A man fills a balloon with nitrous oxide to sell to a customer in Ho Chi Minh City. Photo by Bien Thao

It's almost midnight, but at a club in downtown Ho Chi Minh City, people are just beginning to arrive and crowd the place.

Many are already walking unevenly after drinking elsewhere.

After hundreds of them have entered, a balloon feast begins, and the emcee instructs the crowd on how to release the balloons slowly, so that they can inhale nitrous oxide (N 2 O).

He lists various health impacts such as how the laughing gas would make them sober, that it would trigger laughter, which "everyone must know works like a thousand doses of tonic."

His bragging on the microphone is quickly drowned out by uncontrolled laughter from the audience.

The N 2 O-filled balloons are called funky balls and they have become a night life fashion in Vietnamese cities, though experts have warned about addictive effects, even brain damage, from abusing the anesthetic gas.

The recreational use of nitrous oxide was popular in the US and several Western countries several years ago, as young people inhaled or snuffed the odorless gas, sometimes from whipped cream containers, for the feelings of relaxing, euphoria, or visual hallucinations.

A survey by the US Substance Abuse and Mental Health Services Administration cited by media last year showed that more than 12 million people in the country have tried nitrous oxide, also known as whip-its, at least once.

Le Thanh Liem, deputy head of the Drug Crime Department at the Ministry of Public Security, said the game was brought to Vietnam by backpackers and has created a "fever" in HCMC, Hanoi, Hai Phong and Quang Ninh Province.

Liem said funky balls are now a legitimate product but the gas also works like a kind of drug.

"It makes people feel high, lose control of their behavior and easily become addicted," the officer said.

At the "funky ball by night" party in HCMC several mobile phone numbers were handed out in case people want more of the gas later. Home delivery service is available.

A man who claimed to be a provider for HCMC market said he currently has delivery for orders of a box of 580 balloons.

Each box costs VND6.5 million (US$308) and the customers also have to pay a VND1.5 million deposit which will be refunded when the balloons are returned.

A funky ball shop on Nguyen Van Nghi Street in HCMC's Go Vap District sells five balloons at a time for VND40,000 apiece. Purchasers of ten balloons a time can avail of a ten percent discount.

"Please enjoy and spread the word about your experience to your friends," the vendor told an undercover Thanh Nien reporter.

Not fun in the long run

Doctor Le Ngoc Anh from Phu Nhuan District Mental Health Center in HCMC said laughing gas is not all that it is talked up to be by its promoters.

He said doctors in other countries where it used to be a fad have warned about nerve damage that causes loss of sensation, as well as seizures and cardiac issues due to the lack of oxygen supply to the brain.

Vomiting is also a common side effect and inhalers can risk their life when aspirating vomit into their lungs.

Nitrous oxide is often used by dentists as a pain-killer, but in a dental setting, nitrous is mixed with oxygen and delivered through a mask, while inhaling nitrous oxide directly from a canister causes a drop of oxygen flow to the brain, or a part of the body.

If the derivation of adequate oxygen supply continues for more than a few minutes, it can lead to brain damage or even death, doctors said.

Dr. Anh said the game can be fatal to people with asthma or other respiratory conditions, as the gas can stifle their breathing.

It's also dangerous to take the gas with other drugs, like ecstasy, as many young people are doing. The combination can cause confusion, headaches and make one pass out. Doctors say one can die if such effects last for two to three minutes.

Dr. Anh also said that after a long term use, the gas can trigger mental disorders like loss of memory.

A player only identified as K.N. said he frequently suffers a sore throat and has lost his "manly" voice after using the gas for a while.

Now he sounds like a girl, claiming his girlfriend who also inhales nitrous oxide has started to speak with hoarse voice and grown a mustache that she needs to shave every week.

But Dr. Anh said impacts of nitrous oxide on hormones are yet to be confirmed.

She said there is a possibility that the balloons that are being used could have been filled with kinds of gas other than N 2 O to enhance the euphoric feeling, and such combinations could lead to hormonal changes.