Inhalation Sedation (Laughing Gas)

Inhalation sedation, also known as relative analgesia (RA) or more commonly as laughing gas, uses a combination of (N2O) and oxygen (O2) to allow pain-free dentistry. At Crescent Dental Limerick we offer Inhalation Sedation to both adult and paediatric patients who find dental treatment particularly stressful. Dr Miriam Quilty is highly trained in this area of dentistry (currently completing a Diploma in Conscious Sedation from Trinity College Dublin).

What is it? And what does it do?

Nitrous oxide (N2O) is simply a gas which you can breathe in. It has no colour or smell and doesn’t irritate in any way. Nitrous oxide kills pain and induces a pleasurable feeling, making it an ideal solution for people who are frightened of undergoing dental treatment.

After 5 minutes or so of breathing in the gas, a euphoric feeling is induced which spreads throughout the body. You will feel a bit light headed and often people get ‘the giggles’ (hence the name laughing gas). As an interesting aside, nitrous oxide was one of the drugs of choice for young people in the late 1700s and early 1800s, when laughing gas was a popular source of entertainment and enjoyment.

How does nitrous oxide work?

Interestingly, the actual mechanism of action of N2O is still unknown (it appears that there are quite a few different mechanisms at work). However, it has been observed that N2O depresses almost all forms of sensation – especially hearing, touch and pain and that it also seems to disinhibit some emotional centres in the brain. The ability to concentrate or perform intelligent acts is only minimally affected, as is memory.

Depending on the concentration and length of administration of laughing gas, four levels of sedation can be experienced (after an initial feeling of light-headedness):

  • a tingling sensation, especially in the arms and legs, or a feeling of vibration (“parasthesia”), quickly followed by
  • warm sensations, and
  • a feeling of well-being, euphoria and/or floating. During heavier sedation, hearing may dissolve into a constant, electronic-like throbbing.

How is nitrous oxide administered?

The equipment used for delivering RA consists of pressurised cylinders of compressed gases and an apparatus which delivers the gases. Flowmeters and pressure gauges allow the dentist to keep an eye on the flow of gases. The mix is fed through a tube to which a nasal hood or cannula is attached. This hood is put over your nose. All you have to do now is breathe normally through your nose.

What are the advantages of nitrous oxide?

  1. Nitrous oxide works very rapidly – it reaches the brain within 20 seconds, and relaxation and pain-killing properties develop after 2 or 3 minutes.
  2. The depth of sedation can be altered from moment to moment, allowing your dentist to increase or decrease the depth of sedation.
  3. Other sedation techniques have a fixed duration of action (because the effects of pills or intravenous drugs last for a specific time span), whereas gas can be given for the exact time span it’s needed for.
  4. No injection is required. In cases of very severe needle phobia, getting laughing gas first can help you feel relaxed enough to allow the needle required for IV sedation to be inserted in your arm or hand.
  5. Inhalation sedation is very safe. It has very few side effects and the drugs used have no ill effects on the heart, lungs, liver, kidneys, or brain.
  6. Inhalation sedation has also been found to be very effective in eliminating or at least minimizing severe gagging..

Are there any contraindications?

There aren’t any major contraindications to relative analgesia, except for M.S., emphysema and some exotic chest problems. It hasn’t been proven to be safe during the first trimester of pregnancy, so you can’t use it then.

Because you have to breathe it in through your nose, it’s not suitable for people who have a cold or some other condition which prevents them from breathing through their nose.

You can’t be allergic to N2O. It’s also safe to use if you suffer from epilepsy, liver disease, heart disease, diabetes, or cerebrovascular disease. It is also used quite successfully in many people with respiratory disease – but it depends on the exact nature of the disease, so check with your dentist first.

Call Crescent Dental on 061 484 844 to schedule your appointment. You may be eligible for a free check-up; see

DentistryReva Dental