Inhalation Sedation

Photo of dentist Gordon Laurie BDS
Written by the Dental Fear Central Web Team and reviewed by Gordon Laurie BDS, a specialist in Special Care Dentistry
Last updated on September 18, 2022
A line drawing of a girl with a nitrous oxide mask. Inhalation sedation makes you feel floaty and relaxed.

Inhalation sedation (or “happy air”) works by breathing nitrous oxide. It allows you to feel relaxed while in the chair, and this can make everything that bit easier. People can also recall their positive experiences as happy air doesn’t affect their memory. This can help build confidence, trust and self-belief.

There are many different words for inhalation sedation, for example, laughing gas, relative analgesia, happy air, nitrous oxide, N2O-O2, but they all refer to the same thing.

What is nitrous oxide? And what does it feel like?

Nitrous oxide is an odourless gas which you breathe in via a nosepiece. It’s a great drug – it makes most people feel lovely and relaxed and maybe a bit floaty.

After about 5 minutes of breathing nitrous, you should feel a warm and fuzzy feeling spread throughout your body. In the video below, Gregor, a patient at the Berkeley Clinic in Glasgow, explains what inhalation sedation feels like:

First-hand accounts of inhalation sedation from our forum

I had nitrous when I had a tooth extracted because I was extremely nervous about it. I also briefly considered IV sedation but that gave me more anxiety than the thought of the extraction itself (loss of control). The nitrous was fine. I felt completely aware the whole time. No nausea or vomiting. Since it’s just a cup over your nose you can tell them if you feel unwanted side effects and they can adjust the dose quickly or remove it entirely. It also wears off quickly. I found it helped me relax and occasionally let my mind drift away from the procedure. I also listened to relaxing music during. The nitrous did not make me feel drunk or high or giddy. I felt just like myself but not super-stressed and anxious as I would have been otherwise.

You start with O2 and a few minutes later he asked how I was doing and basically, nothing happened so he had to increase it a couple of times and finally I started to relax a bit. No real loopiness but just a sense of “yeah I can get thru this”. The biggest sensation was my legs felt kinda heavy as if to say maybe I want to stay here a while. Thinking like that I knew the gas was definitely working!! I WANTED TO STAY AT THE DENTIST!!!! Can you believe this?

How does nitrous oxide work?

The nitrous oxide you get at the dentist’s is not the same as “laughing gas” used as a recreational drug (pure nitrous oxide). Instead, it’s a mixture of nitrous oxide (N2O) and oxygen (O2). You can only inhale pure nitrous oxide safely for a short period of time without any ill-effects. That’s why oxygen is added.

Nitrous is delivered by increasing the concentration of nitrous oxide a wee bit at a time until you’re happy and relaxed.

There are four levels of sedation, depending on the concentration and length of time you’ve been breathing it in for:

  1. a tingling sensation, especially in the arms and legs, or a feeling of vibration, quickly followed by
  2. warm sensations, and
  3. a feeling of well-being, euphoria and perhaps floating.
  4. At a deeper level of sedation, people feel sleepy and find it difficult to keep their eyes open or to speak. This “dream” stage means that the N2O concentration may be too high, and there can be side effects.

With inhalation sedation, you’ll want to stay within the first three levels.

Some people get a feeling of lightheadedness after 60 or 90 seconds. This will pass as the concentration of N2O is increased.

Interestingly, the exact mechanism of action of N2O is still unknown. What we do know is that N2O seems to depress almost all forms of sensation – especially hearing, touch and pain. It also reduces anxiety. You can still concentrate and think quite clearly, and won’t have the memory loss you get with IV sedation.

How is it given?

For inhalation sedation, you need a supply of compressed gases (oxygen and nitrous oxide) and a machine which mixes the oxygen and nitrous oxide. The administrator selects the desired mix and the flow rate, using knobs or dials. The very latest machines even feature touch screens!

An ultra-modern nitrous oxide device, complete with touch screen

The mix of gases is fed through a tube that has a nosepiece attached. Actually, the nosepiece is a sort of double mask, consisting of an inside and an outside mask. The inside mask goes over your nose. Some inside masks are scented – popular fragrances include vanilla, strawberry, blueberry and apple.

