A 'super-erection' coffee laced with Viagra that can cause people to go blind has been banned in Thailand.

Gomax Coffee, which is billed as a sexual performance enhancer for men, was found to contain Sildenafil - more commonly known as Viagra, Thailand's Food and Drug Administration reported on November 14.

The drug is a controlled substance in Thailand and works by dilating blood vessels to increase blood flow to the man's member. However, Sildenafil can also damage the optic nerves, causing blindness if taken indiscriminately.

Other unwanted side effects include increased blood pressure, migraines, and an irregular heartbeat which can lead to death.

The country's Food and Drug Administration (FDA) announced this month it is now 'considering' filing cases against the manufacturers of the Viagra coffee.

Ethan Meyer, a customer who tried Gomax Coffee after buying it from the 'Blez Pharmacy' shop on Sukhumvit Road , said: 'I thought the coffee would be good to drink discreetly at breakfast, without my wife seeing what I was doing. I tried the coffee but after a couple of hours, there was no effect, other than a throbbing headache.

'I felt a bit dizzy so went out for a massage, because I thought it would be better to have some people around who could help in case I collapsed.

'That was then the coffee began to have the intended effect. The erection lasted all night and throughout the next day and evening.

'My eyes were a little blurry, but thankfully I could still see. I also felt very thirsty and a little bit short-tempered, but I didn't feel my overall health was in danger.

'I'm relieved that nothing worse happened as I definitely would not have tried the coffee had I known it had been banned in the country.'

Due to the potential harm it poses, Sildenafil is considered unsuitable to use in food and drinks. Selling such products is punishable in Thailand by detention of up to two years, or fines reaching 20,000 THB (around 557 USD).

Officials said that Gomax Coffee is produced by PY Intergroup Col, Ltd., in Nonthaburi province and distributed by Nice Good Deal company in Bangkok.

It is sold in boxes of 10 sachets, which are enough for one hot drink.

The FDA warned that people with liver disease, kidney problems, hypotension, heart failure, or unstable heartbeats should check with doctors before taking Viagra and 'be cautious'.