Emergency doctors are warning about the dangers of tainted cocktails in South-East Asia after a 19-year-old American woman was left with permanent visual impairment after consuming multiple drinks containing methanol.

The backpacker drank eight to 10 complementary cocktails at two Bali bars and arrived in New Zealand 35 hours later suffering shortness of breath and impaired vision.

When consumed, methanol can cause blindness, coma and death. 

She had consumed a local drink known as Arrack, mixed with fruit juice.

The teenager was treated at Christchurch Hospital emergency department for methanol poisoning but her vision continued to deteriorate over the next four weeks.

The case follows a similar incident last year in which a 25-year-old Australian nurse suffered brain damage and kidney failure after drinking Arrack laced with methanol, a toxic substance found in fuel, solvents and anti-freeze products.

When consumed, methanol can cause blindness, coma and death.

In 2009, 25 tourists died after drinking a contaminated batch of Arrack in Bali.

Christchurch Hospital emergency physicians Paul Gee and Elizabeth Martin said it was likely the woman drank a concoction contaminated with methanol from an illegal distillation of ethanol.

The doctors, outlining the case in the journal Emergency Medicine Australasia, said it was not uncommon for the symptoms of methanol poisoning to be delayed by up to 50 hours after consumption, as the body metabolised it.

"Most patients complain of anxiety, headache, nausea, vomiting and weakness," the doctors said.

"Visual symptoms include blurred vision, spots, photophobia and partial to complete visual loss."

Arrack is a coconut flower, rice and sugarcane-based spirit which is produced commercially and illegally in Indonesia. It is a different drink than Arak, a Middle Eastern anise-flavoured liquor.

"This case highlights the risk of consuming alcohol of unverified origin in South-East Asia," the authors said.