The outside mask connects to a vacuum machine which sucks the waste gas away. You wouldn’t want your dentist to get a faceful of nitrous… then again, you might, just for a laugh ?.

Clear outside mask and scented red inside mask

Anyways… all you have to do now is breathe normally through your nose – bingo!

What are the advantages of inhalation sedation?

  • It kicks in very quickly. It reaches the brain within just 20 seconds, and relaxation and pain-killing effects set in after 2 or 3 minutes.
  • You can deepen or lessen the level of sedation almost instantly.
  • It wears off quickly, within about 5 minutes, so you won’t need an escort. What’s more, you can even drive yourself home.
  • For certain things such as deep cleaning, it may be possible to use nitrous instead of numbing shots. N2O acts as a painkiller on soft tissues such as gums. But the effect varies a lot from person to person.
  • If you have a needle phobia and you want to have IV sedation, inhalation sedation may relax you enough to allow the IV needle into your arm or hand.
  • It’s incredibly safe and has very few side effects. There are no ill effects on the heart, lungs, liver, kidneys, or brain.
  • Inhalation sedation can help with a severe gag reflex.

Are there any disadvantages?

  • It doesn’t work if you can’t breathe through your nose.
  • Some people are not comfortable with the idea of any kind of sedation.
  • If you feel claustrophobic or panicky when something is put over your nose, it may not be for you.
  • If you want a very deep level of sedation, nitrous oxide may not be enough.
  • There may not be any dentists who offer nitrous oxide in your area.
  • The equipment and gases are expensive, so you’ll probably have to pay for it. Still, it’s quite a bit cheaper than IV sedation.
  • Nitrous oxide is a greenhouse gas. Altogether, nitrous oxide contributes about 5% to the greenhouse effect. But most of this is from agriculture and the burning of fossil fuels and forests. Only a tiny fraction is from medical uses.

Are there any contraindications?

There aren’t many major contraindications, except for emphysema and some exotic chest problems. Also, you can’t use nitrous oxide during the first three months of pregnancy, because we don’t know whether it’s safe to do so.

If you have a vitamin B12 deficiency and receive injections for this, you need to avoid nitrous oxide. Why? Because the gas inactivates the B12 in your blood so your body can’t use it. But this only applies to people who have a problem with absorbing B12 from their diet.

You can’t be allergic to N2O. It’s safe to use if you have epilepsy, liver disease, heart disease, or diabetes. Many people with lung problems can also use it successfully – but it depends on the exact nature of your condition, so check with your dentist!

I’ve had a bad experience with laughing gas in the past – have things changed?

If you had an experience in the past where nitrous oxide made you feel sick, it was administered badly!

Nowadays, most dentists who use nitrous oxide are aware of the need to gradually increase (“titrate”) the N2O concentration. This is because everyone is unique and reacts differently, and people’s tolerance can vary from day to day.

Perhaps this wasn’t always the case – many years ago, dentists used nitrous oxide with very little in the way of training (and such training wasn’t readily available back then). As a result, some people ended up with nausea, dizziness or vertigo.

This is how titration works: you start off by breathing 100% oxygen. Then, you add 10% to 20% nitrous oxide. The nitrous oxide is then gradually increased by 5% to 10% increments every 1 to 3 minutes until you’re happy with the level of sedation. The “standard” mix nowadays is 30% nitrous oxide and 70% oxygen. But if you need more, you can use more – up to a maximum of 70% nitrous oxide. At the end of the appointment, you breathe in 100% oxygen for at least 5 minutes, or until you no longer feel any effects.

Of course, if you were to have any unwanted side effects at any stage, just let your dentist know. That way, they can adjust the concentration of N2O – the effects are almost immediate!

Is nitrous oxide the same as gas and air?

In medicine and especially in labour, sometimes a mix of 50% oxygen to 50% nitrous oxide is used. This is called Entonox or, more commonly, “gas and air”. For some people, 50% nitrous is too much, and nausea is quite common. The mix given to most dental patients, on the other hand, is only 30% nitrous oxide (and 70% oxygen).

How do I know if it’s for me?

Why not ask if you can have a 5-minute ‘sample’ so that you know what to expect on the day of your procedure?

Many thanks to Gordon Laurie for his help with writing this page. Artwork © Emma Laurie. All rights reserved.

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