GHB, GBL, and not dying

GHB and GBL are depressants that, at the right doses, cause euphoria, increase your libido, and lower your inhibitions. They’re usually found as a clear liquid with a bitter aftertaste, but have also been found as a white powder or a bright blue liquid.

What’s the difference between GHB and GBL?

GBL is a prodrug of GHB, meaning that your body will turn GBL into GHB. There’s only a couple of differences between GBL and GHB, but they’re super important.

GBL is far more potent than GHB

A standard dose of GHB in liquid form is 1.5 – 2ml, or 1.5 – 2g of solid. A standard dose of GBL is between 0.9ml and 1.5ml in liquid form, or 0.9-1.5g in solid form. A high dose of GBL is >3g, and a high dose of GHB is >4g. GBL feels far more potent though, so you need far less of it to feel the effect.

Doses above 2ml of liquid or 2g of solid GBL can result in heavy sleep, where people can choke on their own vomit and die if they’re not placed in the recovery position. Doses above 10g of solid or 10ml of liquid GHB have been associated with death.

If you don’t know the exact concentration of your GHB or GBL, you don’t really know what your dose is. ALWAYS presume it’s stronger than you think.

GBL comes on faster than GHB and doesn’t last as long

GBL has an onset time of between 5 minutes and half an hour, and lasts for about 1-2 hours. GHB has an onset time of 10 minutes and half an hour, and lasts for about 1.5-2.5 hours. Both have an after-effect period of between 2 and 4 hours.

Be precise with your G and you’ll be all g

Fuck around and find out, by all means. But if you fuck around with GBL and GHB then you might find out what it’s like to die.
There’s half a ml or half a gram’s difference between a good time and passing out in your own vomit or having a helicopter ride that you won’t remember while some poor bastard tries to keep you alive.

Use proper measuring devices

Use a 0.5 or 1ml syringe or a clean set of scales to measure your dose. GHB and GBL tend to erode plastic in liquid form, so make sure the syringe you use is new as the numbers on the side of the barrel will get worn away over time.
If you don’t have either of these, you can use kitchen measuring spoons. ¼ of a teaspoon is approximately 1.25ml/1.25g, so you’ll want to start with about half of that.

Shake the bottle

GHB and GBL are heavier than the liquid they’re in, and will settle to the bottom of the bottle. This makes measuring doses unreliable as the liquid at the bottom will be stronger than at the top. Shaking the bottle will distribute the GHB or GBL more evenly throughout the liquid and make dosing more accurate.

Reduce subsequent doses

GHB and GBL have a cumulative effect so if you’re having more than one dose over the course of an evening, reduce the dose each time.


GHB and GBL dissolve plastic and rubber so keep any leftover liquid in a glass container. Also label the container and dye the liquid with food colouring so it doesn’t get mistaken for water and drunk accidentally.

G and GCs

Having a ‘sober driver’ is a good idea when you’re taking GHB or GBL. GHB and GBL are disinhibitors that amp your libido up. It’s also super easy to misjudge a dose, take too much, and black out. Your sober driver can remind you to use condoms and lube if things go well, or remind others that passed out people can’t give consent if things go badly.

Dangerous interactions

In general, GHB and GBL do not combine well with any other substances. We’ve listed some known interactions below, but this list is by no means exhaustive.


It’s generally a risky idea to combine drugs with prescription medication. GHB and GBL are a particularly bad combination with benzos, barbituates, gabapentinoids, thienodiazepines, and opioids like codeine or tramadol.

Don’t combine one downer with another – this suppresses your breathing and in some cases you can just stop breathing completely. Funnily enough, if you don’t breathe, you die. (I know, we too were shocked at this revelation)

The combination of alcohol with GHB/GBL is particularly risky and can result in death, but it’s also recommended to avoid the following:

  • Ketamine
  • DXM
  • PCP
  • MXE
  • Nitrous
  • Alcohol. Yes, we know we’ve mentioned it twice, but it’s enough of a high risk to warrant a double mention. The likelihood of you dying if you mix GBL or GHB and alcohol is particularly high, and we’d much prefer it if you didn’t.


