Lauren, 24, is scrolling through her Instagram profile while she waits at the bar, in a club in a Yorkshire town. The young women in her pictures have long, glossy hair and matte-painted mouths. In one shot they huddle together under a neon sign, the light strobing off their highlighted cheekbones. Underneath most of the photos is written #GNO. “It means Girls’ Night Out but also, for us, G Night Out,” she says. “We came up with it when we first started taking G at uni, and were just loving it and loving life.”

In a corner of the club, Lauren reaches into her bag and plucks out a 30ml, clear plastic spray bottle. It’s the kind you might decant a favourite perfume into, to pack in your carry-on luggage. She points the bottle into her glass of lemonade, pumps twice, swirls it and drinks the mixture in three gulps. Her friend Holli, 23, follows suit. On her phone Lauren sets a timer to count down the next 90 minutes, until the time they’ll take some more. “It takes around 10 minutes to work,” she says, heading back to the bar for a glass of water.

They have just taken G, aka GHB, also known as liquid ecstasy. It can be found in powder form, but more usually an odourless, colourless, slightly salty liquid that prompts a brief, powerful euphoria. When the dosage is wrong, or when it’s mixed with another central nervous system depressant such as alcohol, GHB can put the user into a coma in a matter of minutes, which is why the women aren’t drinking. “I was with two friends who don’t drink alcohol the first time I tried G,” Holli says. “For them, G just made sense – no sugar, no calories and no hangover.”

GHB sits in a risk category all of its own, way above other party drugs. It's incredibly dangerous

GHB’s popularity among young women and clubbers in general marks the third stage of its evolution as a drug: first, it was best known as a potent and dangerous date rape drug, slipped into the drinks of unknowing victims. Then it became popular at chemsex parties. Now it’s increasingly popular among young clubbers all over Europe.

According to data given to the Guardian by this year’s Global Drug Survey, out of 1,000 GHB users, one in four women (and one in six men) have overdosed in the last 12 months alone. “That’s a staggering rate of overdose compared with any other recreational substance,” says Adam Winstock, psychiatrist and founder of the survey. “GHB terrifies me as a specialist,” he adds. “It sits in a risk category all of its own, way above other party drugs. The fact that users fall into unrousable states is incredibly dangerous. They’re not only vulnerable to assault, they might stop breathing altogether.”

“The dose thing is tricky,” Holli admits. “We had to work out exactly how much liquid you get per spray. Two sprays is enough for us, some of our guy mates do three.”

The effects from a single dose usually wear off after an hour or so; the women use the timer to avoid re-dosing too early. “We’ve both ‘gone under’ a few times,” Lauren says – they use this term for when they slip into an unrousable sleep, effectively a coma. “But most people do at some point. Usually after you’ve been on it all night and you’re not paying attention to how much you’re taking. It happened to me at a house party a few months ago. I remember I was on the sofa chatting to someone, then the next thing I’m opening my eyes in another room, there’s a coat over me and it’s light outside. My friends had moved me somewhere quiet and kept checking on me. That’s basically it. You roll the person on to their side and let them sleep.” (Winstock agrees that the recovery position is best for someone who has passed out from GHB and that an ambulance should be called if breathing slows to less than eight breaths a minute.)

Gamma-hydroxybutyrate – or GHB – was first synthesised for use as an anaesthetic in the 1960s and has since been used variously as a treatment for narcolepsy and, in the 1980s, as a fat-burner and muscle-builder. By the early 2000s, word that it could induce euphoria had spread and it began to appear more frequently as “liquid ecstasy”. Unlike many other party drugs, GHB can be made in the UK with the right mix of industrial chemicals, and most dealers can be found online.

Students play ‘G roulette’ – one person gets a double dose, drinks it like a shot, then they’re passed out for the night

There are many problems with GHB, but the most pressing for recreational users is that the difference between euphoria and overdose can be a matter of a single millilitre. “Depending on your body weight, 1ml might be enough to have a good time,” says Peter Sheath, from the drugs charity Addaction. He’s based in Liverpool and has been working for two years with men on the chemsex scene, where drugs (mainly GHB, as well as crystal meth) are used at sex parties to enhance the sexual experience and help revellers feel uninhibited. “But go up to 2ml and you could be in accident and emergency in a coma,” Sheath says.

“Now, imagine trying to be that accurate in the context of a night out. You might have taken other substances, it’s dark and G – which is sold as a drain and alloy wheel cleaner – tends to melt plastics, so any measures you’ve got marked on a pipette [how it’s commonly taken] will be gone by the end of the evening.” (Holli and Lauren’s bottle is double thickness, non-melting plastic.)

The drug has been a class C controlled substance in Britain since 2003. It’s difficult to establish how many users there are in this country; it leaves the system within hours, making it difficult to test for, even in the case of a fatality. Sheath believes it’s more widespread than many realise. “I’ve heard about it being used a lot by the student population in Liverpool. They play ‘G roulette’ – everyone is poured a measure [1ml] but one person gets a double dose. They drink it like a shot, then one person ends up overdosing and they’re passed out for the night.”

