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Gas (Entonox)

4-minute read

Key facts

  • Gas, also known as nitrous oxide or Entonox, can help with pain relief during labour.
  • You breathe in gas through a mask or mouthpiece during contractions.
  • Gas is safe for you and your baby and does not affect your labour.
  • Side effects of gas include nausea, vomiting and light-headedness, although these pass quickly once you stop using it.
  • You should hold the mask or mouthpiece yourself, so you can stop using it straight away when you don’t need it or if you experience side effects.

What is gas pain relief?

One option for pain relief in labour is nitrous oxide gas mixed with oxygen. It is also called Entonox, laughing gas or just ‘gas’.

You breathe it in through a mouthpiece or mask.

Gas can help with pain relief, and it is safe for you and your baby.

How do I use gas for pain relief during labour?

A mouthpiece or a mask is connected by a tube, to a gas supply that is either in a cylinder or attached to the wall. When you want to use gas, you hold the mouthpiece or mask to your mouth and breathe in deeply. The amount of gas you breathe in depends on how hard and fast you breathe.

You usually use gas only during contractions. Because it takes a while to work, it's best to start breathing before the contraction starts. It helps to have someone with you, timing your contractions, so you know when to use the gas.

You can stop using the gas any time you want. Hold the mask or mouthpiece yourself, so you can stop using it straight away when you don’t need it or if you experience side effects.

Why would I choose to use gas during labour?

There are many reasons you might use gas during labour:

  • It helps relieve pain.
  • It can be used at any stage of labour.
  • It doesn't have effects on your baby.
  • It doesn't stay in your body for very long.
  • You can control the amount of gas you use.
  • You can move and change position between contractions.
  • It can help you breathe rhythmically.

What are the disadvantages of using gas during labour?

There are some disadvantages to using nitrous oxide during labour.

  • It’s only partly effective for some people — it might only dull the pain without decreasing it enough.
  • People with some medical conditions shouldn’t use it.
  • You shouldn’t use nitrous oxide if you are taking medicines, such as pethidine, that make you drowsy.

What are the side effects of nitrous oxide for me and my baby?

Nitrous oxide has no known bad effects on your baby.

Some people experience side effects such as dizziness, light-headedness, nausea or vomiting.

If you breathe in too much gas, you may overdose. This can cause you to become drowsy or briefly unconscious, but you will usually recover quickly once you stop breathing in the gas.

You are unlikely to overdose if you are holding the mouthpiece yourself.

Where can I get more information on using gas in labour?

You can call Pregnancy, Birth and Baby on 1800 882 436, 7am to midnight (AET) to speak to a maternal child health nurse to help you prepare for childbirth, and for advice on natural and medical options for pain relief during labour.

You can ask your doctor or midwife if gas is suitable in your situation. They will be able to answer your questions and show you how to use the mouthpiece.

Speak to a maternal child health nurse

Call Pregnancy, Birth and Baby to speak to a maternal child health nurse on 1800 882 436 or video call. Available 7am to midnight (AET), 7 days a week.

Learn more here about the development and quality assurance of healthdirect content.

Last reviewed: July 2022

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