Samantha is the reason convenience stores stock an obscure baking item behind the counter next to the condoms and cigarettes. Also known as bulbs and whippets, "nangs" deliver the laughing gas dentists and doctors use, producing 15 to 20-second bursts of euphoria. Although they can cause nerve damage and in rare cases heart attacks, nangs are readily available in Sydney as suppliers exploit a legal grey area. Australians have long dabbled in nitrous as a fringe party drug but have recently upped their use. The Global Drug Survey shows local use rose 50 per cent in the past six years. Half of the ecstasy and psychostimulant users surveyed by the National Drug and Alcohol Research Centre had taken nitrous in the last year. Max*, 40, is one of many users who do nangs to intensify other drugs such as MDMA. "It just takes you into the stratosphere for a minute then brings you back," he says. "It's like the icing on the cake." The ease of access within Sydney's inner suburbs has helped the off-beat industry's growth.

One convenience store belonging to a major chain sells dozens of eight-packs on a special shelf near the register, beneath a piece of masking tape that says: "Do Not Scan." Down the road, another store sells – from under the counter – a box of 360 for $279. Some stores have cottoned on to the bizarre popularity of cream bulbs and have curbed sales. But users are increasingly turning online for cheap deals. One Australian website devoted to the product sells batches of up to 4000. On eBay, in threads such as "Which whipped cream charger is right for you?", customers discuss the merits of Chinese Mr Creamy chargers and Czech Republic Kayser cylinders. Fairfax Media revealed this week an online Melbourne business was making late-night deliveries. The company responded on Facebook that customers misusing the product would be blacklisted. "Lol," several people replied. Knowingly or recklessly supplying nitrous oxide as a party drug has been illegal in NSW since 2013. But what amounts to reckless supply? "There is a significant degree of ambiguity," says product risk specialist Madeleine Kearney, who calls the current laws "unsatisfactory". Nitrous is a "low-risk recreational drug", says Nadine Ezard, a clinical director at St Vincent's Hospital. "The main problem is you can get permanent nerve damage if you use it at a really high dose," Dr Ezard says. In extreme cases, users may might develop an addiction, suffer a heart attack or overdose.

But regular users are unconcerned. Mathilda*, 27, has a headache after doing more than 20 in a night but says nangs are an easy drug to quit. "It doesn't build up like alcohol and leave you wasted and struggling," she says. Samantha, who does up to 40 in a session, says: "If you abuse anything it's dangerous". "I guess the biggest thing from nangs though is the risk of hypoxia – the brain not getting enough oxygen. But I couldn't imagine getting to that point." *Not their real names Long term risks of nitrous oxide abuse:

Peripheral nerve damage

Memory loss

Psychological dependence

Weakened immune system

Heart attack (Source: Australian Drug Foundation)