Dublin, 3am. It’s a Sunday morning in a Dublin apartment. “It’s G o’clock,” cries the host. Six naked men line up to take a carefully measured dose of the drug known as G.

Get the measure wrong and you can become comatose; in the worst case scenario, you can die. A designated responsible person ticks their name off a chart so that they don’t take the next dose too soon, and they down a shot. After a while, sex resumes.

G – short for GBL – is made from common household chemicals. It’s also a party drug which increases libido. Along with the drugs crystal meth, GBH and mephadrone, it has become common in sex parties.

In November last year, the British Medical Journal warned the rise of "chemsex" in the UK means it is no longer an alleged media scare story, but a public health priority. Chemsex typically involves use of illegal psychoactive substances, with multiple partners having sex. In an editorial, the authors warned: "Many barriers exist to chemsex drug users accessing services, including the shame and stigma often associated with drug use and ignorance of available drug services."

Although London is the epicentre of the “chemsex” scene, it is on the rise in Dublin, and for similar reasons.

Adam Shanley, director of Gay Switchboard Ireland, says people may engage in chemsex because of problems with intimacy and relationships, as well as wider social pressures such as sexual health stigma, gym-fit body expectations and turning online chats into genuine relationships.

“If you’ve grown up hearing how gay people are inferior and less, it’s possible that you enter adulthood repressing who you are and guarding against intimacy.

“Relationships can and often do start online, but it’s also easy to organise hook-ups on apps like Grindr, your directory of local gays.

“While chemsex is still relatively rare in Dublin, these potent drugs can remove inhibitions, increase libido and help erase those feelings of shame.”

Crystal meth, G and mephadrone are highly addictive drugs. G is cheap and easily available and can be particularly dangerous because overdoses can induce coma or death and it cannot be taken with alcohol. Users are often young and affluent men with disposable income, who don’t consider themselves addicts.

One man who started taking it on the party scene now takes daily hits. With inhibitions lowered, unprotected sex increases; add needles to the mix and it’s a recipe for higher rates of HIV and Hepatitis C.

On gay dating apps such as Scruff and Grindr, we know what other men mean when they say they are “chem friendly”, though “not into chems” is far, far more common on profiles.

Shanley says there are plenty of people on the Dublin gay scene who take G, don’t become addicted or engage in unsafe sex practices, or go to one or two chemsex parties and don’t return.

“My concern lies with those who do end up with a dependency.”

Dr Paddy Mallon is a HIV researcher at UCD. “Over the past three to five years, my colleagues in London report how gay men meet is changing. The gay bar is in decline. People meet through social media and, instead of using drugs for clubbing, they’re using them to facilitate arousal. Sex is becoming less inhibited and group sex is more common, as is condomless sex.”

This isn’t a “gay problem”, says Mallon, and chemsex is just one facet of a much wider sexual health crisis. HIV is on the rise. The HSE reported 75 new cases of HIV in the first three months of 2015 and 128 in the same period this year, a 75 per cent rise.

Figures from 2014 show that about half of new diagnoses are of men who have sex with men (MSM), with 33 per cent heterosexual and smaller figures for IV drug users (7.2 per cent), mother-to-child transmission (0.2 per cent) and unknown (11 per cent). Syphilis and other STIs are on the march too; Dublin and the east coast are the epicentre and 80 per cent of new syphilis infections are among MSM.

About 40 per cent of MSM have never taken a HIV or sexually transmitted infection test, according to the results of a recent internet survey of 3,000 MSM.

Those least likely to take a HIV test are more likely to be young, not identify as gay, are closeted and have low levels of education.

“Data shows that condomless sex is increasing across the board, including among heterosexual people,” says Mallon. “But we don’t have enough data because sexual health services in Ireland are woefully under-resourced. And the message about safe sex is not getting through.”

Schools remain free to teach whatever they want about sex and sexuality.

US President Barack Obama recently withdrew all federal funding for abstinence programmes. Here, publicly funded schools using these models remain under no obligation to share any information about what they are teaching.

Meanwhile, some schools continue to either ignore homosexuality and the gay children in their class, or they issue a bland statement that “homophobia is wrong” while either openly or tacitly supporting religious doctrines that gay people should abstain from sex.

“Sex education is still too heavily focused on the biological aspects,” says Mallon.

“We need to discuss health aspects, and we need to do it, in age-appropriate ways, at a much younger stage.

“We don’t want HIV stigmatised, but young people need to know that while HIV is treatable, it is a chronic disease and, when not diagnosed on time, still leads to Aids deaths. Nobody is happy to have HIV.”

Mallon and Shanley both say that addiction services, under huge pressure with IV drug use among heroin and cocaine users, have not been able to get on top of it.

“Our services tend to be opiate based and not equipped to deal with this problem, should it become bigger,” says Shanley.

Shanley knows this issue risks stigmatising gay people. “But in London, they swept it under the carpet and it got out of control. We can get ahead of it.”

Nick’s story:

Nick* has been involved in Dublin’s chemsex scene for about two years. Before that, he often had sex while sniffing poppers (amyl nitrate) or on ecstasy or cocaine. He says that most men at chemsex parties are taking drugs, with G the most common but cocaine, E and cannabis are used too.

“It creates a relaxed, euphoric feeling, removing inhibitions about your body, or about your sexuality. It increases horniness. G and crystal can be addictive and I’ve had issues with G addiction, though I’ve dealt with them now and feel able to just use it at weekends.”

At the parties, Nick sometimes has sex with one or two men and sometimes with eight or nine. “Condoms are not used a lot of the time, and drugs tend to stop guys worrying about STIs. I’ve had to get PEP [HIV post-exposure prophylaxis] after possibly exposing myself at a party. But I get tested regularly and am HIV negative.”

The parties can be lonely and disconnected, he says. “I mostly find them to be fun and a good release, but they can be frustrating when some or most of the guys are either too high to have sex, or too distracted by their phones, trying to arrange other, hopefully more attractive guys to come to the party.”

*Name has been changed

This article was amended on June 28th, 2016. The figure of 17 per cent was amended to the correct figure of 7.2 per cent.