Stimulants that have harmful reactions with GHB and GBL are

  • Cocaine
  • MDMA
  • Amphetamines

These will increase your breathing rate, which will make it hard to feel the effects of the GBL or GHB. This might make you want to take a larger dose.
With cocaine and amphetamines, the stimulant will wear off first, leaving a dangerous level of GHB or GBL in your system, which can cause respiratory arrest. If you keep bumping with cocaine you can wind up with a toxic amount of it in your system when the GHB or GBL wears off first.

With MDMA the GBL or GHB can overwhelm the effects of the MDMA on the comedown, causing breathing difficulties.

What to watch out for

As mentioned previously, GHB and GBL can make you pass out very quickly very easily. Other things to keep an eye out for are:

  • Clumsiness/loss of motor control
  • Dizziness or headaches
  • Chills
  • Nausea
  • Slow heart rate
  • Diarrhea and/or difficulty with urinating

Today’s message is short and simple – test your GHB.

We are aware that GHB (Gamma Hydroxybutyrate) is used recreationally at events, even though it’s not often brought to KnowYourStuffNZ for testing. It’s one of the substances that people think doesn’t need testing because it comes in an easily recognisable format. However, all of the samples brought to us as GHB this summer have turned out to be GBL (gamma-Butyrolactone).

GBL is chemically very similar to GHB and converts to GHB quickly once it enters the body. However it’s also two to three times stronger, making the amount required to overdose much lower. The amount that will cause an overdose is also bodyweight dependent, which means taking a GHB-sized dose of GBL can easily lead to overdose and death – especially for smaller people. Adding other drugs increases the risk. Alcohol is especially dangerous to combine with GHB or GBL.

It’s important to know whether you have GHB or GBL before ingesting – please test it first.  If you done have access to KnowYourStuffNZ’s testing service, test kits can be purchased here. Avoid combining it with alcohol, other depressants, stimulants, or dissociatives. As ever, know what you are taking and research the risks.

KnowYourStuffNZ is a not-for-profit social enterprise funded entirely by donations from the community. If you value our work, please donate.

Know Your Stuff-29

More drugs do not mean more fun

There are still plenty of festivals left before the end of the season and KnowYourStuffNZ would like to remind everyone that you do not need to take all the drugs all at once. In fact, you’re much less likely to die if you don’t.

In New Zealand, the vast majority of deaths associated with illicit drugs are found to have involved more than one substance. The most common factor in these deaths is alcohol – many people don’t see alcohol as a real drug, but it’s objectively one of the more harmful, and it’s a bad idea to mix it with many other substances.

In particular the combination of alcohol and GHB is extremely dangerous as they act on the same receptors in the brain. Together they slow your breathing. If you take too much, you stop breathing and die. This summer, several drug related hospitalisations we are aware of have been due to this combination.

TripSit’s combination chart indicates that alcohol is unsafe or dangerous when taken with many of the other drugs we most commonly see at festivals – MDMA, ketamine, cocaine, and cathinones (such as methylone and n-ethylpentylone).

Stimulants are the other major group of ‘festival drugs’ that shouldn’t be used with other things – and particularly not with other stimulants. They increase your heart rate, blood pressure, and temperature, and put a lot of strain on your systems. Adding more stimulants can greatly increase the risks. Amphetamines, MDMA, cocaine, and cathinones (“bath salts”) are all stimulants. And let’s not forget caffeine, which can be dangerous in very high doses or in combination with other stimulants.

Apart from the immediate stresses on the body, stimulants also tend to reduce appetite and prevent sleep. Mixing drugs and then not taking care of basic bodily needs is one of the major factors in drug related problems we see at events.

Put simply, combining drugs is an expensive and often pointless way to risk your life. You can’t enjoy a festival if you are unconscious or have been rushed to hospital.

We strongly advise against combining drugs. To reduce risk of harm, we suggest the following:

  • only one thing at a time
  • in between sessions: Rest, Eat, Rehydrate.
  • stay alive!
KnowYourStuffNZ is a not-for-profit social enterprise funded entirely by donations from the community. If you value our work, please donate.

tripsit interaction guide