Home » Dentistry » Nitrous Oxide (N2O) or Laughing Gas

What is N2O? | How N2O works? | Pros | Cons | Use in Dentistry | Side effects | Safety | Conclusion

Does visiting a dental clinic make you tense or seeing dental tools trigger anxiety? You are not alone who feel mental resistance, as there are a lot of people who avoid visiting a dentist until the pain becomes unbearable. Unfortunately, one cannot avoid visiting a dentist forever, so dentists use a suitable sedative to deal with patients’ anxiety. Whether it is simple teeth cleaning or a delicate invasive procedure, your dentist will use FDA approved sedative to manage anxiety and pain. Nitrous oxide is among the most popular dental anesthesia in use since the mid-1800s. Popular as “laughing gas”, “conscious sedative” or “relative analgesia”, N20 is known for causing central nervous system depression and euphoria, without affecting the respiratory system. Out of total sedation used in dental practices, over 70% use nitrous oxide-oxygen sedation, so it is relatively safe if administered as per prescribed guidelines by professionals.     

What is Nitrous Oxide?

Nitrous Oxide (N2O), a colorless inorganic gas with a pleasant sweetish odor and taste, is the most widely used gaseous anesthetic to produce insensibility to pain and a sense of euphoria, sometimes laughter. This analgesic / anxiolytic agent depresses the central nervous system, thus the patient feels calm and relaxed. Popular as “laughing gas”, N2O works fast and the sedative effect wears off easily. Dentists use the nitrous oxide-oxygen gas combination to eliminate the pain and anxiety of patients in the conscious state so that s/he could respond to verbal commands, normally. It is good for children as nitrous oxide will keep them relaxed and stable while the dentist is performing a dental procedure. It is safe, but just like any other drug side-effect may occur if administration and recovery guidelines are not followed properly.    

How Does Nitrous Oxide Work?

It is known commonly as “laughing gas”, and this is because of the way it plays with the central nervous system to create a sense of euphoria. Nitrous oxide, first synthesized in 1772 but in use as medical anesthesia since 1844, is administered through the nasal hood. Depending on the severity of anxiety, your doctor will change the proportion of nitrous oxide and oxygen to get the desired strength of sedation. Following the first inhalation, it takes just 20 seconds to reach the brain and another 2-3 minutes to show the pain inhibiting effect.  

Nitrous oxide does not combine with hemoglobin and is transported in the blood as free gas. Since it does not undergo biotransformation, the onset time of this agent is the fastest among inhalation sedatives. The low solubility of nitrous oxide gas in blood and adipose tissue allows speedy exhalation, meaning quicker normalization.   

How nitrous oxide functions in the human body is not exactly known. Scientists believe that nitrous oxide works through regulated ligand-gated ion channels in the body, thus affecting how neurotransmitters send pain signals across the body.

Following administration of nitrous oxide, GABAA receptors block neurotransmitters, triggering an anti-anxiety effect. Studies show that once nitrous oxide reaches the brain it triggers the release of norepinephrine, thus inhibiting the spread of pain signals. The sense of euphoria among patients suggests that nitrous oxide affects dopamine release as well.

Depending on the amount of gas inhaled, the reaction of light-headedness, warmness, euphoria, and sleepiness could vary. Although rare, some patients report feeling of vibration or floating sensation and mild dizziness. If feeling uncomfortable, inform your doctor as he could control it by decreasing the nitrous oxide flow and increasing the oxygen flow.

Following completion of the dental procedure, your doctor will turn off the valve of nitrous oxide and continue the oxygen flow. It will slowly eliminate the nitrous oxide from the body from the lungs and airways. Most patients return to their normal state in a few minutes, but one should consult their doctor before starting to eat and driving. Nitrous oxide can affect appetite and motor skills temporarily, so it is better to feel confident first than start driving.

Nitrous oxide irreversibly oxidizes vitamin B12, thus reducing the effectiveness of B12-dependent enzymes. So, if you are on certain medication related to infertility, abortion, or neurological ailments you should inform the anesthesia specialist to avoid any complication.