At the club, the women are talking animatedly about social mobility issues (Holli is training to be a social worker, Lauren is interning for a charity) and the impact of Brexit on their respective home towns. Other than the odd, brief moment when their faces relax into dopey, wide-eyed smiles, they don’t yet seem particularly intoxicated. Neither has played G roulette, but they have heard of similar “party games” – “It’s just kids trying to get fucked up,” Lauren shrugs. Both she and Holli argue that it’s a “safe” drug that fits into their lifestyles. “It’s not like coke where you’re up for days,” Holli says. “You actually feel refreshed when you’ve woken up from a night on G. I’ve gone for a run the next afternoon after being out until 7am. You can even go to the gym on G,” she says. “My ex-boyfriend did.”

Facebook Twitter Pinterest ‘The dose thing is tricky. Two sprays is enough for us, some of our guy mates do three.’ Photograph: Alamy

This seeming innocuousness, researchers argue, is what makes GHB so dangerous. Harmen Beurmanjer is a leading GHB researcher based at Novadic-Kentron, a drug rehabilitation centre in the Netherlands. He’s been studying GHB there, where use is more widespread and well-documented, for more than a decade. “Maybe they’re feeling a little low on Monday morning, they take some G and suddenly they feel fine,” Beurmanjer says. “When we first started treating GHB addiction, we were finding that the majority of people who were using it were in their 20s and very severely addicted. This is not like any other drug, where most addicts are older and have become addicted because of years of abuse. These young people were hooked within weeks.” Winstock agrees: “I’d say that people will start to experience dependence within two to three weeks of regular use. This is staggeringly quick.”

Steven, 29, stopped taking GHB a few years ago. “At first it seemed a nice alternative to alcohol,” he says. “I was going out a lot at the time and finding it difficult to keep up with my friends’ drinking – my hangovers would last for days. So I switched to G. And it was good until it wasn’t. After a few months of this weekend habit, I found I was craving it more and more.” He was amazed by how quickly he got hooked. “It went from something casual to a proper craving. I’d wake up on a Wednesday thinking, damn, two more days until I can do G again. And then I started to get anxious. I knew then that I had to stop. I distanced myself from those friends for a while – but I know that now, three years on, some of them do it every day. I’m just so glad it never came to that for me.”

Some argue that GHB is harder to withdraw from than heroin. “It starts with shaking, then anxiety, paranoia and finally complete delirium,” Beurmanjer says. “You cannot withdraw alone; you need medical attention. And withdrawal symptoms happen very quickly – a person will have entered delirium within six hours.”

According to research published by the European College of Neuropsychopharmacology (ECNP) last month, abusing GHB can damage long-term memory, working memory and cognitive function. “When you slip into a GHB coma you get hypoxia – basically, less oxygen to the brain,” Beurmanjer says. “But we can’t talk about the long-term impact because we’ve only really studied it for the past 10 years.”

Paddy Bloor died, aged 21, after taking GHB. ‘He wasn’t a regular user,’ his father says. ‘He thought he was in control’

Beurmanjer argues that the rise in popularity is because GHB is cheap – Holli and Lauren pay around 30p per dose – users don’t immediately see the downsides and it is, effectively, a dose of liquid confidence. “I have many female patients who started because of that,” he says. “It won’t cure your anxiety, it’s just that you don’t feel it when you’re on GHB. And they become addicted so fast because they feel so great. But when they quit, they say, ‘I feel like I’ve lost part of my personality. With GHB I know how to talk to people, I can be my best self – without GHB, I’m afraid of everything.’”

On a neurological level, GHB works in a similar way to depressants such as alcohol and medicines from the benzodiazepine group, such as diazepam and lorazepam. Ironically, although in the short-term it makes users feel invincible, in the longer term it leads to an increase in anxiety and depression. “GHB takes over your emotional regulation system. So when you come off it, you realise you can’t cope with your emotions properly,” Beurmanjer says. Addicts are given therapy and pharmaceutical-grade GHB in decreasing doses to wean them off slowly and avoid physical withdrawal.

Even short-term, sporadic use can be dangerous. Graham Bloor’s son Paddy died in March this year. He was a 21-year-old biochemistry student at Sheffield University: clever and extroverted, with a buzzing social life. “He had a hedonistic view of the world,” says Bloor, a retired anaesthetist. “It was arrogant, really. He thought he knew about drugs, that he was in control. He was going to party until he was about 25, then ‘grow up’. That was his view.”

Facebook Twitter Pinterest Paddy Bloor, who died in March. Photograph: courtesy of Graham Bloor

In the early hours of 8 March, his parents got a call to say Paddy was in a coma. He’d been at a chemsex party. “He wasn’t a regular user of GHB, we know because we’ve accessed his social media,” Bloor says. “He arrived at a party at 4am. We don’t know how much GHB he had, but he passed out and the guys who were there left him to sleep it off. It’s hard to work out an exact timeline but at some point they must have thought he was so unrousable that he needed medical attention and they called an ambulance.”

