It can also be inadvertently generated during brewing.
The Ministry of Foreign Affairs and Trade (MFAT) earlier said a New Zealand citizen was thought to be one of the poisoning victims.
Today a spokeswoman confirmed the tourist has been able to return to New Zealand.
“The New Zealand Embassy in Bangkok [which has responsibility for Laos] has been providing assistance to one New Zealander who we believe to have been poisoned with methanol in Laos,” she said.
“They have now departed Laos and returned home.”
Mfat has updated its travel advisory for Laos to note there have been several cases of suspected methanol poisoning after consuming alcoholic drinks.
“Travellers are advised to be cautious about consuming alcoholic beverages, particularly cocktails and drinks made with spirits that may have been adulterated with harmful substances. Know the signs of methanol poisoning and seek immediate medical attention if poisoning is suspected.”
It’s understood the owner of the Nana Backpacker Hostel where the two friends had been staying was detained on Friday for questioning by police in Laos, according to the ABC.
The two Australian victims are believed to have started their night with free drinks at the hostel before heading out to other bars.
The ABC reports the hostel previously claimed the drinks in question did not come from its bar.
What does methanol poisoning do?
Victims can go into severe metabolic acidosis, when too much acid builds up in the body.
Symptoms include nausea, vomiting, and abdominal pain, as well as depression of the central nervous system. This can cause people to become unconscious and potentially enter a coma.
Methanol poisoning can also cause retinal damage, leading to vision loss.
Treatment includes supportive care such as intubation and ventilation to help the patient breathe, and some medicinal care may be provided to remove methanol from the body.
Melissa Nightingale is a Wellington-based reporter who covers crime, justice, and news in the capital. She joined the Herald in 2016 and has worked as a journalist for 10 years.