people finish up having more than that, simply because if they're having several drinks that are all contaminated, it all adds up."
Ranson said there are remedies that can help if they are given in time for methanol poisoning.
"There are some treatments specifically designed to block the enzyme in the body, so that the methanol will not get broken down and cause these nasty agents to be produced.
"And if you can do that fairly early on you can keep the level of these nasty chemicals down, and people will then have a much better chance of survival."
Ranson said the most important thing if you suspect methanol poisoning is, "you have to get to hospital right away."
Checkpoint spoke to the New Zealand Drug Foundation and its principal science adviser said there are no off the shelf rapid tests for methanol in drinks.
The foundation's advice is to only drink canned or bottled drinks with a seal when travelling in Southeast Asia.
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