Labour pain relief: Entonox (gas and air)

Here’s what you need to know about Entonox - otherwise known as gas and air

What is Entonox?

Entonox is a colourless, odourless gas usually made up of half nitrous oxide and half oxygen. Some hospitals add other substances to make it more effective but this might make women more sleepy (OAA, 2019)

Why is Entonox used in labour?

Nearly 80% of women use Entonox in labour because many find it to be the best option from a range of inhaled pain killers (CQC, 2019). Entonox has no negative effect on contractions, and you and your baby quickly get rid of it from your bodies (Jones et al, 2012).

How is Entonox used in labour?

It’s self-administered so you breathe in Entonox through a mouthpiece or mask that you grab when you need it. Your caregiver will show you how to breathe in and out properly through the mouthpiece during a contraction. It takes 15 to 20 seconds to work effectively (NHS, 2017).

How effective is Entonox?

Entonox is said to be of ‘moderate’ help with pain and is, surprisingly, more effective at easing pain than opioids (Jones et al, 2012; OAA, 2016; OAA, 2019)

Can everyone use Entonox?

Some women say Entonox makes them feel sick so they might want to avoid it.

What are women’s experiences of Entonox?

Women who use it like being able to control it themselves (NHS, 2017).

Does Entonox have any side effects?

There are no significant side effects for women or babies when used appropriately – in other words, during contractions only (NHS, 2017; Jones et al, 2012). Slight side effects some women experience are feeling dizzy or being sick and they often say they have a dry mouth (Jones et al, 2012; OAA, 2016; Lowth, 2017; NHS, 2017).

Does Entonox affect labour or breastfeeding?

It has no impact on how labour progresses, and there is no suggestion of any impact on breastfeeding (OAA, 2016)

Does Entonox have any long-term effects?

None.

How long do the effects of Entonox last?

You can stop taking it at any point if you choose. The effects of Entonox wear off in minutes (OAA, 2019).

Where and when can I use Entonox during labour?

You can have Entonox wherever you plan to give birth. If you’re planning a home birth, the midwife will bring Entonox with them. You can use it at any time in labour (OAA, 2019).

Can my partner help with Entonox?

Your partner can help by holding the mouthpiece between contractions, while you’re not using it, and then offering it back to you.  This is particularly important if you’re in a bath or birth pool as you don’t want the mouthpiece to slip into the water.

Can I use Entonox with other types of pain relief?

You can use Entonox at the same time as TENS, water, pethidine/diamorphine or self-help measures (e.g. hypnobirthing). 

Will I need any extra procedures with Entonox?

There is no need for extra monitoring or any other additional procedures with Entonox (OAA, 2016).

Are there any other considerations with Entonox?

When discussing options for working with the pain of labour, your midwife might mention the environmental impact of Entonox. This is not to discourage you from using it but because some women might make an informed decision not to. Entonox is a greenhouse gas that accounts for over 2% of the NHS carbon footprint, and about a third of that is used by women in labour (Sulbaek et al, 2012; Sustainable Development Unit, 2013).  

Other pain relief options also have environmental impacts but Entonox is the first one that has been highlighted (Sustainable Development Unit, 2013). NHS Trusts will also be working to address the hospital’s environmental impact in other ways, such as lower temperatures, improved recycling, and transport (Sustainable Development Unit, 2013).

This page was last reviewed in August 2019.

Further information

Our support line offers practical and emotional support with feeding your baby and general enquiries for parents, members and volunteers: 0300 330 0700.

We also offer antenatal courses which are a great way to find out more about pregnancy and life with a new baby.

Research from the Royal College of Obstetricians and Gynaecologists (RCOG) about the use of water as pain relief in labour.

CQC. (2019) 2018 survey of women’s experiences of maternity care. Available at: https://www.cqc.org.uk/sites/default/files/20190424_mat18_statisticalre… [Accessed 18th August 2019]

Jones L, Othman M, Dowswell T, Alfirevic Z, Gates S, Newburn M, Jordan S, Lavender T, Neilson JP. (2012) Pain management for women in labour: an overview of systematic reviews. Cochrane Database of Systematic Reviews. (3):CD009234. Available at: https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD009234.pub2… [Accessed 19th July 2019]

Lowth M. (2017) Pain relief in labour. Available at: https://patient.info/pregnancy/labour-childbirth/pain-relief-in-labour [Accessed 19th July 2019]

NHS. (2017) Pain relief in labour. Available at: https://www.nhs.uk/conditions/pregnancy-and-baby/pain-relief-labour/ [Accessed 16th July 2019]

OAA. (2016) Pain relief in labour: how do the options compare. Available at:  https://www.labourpains.com/assets/_managed/cms/files/InfoforMothers/Pa… [Accessed 5th July 2019]

OAA. (2019) FAQs Pain relief. Available at: https://www.labourpains.com/FAQ_Pain_Relief [Accessed 5th July 2019]

Sulbaek Andersen MP, Nielsen OJ, Wallington TJ, Karpichev B, Sander SP. (2012) Medical intelligence article: assessing the impact on global climate from general anesthetic gases. Anesth Analg. 114(5):1081-5. Available at:https://www.ncbi.nlm.nih.gov/pubmed/22492189 [Accessed 4th October 2019]

Sustainable Development Unit. (2013) Carbon footprint from anaesthetic gas use. Available at: https://www.sduhealth.org.uk/areas-of-focus/carbon-hotspots/anaesthetic… [Accessed 4th October 2019]
 

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