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Middlesex-London Health Unit

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Inhalation Analgesia (Nitronox Gas)

Nitronox is a mixture of nitrous oxide gas and oxygen (also known as laughing gas)

The following information will assist you to make an informed decision about the use of inhalation analgesia for pain relief in labour that is in line with your preferences and values. It’s important to learn about the benefits, risks and alternatives before labour begins. The following are population level benefits and risks. In order to make an informed decision, it's important to speak with your healthcare provider to discuss how these may apply to your individual situation.



  • May provide effective pain relief
  • Is self-administered
  • Does not get rid of pain but makes it seem less intense.
  • Is a short acting medication that does not affect your baby or your labour


  • Nausea/vomiting
  • Dizziness
  • Drowsiness
  • You might find it difficult to breathe through a contraction with the mask on
  • Hallucinations (seeing or experiencing something that is not there)
  • Hyperventilation (breathing too fast) or hypoventilation (breathing too slowly)
  • Maternal and fetal hypoxia (low blood oxygen)
  • Loss of consciousness (extremely rarely and usually only if narcotics are also being used)


There are a variety of coping techniques you can use to manage the pain you experience during labour. Comfort measures do not involve the use of medications for pain relief. They allow you to have a better sense of control, can result in a shorter labour with fewer medical interventions. Using comfort measures to avoid unnecessary interventions also supports your birth hormones. This will help you to have a labour that feels less intense and progresses more quickly. It also sets you up for better breastfeeding success. There is also no risk for you or your baby. See our Comfort Measures webpage for more information.


  • The gas needs to be inhaled through a facemask or mouthpiece as soon as a contraction begins.
  • It takes approximately 30 - 60 seconds of inhaling before there is any effect.
  • You will continue holding the mask to your face during the contraction while breathing slowly and deeply in and out. Exhale into the mask to lessen exposure to others in the room.
  • You must hold the mask yourself so that the correct amount of medication is given. Your partner or nurse cannot hold it for you.

For more information, decision aids & tools:

If you have specific questions:

  • Speak with your healthcare provider
Date of creation: February 20, 2015
Last modified on: June 4, 2019


1Middlesex-London Health Unit & London Health Sciences Centre (2014). Birthing at London Health Sciences Centre. Retrieved from
2Klomp, T., Poppel, M. V., Jones, L., Lazet, J., & Di Nisio, M. D. (2012). Inhaled analgesia for pain management in labour. Cochrane Database of Systematic Reviews. Retrieved from;jsessionid=FA44F34A8895A0DAF417CDC27F6F6B0F.f02t03
3Best Start Resource Centre. (2016). Pain Medications in Labour. Retrieved from
4National Collaborating Centre for Women's and Children's Health (UK). (2014). Intrapartum care: Care of healthy women and their babies during childbirth - Chapter 8: Coping with pain in labour-non-epidural. Retrieved from