Nitrous Oxide Sedation Contraindications
Nitrous Oxide Sedation Dentistry

Nitrous Oxide Contraindications

Though nitrous oxide is considered as a suitable dental sedation method for the vast majority of patients with dental anxiety problems, there are some contraindications for nitrous oxide sedation. If it is a temporary condition (such as a cold) the dentist may postpone the treatment until the condition is resolved to minimize any risks. Medical consultation is recommended for nitrous oxide contraindications due to more permanent health conditions.

Contraindications of using Nitrous Oxide Sedation Dentistry

The currently known contraindications to the use of nitrous oxide sedation include the following:

Breathing problems – Lung conditions

Inhalation sedation is not indicated for people with respiratory problems (asthma or emphysema) or difficulty breathing in through the nose. Patients with a cold are better to avoid inhalation sedation until they can breath normally. Nitrous oxide is given by a nose mask, so if patients are unable to breathe adequately through their noses, they will be unable to inhale sufficient nitrous oxide for sedation. Conditions relatively contraindicating the use of nitrous oxide include:

  • Sinus infections (sinusitis)
  • Nasal blocking conditions such as colds, influenza or allergies.
  • Cystic fibrosis or
  • Chronic obstructive pulmonary diseases (COPD) such as emphysema and bronchitis.

Mental conditions – Drug abuse

Some patients report that during nitrous oxide sedation they had dreams even though they were fully conscious. These potentially mind-altering effects of nitrous oxide may be a contraindication in patients with some mental or psychiatric disorders, patients with drug addictions, and patients under the influence of drugs or alcohol.

Patients suffering from severe phobias of any kind, or taking sleep-inducing medication, antidepressants, or psychotropic drugs are at high risk of having hallucinations when sedated with nitrous oxide. Because of the fact that dreams or hallucinations some patients have may be of sexual nature, a dentist will not perform nitrous oxide sedation when there is no other person present in the room, in order to avoid false abuse claims.

Patients with conditions that do not allow proper understanding of the procedure and maintaining communication with the dentist are not suitable for inhalation sedation dentistry, which is based essentially in the patient’s responsiveness to dentist’s questions and instructions.

First trimester of pregnancy

The first trimester of pregnancy is the most difficult period of pregnancy when most of the complications occur. Several researches have linked chronic occupational exposure to nitrous oxide with an increased percentage of pregnancy complications including spontaneous abortion among pregnant women working in places where nitrous oxide is administered. No risk have been found for pregnant patients sedated with nitrous oxide, provided that the dentist monitors closely the N2O/O2 mixture and does not allow oxygen levels fall below the safety level.

However dentists prefer not to use nitrous oxide sedation during the first trimester, and they will always request the patient’s physician or obstetrician consultation, to avoid any risk of their treatment being linked with the possibility of a patient’s pregnancy complications. In general it is recommended that dental treatments should be avoided in the first semester, except if absolutely necessary.

Eye or ear surgery

Nitrous oxide should not be administered to patients who recently had eye surgery that involved introducing an intraocular gas. Nitrous oxide inhalation can result in the expansion of the gas bubble in the eye causing healing complications and possibly eye damage. Due to its physical properties, nitrous oxide moves into an air space faster than air moves out, thus it may cause a gas bubble in the body to expand by up to 10%.

Similarly, patients who recently had middle ear surgery (tympanic membrane graft) or have blocked eustachian tubes should not receive nitrous oxide sedation because the tympanic membrane can become distended and damaged following inhalation of the nitrous oxide.

Bleomycin therapy

Patients under anti-neoplastic therapy with bleomycin sulfate are contraindicated for the use of nitrous oxide sedation, due to the increased incidence of pulmonary fibrosis and other lung diseases. Patients undergoing bleomycin treatment for certain types of cancer are also predisposed to respiratory failure following exposure to high concentrations of oxygen over 25%. Since use of 100% oxygen is part of the standard sedation procedure (in both the initial and recovery phases) there is an increased risk of possible problems in these patients.


Because of its euphoric effect (it is not called laughing gas for no reason) you may want to avoid nitrous oxide if you are too much afraid of getting embarrassed. The several videos in the web have proven that you may do or say some silly things when sedated.

Depending on the patient’s condition and the specific type of contraindication for the use of nitrous oxide sedation, the dentist may recommend the postponement of the treatment or propose a more suitable dental sedation method.

next page -> Possible Side Effects of Nitrous Oxide Sedation
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