What it is

GHB comes in two forms — a clear, odourless liquid or a white powder that is usually made into tablets or capsules. It is most commonly used in liquid form, which is sometimes mixed with alcohol.

What it does

GHB was originally manufactured as an anaesthetic so it has a strong sedative effect when taken. It is classed as a depressant because of its sedative effect. More recently GHB has been used as a recreational intoxicant. For many users, GHB is an alcohol replacement.


GHB is highly addictive. Users can become physically- and psychologically-addicted to GHB if used on a regular basis. The risk of overdose is also significant because GHB often comes as a clear or coloured liquid and it can be difficult to judge the potency. 

There is a very fine line between the amount required to reach the 'desired effect' and an overdose. And the same dose can affect different people in different ways. 

GHB withdrawal 

Withdrawal effects may include hallucinations, insomnia, anxiety, tremors, sweating, edginess, chest pains and tightness, muscle and bone aches. These side effects will generally subside after 2–21 days.

Stopping GHB use suddenly might also result in bladder and bowel incontinence and blackouts. These withdrawal symptoms may require medical assistance.

Reducing the harm

The New Zealand Drug Foundation’s message is clear: no drug use is the safest drug use. However, we know there will be occasions when people ignore warnings and use drugs in a dangerous manner. To help keep communities safe, here is some information about proven methods of drug harm reduction.

Because it is difficult to judge the concentration of GHB, there can be a very fine line between the amount required to achieve the desired effect and the amount which leads to overdose and coma.

Extreme care should be taken with GHB. Avoid use if there is any doubt or uncertainty.

GHB should not be combined with other drugs, especially alcohol and other depressants. Combining it with other drugs intensifies its effects and increases risk of respiratory collapse and vomiting. If vomiting or convulsions occur, immediate medical attention must be given and emergency staff must be promptly informed of what the user has taken. See the Drug Foundation’s How to Get Help section (LINK) for more information on managing an overdose or bad reaction to GHB.

The Expert Advisory Committee on Drugs has produced key messages for GHB users:

  • After taking GHB do not drive a vehicle, operate heavy machinery or engage in water-related activities.
  • Do not take GHB when alone, or with strangers. 
  • Do not take drinks from strangers, or leave glasses unattended, because someone might spike your drink.

GHB should be kept in a container that cannot be mistaken for a drinking container or water bottle. People have been known to colour their GHB with blue food colouring (hence the term ‘blue nitro’) to distinguish it from water. It is also recommended that those using GHB write “G" or “GHB" on their hand so that if trouble occurs, others including medical staff will be aware it has been taken.

More information