Travellers partying it up in Bali are warned to watch what they drink after a backpacker was left with damage to her vision after accepting a complimentary cocktail containing methanol.

Emergency doctors have advised the 19 year old backpacker was poisoned and received permanent damage to her vision after drinking at a popular tourist bar in the island destination.

Her drink contained a mixture of the local alcohol Arrack, a coconut flower rice and sugarcane spirit, and fruit juice, and was most likely contaminated with local 'moonshine' alcohol containing methanol.

Generally used as a fuel, antifreeze and to de-ice windscreens, methanol toxicity can lead to blindness, coma and even death.

In 2009, 25 people died from methanol poisoning in Indonesia.  An Australian tourist was poisoned in almost identical circumstances in 1992.

This recent case highlights the risk of consuming alcohol of unverified origin, according to the doctors that dealt with this case.

Symptoms include: anxiety, headaches, nausea, vomiting, weakness and blurred vision.