The ambulance arrived at 5.45, by which point Paddy had already suffered a cardiac arrest. The paramedics were able to restart his heart, but his brain had been starved of oxygen for too long and he never recovered. He died in hospital two days later. He was the eldest of triplets. In the back of their minds, as they took turns keeping vigil over Paddy and whispering quiet words of encouragement, his brothers and parents clung to the hope that he would pull through. His death stunned them.

“The problem is, if you leave the person to sleep off their so-called ‘G hole’, then you don’t know what state they’re in,” Bloor says. “The guys at the party said he had been snoring – my guess is that he was going into respiratory failure. But they wouldn’t have recognised that. What would you do if your partner was snoring? You’d just move rooms.”

He wants coroners to test routinely for GHB – because it has a short half-life, it has often left the body. But a urine sample can reveal it and if GHB use is suspected, testing may be requested. “Our local coroner was quite dismissive of the idea,” Bloor says quietly. He fought for the test to be done because a friend of Paddy’s had recently overdosed on GHB, and a vial of clear liquid, thought by the police to be either GHB or ketamine, had been found in Paddy’s pocket. “The test showed he died of GHB toxicity, which caused him to go into cardiac arrest, something we found out only because we pushed for the test.”

More than 400 people attended Paddy’s funeral. “His friends came from all over the UK. It was terribly grand and terribly sad.” Bloor is keen to warn people of the dangers: “I think we need to educate people. To let them know what G is, and what it can do.” He argues that GHB fatalities are a much bigger problem than anyone currently understands. “Until we start to test for it routinely, we won’t know. But when, or if, it goes mainstream, the authorities will be very embarrassed that they never took it seriously.”

It’s killing a lot of people. They say it's a heart attack, but these are young guys – hearts don’t just stop

Researchers and activists within the LGBT+ community say that over the past few years, G-related deaths have reached epidemic proportions. “I can’t help but liken it to the Aids crisis,” says David Stuart, a London-based gay rights activist and campaigner. “It isn’t killing as many people, but it’s had a devastating effect on the community since it took over from ecstasy as the drug of choice.” He describes the transformation of “ecstasy dancefloors”, filled with happy, loved-up people, “into places where people were fitting, collapsing and falling unconscious”.

“I hear of two or three deaths every month just within our small community. When you read the comments about them on Facebook, you find that they were regular users of G. It’s everywhere and it’s killing a lot of people – including, reportedly, George Michael. But because it disappears from urine and blood so quickly, it has flown under the radar of the authorities. They just say the person suffered a heart attack, but these are young guys – their hearts don’t just stop.”

There have been few studies into GHB deaths. One, conducted by Imperial College London, focused exclusively on the capital and found that there was a year-on-year rise in the number of deaths between 2011 and 2015, and that towards the end of that period, GHB deaths rose by 119% in a single year. At one point, one man was dying in London of GHB-related causes every 12 days. According to the ECNP, GHB overdose is the third most common drug-related cause for emergency medical treatment in Europe, behind heroin and cocaine. As Beurmanjer says: “My colleagues and I have spoken to researchers in Germany and Belgium, where they have a big problem with it. And I’ve received calls from [hospitals and research facilities in] Copenhagen, Switzerland, Norway... It’s everywhere. I wouldn’t say it’s as big as cocaine, but it has the potential to be because it can be highly addictive.”

***

By now it is 1am and the club is busy. “Young crowd,” Holli says, though everyone seems about the same age as she is. The dancefloor is so busy that they weave and squeeze between groups to find a space to dance at the back next to a bass-heavy speaker. In contrast, the bar area is almost deserted. A handful of staff stand back looking bored; the odd one or two clubbers who do approach the bar generally leave clutching a bottle of water. “I’m not sure what everyone here is on, some will be G,” Lauren says. “But you never know. Look out for the ones who can’t dance in time to the music,” she adds, smiling.

“I can feel it working,” she says. “You don’t think about anything negative, or you see negative things in a new, positive light. It’s like living the Instagram version of your life, where you look amazing. And you feel as confident and happy as you seem.”

As the night progresses, Holli talks to a guy – as she dances, he traces shapes on her back with his fingertips. He, too, is on G. She shivers and giggles. They move together; they kiss and laugh, and at one point discuss leaving together, but decide to swap numbers and meet another time. Lauren and Holli have made a pact not to leave a club with strangers if they have taken G. “You learn as you go. The sex is amazing. But then it’s a bit dangerous, isn’t it? Because when you’re off it, you’re like, ‘Should I have done that? Should I have said that?’” Holli says.

By 4am both women have re-dosed twice and are ready to go again, before heading to a friend’s house to continue the party. Since graduating, they say real life has been a bumpy ride. They talk a lot about “pressure” but, they explain, not to be “successful”. “It’s more like, you’re meant to feel good and be happy, even without success. But life’s shit sometimes, isn’t it?” Holli says.

“Not when you’re on G,” replies Lauren.

Some names have been changed.

The Global Drug Survey 2019 is underway. To share your experiences, visit globaldrugsurvey.com

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