  • N2O is very easy to administer via nasal path
  • It starts action almost instantly, in just 2-3 minutes
  • No anxiety
  • Feeling of euphoria
  • Unlike other anesthesia, nitrous oxide has a non-irritating pleasant odor
  • It gets eliminated almost instantly so there won’t be any hangover effect
  • You are ready to eat and drive almost instantly after the recovery
  • The sedative effect could be controlled according to the patient’s comfort
  • The patient remains conscious to respond to verbal communication
  • Normal cardio-respiratory stability
  • Patients’ reflex integrity maintained
  • No need for preparation
  • Post-procedure, no assistance is required


  • Most of the disadvantages are related to administration-related overdose, so if an overdose happens patient might feel nauseated and sleepy.
  • Nitrous oxide administration equipment is expensive
  • Your nose should be clear for breathing as any blockage could affect the flow of nitrous oxide and oxygen

Nitrous oxide sedation in dentistry

When it comes to choosing between excruciating pain and anxiety, there is no option but to visit a dentist to get rid of dental ailments at the earliest. Fortunately, you have the nitrous oxide sedative to control anxiety and pain. Administration of laughing gas will make your treatment process joyful. It is necessary for you, if:

  • Your pain threshold is low, meaning you cannot endure even mild discomfort
  • Seating in a dental clinic makes you uncomfortable
  • You cannot sit still in the chair
  • Seeing dental tools makes you nervous
  • Your teeth are hyper-sensitive
  • You cannot control reflex during the dental procedure
  • Your dental procedure is invasive and needs pain management
  • Your child has fear of seeing a dentist

You might not be eligible for nitrous oxide sedation during the dental procedure, if:

  • You are less than three months pregnant
  • You are suffering from a respiratory ailment
  • You have chronic obstructive pulmonary disease (COPD)
  • You have a vitamin B-12 deficiency
  • You have neurological conditions or on some related medications
  • You consume sedative drugs
  • You are on medication for sleep amnesia
  • You have cardio-respiratory conditions   

Side Effects

Administering nitrous oxide can have potential side effects, although mostly short-term, but this is only because of existing conditions or the wrong dose. Side effects occur when patients inhale too much gas or inhale too fast. Some of the common short-term side effects of nitrous oxide sedation are:

  • The patient might show signs of excessive sweating
  • In some cases, the patient might start shivering
  • Inhaling gas too much or too fast could cause nausea
  • If pre-administration guidelines are not followed patient might vomit
  • If not exhaled thoroughly, the patient might experience dizziness
  • Some patients, especially, old age complain about fatigue due to oxygen deficiency
  • Some patients, very rarely, might experience delusion or sound distortion.

If nitrous oxide is administered without oxygen, your doctor might give your oxygen five minutes after the nitrous oxide supply is turned off to boost clearing the gas from the chest and airways. This helps in regaining alertness faster and prevents headache and dizziness. In normal cases, it takes just around 14 minutes to regain alertness, so ideally one should wait for 15-20 minutes before starting driving. To prevent nausea and vomiting, you should avoid heavy meals before nitrous oxide administration. Doctors advise avoiding meals for 2-3 hours after you regain alertness.

Is Nitrous Oxide Safe for Children?

Children naturally fear facing a dentist, so they react during the dental procedure. Excessive physical movement could be dangerous for your kid, so dentists recommend administering conscious sedatives like nitrous oxide to manage pain and anxiety. It is completely safe to administer nitrous oxide to reduce anxiety, according to the American Academy of Pediatric Dentistry (AAPD).  The American Dental Association also recognizes nitrous oxide as a safe sedative agent for children. So, you need not worry as it has an excellent safety record.  


Nitrous oxide is one of the most effective and safe conscious sedatives, so it is used as per the standard regulatory guidelines to make dental procedures less traumatic. Once administered, you will remain conscious to see things happening, but won’t feel the pain so there won’t be reflexive actions. This helps dentists perform the dental procedures with perfection and help patients get the best treatments with the least pain and anxiety. It is perfectly safe to use, but if you experience any symptoms of side effects, you should let your attendant know about it immediately, so that he could control the flow of nitrous oxide. If you are on some kind of medication, you should inform the anesthesia professional in advance, as it could be life-threatening in some conditions. The safety aspect is all about dose, so you should consult only certified dentists, trained to administer nitrous oxide.  



Published by Dr. Daniel Bronsky

Dr. Daniel is an orthodontist at Invis London.

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