Nitrous oxide therapy factsheet


Nitrous oxide is a gas that can be used to help children with small scans or procedures that might be stressful or painful. It is also known as happy or laughing gas.

Nitrous oxide therapy is used for things like:

  • stitching a wound closed
  • cleaning and dressing a wound
  • changing feeding tubes
  • scans like a micturating cystourethrogram (MCUG), where your child needs to be relaxed enough to do a wee in front of people.

Preparing for the treatment

You will need to talk to your child’s treatment team about nitrous oxide therapy before the procedure or scan. Nitrous oxide can only be used in some kinds of scans and procedures. It is not suitable for every child.

The doctor will need to check that:

  • nitrous oxide is appropriate for the procedure
  • your child is well and can breathe without issues
  • your child can stop eating and drinking before the procedure to lower the risk of vomiting.

Your child’s doctor will speak to you about all options for keeping your child calm and as pain-free as possible.

During the treatment

Nitrous oxide gas is given a few minutes before the procedure or scan starts and will continue until it is finished.

A mixture of nitrous oxide and oxygen gas will flow through to a face mask or mouthpiece. Your child’s doctor or nurse will help secure the mask around your child’s mouth and nose before telling them to start breathing deeply.

Your child will feel sleepy and relaxed as they breathe the gas. The gas should not make your child fall asleep.

After the treatment

The gas will continue to flow until the procedure or scan is finished. Your child’s treating team will turn off the nitrous oxide but continue giving oxygen through the mask. This is to help clear out any remaining nitrous oxide from the lungs.

Once the oxygen starts to flow, your child will become more alert and awake. They should be able to return to normal activities immediately, including eating and drinking.

Some children will not remember anything about the procedure after having the nitrous oxide gas.


Side effects of nitrous oxide therapy

Nitrous oxide therapy is safe when given by a trained health professional. There are no long-term side effects when used appropriately during scans or procedures.

Short-term side effects can happen during and after nitrous oxide therapy. 

Side effects can include: 

  • nausea and vomiting
  • headaches
  • feeling dizzy
  • feeling weak.

These side effects should stop soon after the gas is stopped.

The doctors and nurses can treat the side effects and help your child feel comfortable.

Supporting your child during nitrous oxide therapy

Nitrous oxide gas will usually make your child feel relaxed and sleepy. Some children might feel funny and silly, while others might feel sick.

Some children do not like having to wear a mask or mouthpiece. They may start feeling distressed and angry and might try to take the mouthpiece or facemask off.

Parents and carers are encouraged to stay with their children to help them feel safe and supported.

Speak to your child’s treatment team about different strategies that can be used and whether they can be used during your child’s scan or procedure. 

Strategies can include:

  • telling stories and singing songs
  • watching a movie or TV show on your phone
  • playing with an app
  • playing with a favourite toy
  • playing with the mask or mouthpiece and trying it on before the procedure starts.
Last updated Friday 19th January 2024


This factsheet is provided for general information only. It does not constitute health advice and should not be used to diagnose or treat any health condition.

Please consult with your doctor or other health professional to make sure this information is right for you and/or your child.

The Sydney Children’s Hospitals Network does not accept responsibility for inaccuracies or omissions, the interpretation of the information, or for success or appropriateness of any treatment described in the factsheet.

© Sydney Children’s Hospitals Network 2024

This factsheet was produced with support from John Hunter Children's Hospital.