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Pain Relief - Entonox / Nitrous oxide


Photo source: https://birthinternational.com


Labour and childbirth is usually a painful experience and women vary in their response to it. Some women wish to avoid drugs or other medical interventions, while others are happy to consider all available options. It is a good idea to be aware of all your alternatives and the different methods of pain relief in order to make an informed decision.


The below article looks at entonox as a form of pain relief.

What is Entonox / Nitrous oxide?


Referred to as Entonox, Nitrous oxide, Gas and Air, or Laughing Gas, Entonox is a colourless and odourless gas made up of half oxygen and half nitrous oxide. It is administered to the mother through a facemask or a tube held in the mouth and has a calming effect and takes the edge off labour pain, rather than blocking it out completely.

Entonox should be available wherever you choose to give birth in most hospitals, including in birth centres. Most hospitals pump entonox to the labour wards from a central supply, or if you're in a smaller hospital or a birth centre your midwife may bring you entonox in portable cylinders. Check with your homebirth midwife whether she carries gas and air.

When and how should I use it?


You can have entonox whenever you want in labour. It is administered through a mask or mouthpiece:

  1. Simply bring the mask up to your face or put the mouthpiece between your lips or teeth.

  2. Keep it there as you breathe deeply and evenly. The mask or mouthpiece has a two-way valve that releases the gas and air for you to breathe in and takes away the carbon dioxide you breathe out.

  3. Continue to breathe deeply until you start to feel a little light-headed. Take the mask or mouthpiece away from your face.

  4. Within a few seconds, you will feel perfectly normal again.

It takes only approximately 30 seconds for the gas to build up in your bloodstream and for you to feel the benefits. It is important to breathe from the mask as soon as you feel a contraction beginning. You may need a bit of practice to get the timing right. If you wait until the contraction really hurts, and then start breathing, it will take effect between contractions.


What are the advantages of entonox?

  • Nitrous oxide does not interfere with contractions, nor does it linger in your body or your baby’s.

  • While it doesn’t stop the pain completely, it can take the edge off the pain.

  • You are in direct control of it, even while feeling its effects.

  • It is flexible and quick-acting.

  • It is easy to use.

  • It doesn't stay in your system. As soon as you stop breathing it in, the gas and air in your system is cleared by your lungs and any side effects will stop too.

  • It's safe for your baby.

  • Your baby does not require any extra monitoring.

  • It can be used while in the water if you give labour in a birth pool or in the bath.

What are the disadvantages of entonox?

  • It is only a mild painkiller - for around one-third of women, nitrous oxide offers no pain relief at all.

  • It may take a while to get the timing right so that it's effective at the peak of your contractions.

  • You may feel light-headed or sick and experience nausea and vomiting.

  • It may cause confusion and disorientation

  • It dries out your mouth if used for long periods.

  • Keeping hold of the mask or mouthpiece may stop you from moving around and getting into a comfortable position.

  • For those prone to claustrophobia, you may feel claustrophobic sensations from the facemask

  • If used with painkilling drug pethidine, it may make you feel even more drowsy.

Useful tips for entonox:

  • Confirm with your health carer before you go into labour whether the mouthpiece or mask and breathing tube are new, or if it will be properly cleaned beforehand.

  • If you're having a home birth, ask your midwife if she carries gas and air during your antenatal visits. When she arrives ask her to check that the mouthpiece, valve section and breathing tube are all in working order and that she has enough canisters for your labour.

  • You control the gas delivery so ask your midwife for a demonstration on how to use it for maximum effectiveness. The midwife can increase or decrease the amount of gas as you desire.

  • Sips water in between contractions to keep your mouth moist.

  • You may find it easier to concentrate in the second stage of labour without using entonox. Alternatively, you could have a little gas and air at the beginning of each contraction, but then put the mouthpiece to one side.


Entonox may not be enough to help you cope with contractions. If this is the case using gas and air can be used in conjunction with other pain relief drugs.

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