A helium and oxygen gas mixture to ease breathing through narrowed airways
Heliox
A mixture of helium and oxygen breathed in to make it easier to move air through narrowed airways.
What is Heliox?
Heliox is a specialist medical gas made of helium mixed with oxygen, breathed in to help air move more easily through narrowed or partly blocked airways. Because helium is much lighter than the nitrogen in normal air, the mixture flows more smoothly, which can ease the work of breathing in certain emergencies while other treatments take effect. It is used by specialist teams, not as a regular medicine. An important point is that enough oxygen must always be included, and a harmless, temporary effect is that helium makes the voice sound high-pitched. It supports breathing but does not treat the underlying cause.
Education and reference only. This is a plain-language guide to Heliox — it deliberately contains no doses. Doses depend on the person, the brand and the reason for treatment, and belong with your prescriber. Always check the BNF, the product labelling (SmPC) and follow medical advice.
What it is
Heliox is a breathing gas made by mixing helium with oxygen. It is used in hospital, often in emergency or intensive-care settings, to help people whose airways are narrowed, for example by severe airway swelling or a tight obstruction, breathe more easily. The helium makes the gas lighter than ordinary air, so it flows through tight passages with less turbulence and effort. It is a supportive treatment that buys time and reduces the work of breathing while the underlying problem is being treated. It is given and supervised by specialist staff.
How it works
Normal air is mostly nitrogen, which is relatively heavy, so when airways are narrowed the air becomes turbulent and hard to push through, increasing the effort of breathing. Helium is much lighter than nitrogen, so a helium-oxygen mixture flows more smoothly and with less resistance through narrowed passages, making each breath easier and helping oxygen and inhaled medicines reach the lungs. Because the benefit comes from helium's lightness, the mixture has to contain a large proportion of helium, which means the amount of oxygen it can carry is limited, so the team always makes sure enough oxygen is given. It supports breathing rather than fixing the cause of the narrowing.
Company & origin
Originated / developed by: Medical gas suppliers.
A specialist medical gas used in the UK in some emergencies to help people breathe when their airways are narrowed.
Practical use
How to take Heliox
General, dose-free guidance — always follow your prescriber's and the leaflet's specific instructions.
- It is given in hospital by specialist staff, breathed in through a mask or breathing circuit.
- It is used as a supportive treatment in selected emergencies while the cause of the airway narrowing is treated.
- Expect your voice to sound high-pitched while breathing it; this is harmless and goes away afterwards.
- Tell the team if you feel more breathless, as the oxygen content may need adjusting.
- It is not a home or everyday treatment and is only used under close supervision.
Weighing it up
Advantages & disadvantages of Heliox
Advantages
- Can make breathing easier through narrowed airways by flowing more smoothly than ordinary air.
- May reduce the effort of breathing and help buy time while other treatments work.
- Can help inhaled oxygen and medicines reach the lungs in some difficult situations.
Disadvantages
- Supports breathing but does not treat the underlying cause of the narrowing.
- The mixture carries a limited amount of oxygen, so enough oxygen must always be ensured.
- A specialist hospital treatment, not something used routinely or at home.
Practical use
Good to know
The most important safety point with heliox is oxygen: because the benefit depends on having plenty of light helium in the mixture, the proportion of oxygen is lower than people sometimes need, so the team carefully ensures enough oxygen is delivered and watches oxygen levels closely. Heliox is a supportive measure that eases the effort of breathing while the real cause of the airway narrowing is treated; it is not a cure on its own. A harmless and temporary effect is that breathing helium makes the voice sound squeaky or high-pitched, which returns to normal afterwards. It is a specialist hospital treatment, given through a mask or breathing circuit by trained staff, and is used in selected emergencies rather than routinely.
Who should not take it / use with caution
- It is not suitable for people who need a high proportion of oxygen that the mixture cannot provide.
- It is used with care, with close monitoring of oxygen, in anyone who is very low on oxygen.
- It should only be used in hospital under specialist supervision.
Monitoring
- Close monitoring of oxygen levels to make sure enough oxygen is being delivered.
- Watching the effort of breathing and overall response while it is being used.
- Reviewing whether the underlying cause is improving so the gas can be stopped when no longer needed.
Side effects
- A harmless, temporary high-pitched change in the voice while breathing the gas.
- A risk of not getting enough oxygen if the mixture is not managed carefully, which the team monitors.
- Discomfort from the mask or breathing circuit in some people.
Key interactions
- It is used alongside, not instead of, the treatments aimed at the underlying airway problem.
- It can be used to help deliver inhaled medicines, coordinated by the specialist team.
- There are no routine medicine interactions, but its oxygen content must be balanced with the person's needs.
Available as: A helium-oxygen gas mixture breathed in through a mask or breathing circuit.
Answers
Heliox: frequently asked questions
What is heliox used for?
It is a helium-oxygen gas mixture breathed in to help air move more easily through narrowed airways in certain emergencies, easing the effort of breathing.
How does it help breathing?
Helium is much lighter than the nitrogen in normal air, so the mixture flows more smoothly through tight airways, reducing the work of breathing.
Why does it change my voice?
Breathing helium temporarily makes the voice sound high-pitched; this is harmless and returns to normal once you stop breathing the gas.
Does it cure the breathing problem?
No. Heliox supports breathing while the underlying cause of the airway narrowing is treated; it is not a cure on its own.
Is it safe for oxygen levels?
The mixture carries a limited amount of oxygen, so the specialist team always makes sure enough oxygen is given and monitors your oxygen closely.
Authoritative sources
- BNF
- NICE CKS
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