Consumer medicine information

Nitrous oxide Medical EP Grade

Nitrous oxide, N2O

Consumer Medicine Information

What is in this leaflet

This leaflet answers some common questions about nitrous oxide. It does not contain all the available information.

It does not take the place of talking to your doctor, anaesthetist, surgeon or dentist.

All medicines have risks and benefits. Your doctor or dentist has weighed the risks of you using nitrous oxide against the benefits they expect it will have for you.

If you have any concerns about using nitrous oxide, ask your doctor or dentist.

Keep this leaflet with you, you may want to read it again.

What Nitrous oxide is used for

Nitrous oxide is a gas used for general anaesthesia or pain relief.

It is usually given with another anaesthetic gas and oxygen during surgery via a tube placed down your throat by an anaesthetist or given with oxygen via a mask by your doctor or dentist.

Nitrous oxide works by causing unconsciousness (deep sleep) before and during surgery and by relieving pain for certain procedures.

Your doctor may prescribe nitrous oxide for another purpose. Ask your doctor if you have any questions about why nitrous oxide has been prescribed for you.

This medicine is available only with a doctor’s prescription.

Before you use Nitrous oxide

When you must not use it

Do not use nitrous oxide if:

  1. You have an allergy to nitrous oxide or any other component in the gas or have had an allergic reaction in the past.
  2. You have a condition where air is entrapped within your body and it might expand when given nitrous oxide (eg bowel obstruction, blocked middle ear, following a recent dive). Ask your doctor for full details of these conditions.
  3. You have been using it for a prolonged period without proper monitoring of your blood.
  4. Do not use nitrous oxide without the necessary amount of oxygen.
  5. You are intoxicated.

Do not use nitrous oxide if the cylinder is damaged or shows signs of tampering or it has degraded.

Before you start to use it

You must tell your doctor or dentist if:

  1. You are allergic to any other medicines, foods, dyes or preservatives.
  2. You have had a reaction to nitrous oxide or any other general anaesthetic or pain relief medication in the past.
  3. You have had a general anaesthetic or surgery in the past.
  4. You have or have had any other health problems or medical conditions, including:
  • A condition known as malignant hyperthermia or a family history of it.
  • Low blood pressure
  • Low vitamin B12 levels
  • Problems with addiction to medicines
  • Bone marrow problems including various cells in the blood
  • Neurological diseases
  • Conditions in which air is entrapped within the body
  1. You are pregnant or intend to become pregnant.

Your doctor or dentist will discuss the risks and benefits of using nitrous oxide when pregnant.

  1. You are breastfeeding or wish to breastfeed.

Your doctor or dentist will discuss the risks and benefits of using nitrous oxide when breastfeeding.

  1. Care should be taken when using nitrous oxide as it is stored under high pressure in gas cylinders. Contact with eyes or skin may result in cold burns. There are also safe working exposure levels and important storage instructions. Please discuss these with your doctor if you have any questions.
  2. You have had long term usage or been chronically exposed to nitrous oxide.
  3. You have had eye surgery within the last four weeks and a gas was used in your eye during the procedure.

Taking other medicines

Tell your doctor or dentist if you are taking any other medicines, including medicines you buy without a prescription from a pharmacy, supermarket or health food shop.

Some commonly used medicines that may interfere with nitrous oxide include:

  • Pain relievers
  • Anaesthetics
  • Methotrexate
  • Medicines which may effect your nervous system

These medicines may be affected by nitrous oxide or may affect how well it works. You may need to take different amounts of your medicine or you may need to take different medicines.

Some medicines may affect the way others work. Ask what to do when using nitrous oxide with other medicines.

Your doctor may have more information on medicines to avoid while using nitrous oxide.

If you have not told your doctor about any of the above, tell them before you start using nitrous oxide.

How to use Nitrous oxide

Nitrous oxide should only be used under the supervision of your doctor or dentist.

How much to use and how to use it

The amount of nitrous oxide given to you will be decided by your doctor or dentist, depending on the amount of pain relief or sleep required. It is usually given to you by breathing it through a mask or by a tube placed down your throat during surgery.

If you are elderly or have lung problems, you may need a lower amount of nitrous oxide.

Follow all directions given to you by your doctor or dentist carefully.

These directions may differ from the information contained in this leaflet.

If you do not understand the instructions, ask your doctor for help.

How long to use it

Your doctor will decide for how long you need to use nitrous oxide.

If you use too much (overdose)

As nitrous oxide is most likely to be given to you in hospital under the direction of your doctor, it is very unlikely you will receive an overdose. However, if this happened, quick action can be taken to maintain your breathing and replace the nitrous oxide with more oxygen.

If you have any questions then ask your doctor.

After you have used Nitrous oxide

Things you must not do

Following a general anaesthetic:
Do not drive or operate machinery for at least 24 hours after using nitrous oxide.

General anaesthetics may cause a slight decrease in intellectual function and alertness for 2 to 3 days in some people.

Ask your doctor when it is safe for you to drive, operate machinery or perform activities following the use of nitrous oxide.

Following analgesia:
Ask your doctor or dentist when it is safe for you to drive, operate machinery or perform activities following the use of nitrous oxide.

Side effects

Tell your doctor or dentist as soon as possible if you do not feel well while you are using nitrous oxide.

Nitrous oxide may have unwanted side effects in some people. All medicines can have side effects. Sometimes they are serious, most of the time they are not. You may need medical treatment if you get some of the side effects.

Ask your doctor any questions you may have.

Tell your doctor or dentist if you notice any of the following and they worry you:

  • Nausea, vomiting
  • Headache, dizziness

These side effects are usually mild.

Tell your doctor or dentist immediately if you notice any of the following:

  • Confusion, excitation, depression
  • Breathing problems
  • Heart problems
  • Pins and needles, changes in sensation
  • Bleeding, fits
  • Abdominal pain, bloating
  • Addiction

These are serious side effects. You may need urgent medical attention. Serious side effects are rare. Other side effects may occur as a result of your operation or other medications and anaesthetics received, so check with your doctor or dentist if you have any concerns.

If any of the above happen, tell your doctor or dentist immediately or go to casualty at your nearest hospital

Other side effects not listed above may also occur in some patients. Tell your doctor or dentist if you notice anything else that is making you feel unwell.

Ask your doctor or dentist if you don’t understand anything in this list.

Do not be alarmed by this list of possible side effects. You may not experience any of them.

After using Nitrous oxide


Nitrous oxide is stored at ambient temperature in cylinders by your doctor or hospital under specific instructions.


All cylinders are the property of the manufacturer as indicated on the label . All cylinders are returnable to the manufacturer.

Product Description

What it looks like

Nitrous oxide is a clear, colourless, slightly sweet smelling, non-irritating gas supplied in blue (ultramarine) cylinders as determined by AS4484

Cylinder sizes include: 1.5L, 3.0L, 10L, 25L, 35L, 50L as measured by nominal water capacity.


Nitrous oxide- 98% v/v min

Carbon dioxide- 300ppm v/v max
Carbon monoxide- 5ppm v/v max
Oxides of nitrogen- 2ppm v/v max
Water (vapour)- 67ppm v/v max

Manufacturer/Distributor/ Supplier

BOC Gases Australia Limited
Riverside Corporate Park
10 Julius Ave.
North Ryde NSW 2113

AUST R 34466

This leaflet was prepared in September 2001 and modified on the 27 March 2008..

Published by MIMS September 2019