The UK’s Foreign, Commonwealth and Development Office (FCDO) has issued a warning over a destination hugely popular with Brits.

Almost a million people from the UK are believed to visit India each year, and on Tuesday, November 18, the FCDO amended its travel guidance for people heading to the South Asian nation.

Travellers heading to India are now being warned: “There has been an increase in cases of serious illness caused by alcoholic drinks containing methanol in popular travel destinations around the world. Even small amounts of methanol can kill. It is not possible to identify methanol in alcoholic drinks by taste or smell.”

Further guidance on the Government’s Travel Aware website adds: “Methanol is toxic even in small amounts. It is an industrial alcohol made from distilling wood and can be found in many commercial products, like antifreeze, fuel and paint thinners.

“In some parts of the world methanol products are sometimes illegally mixed with ‘real’ alcohol such as spirit-based drinks and cocktails.”

Spotting methanol poisoning can be difficult because at first it can affect you in the same ways as ‘real’ alcohol. However, some early signs to watch out for include vomiting, poor judgement, loss of balance and drowsiness.

Between 12 and 48 hours after drinking, a person may experience abdominal pain, vertigo, hyperventilation, breathlessness, blurred vision and/or blindness, coma and convulsions. If you or someone you are travelling with have any of these symptoms seek urgent medical attention.

Vision issues are a red flag and can also appear 12-48 hours after the first drink, as per Government guidance. Methanol poisoning can cause blurry vision, trouble looking at bright lights, and in some cases complete blindness.

If you have “snowfield vision” (seeing snowy static like an old TV) or tunnel vision seek urgent medical help. Other countries with FCDO methanol poisoning warnings are Ecuador, Kenya, Japan, Mexico, Nigeria, Peru, Uganda, Russia, Cambodia, Indonesia, Turkey, Costa Rica, Thailand, Vietnam, Laos and Fiji.