Nitrous oxide is used during dental treatment with the intention of easing anxiety in patients. Administration of the gas typically produces pleasant sensations that can help a patient relax. This is the desired level of sedation when using nitrous oxide in a dental setting. The sensations patients may experience with nitrous oxide include:

• Mental and physical relaxation
• Indifference to surroundings/time
• Lessened awareness of pain
• Tingling in the hands and feet
• Numbness in hands, feet, thighs, mouth or tongue
• Feeling of heaviness or lightness
• Floating sensation
• Presence of droning sounds (a constant, monotonous tone)
• Hearing that is distinct, although sounds seem distant
• Drowsiness
• Warmth
• Euphoria (may include dreaming, laughing, giddiness)
• Dissociation (alteration in a person’s sense of self)
• Slurred speech
• Slower-than-normal response time
• Decreased motor control

Approximately 15 percent of people who receive nitrous oxide experience negative side effects. This may occur due to too high a concentration of nitrous oxide in the gas, or from a sudden change in the amount of nitrous oxide a patient inhales. Negative side effects of nitrous oxide may include:

• Headaches
• Nausea, vomiting
• Excessive sweating or shivering
• Vertigo (sense of spinning, dizziness)
• Increased sleepiness
• Unconsciousness

Patients who experience any discomfort while receiving nitrous oxide should inform the dentist immediately. Headaches may occasionally result when patients do not receive oxygen for at least five minutes after the nitrous oxide has been turned off. This helps to flush any remaining gas from the lungs and return patient to a fully awake and alert condition.

Patients may be advised to keep meals light prior to dental appointments in which nitrous oxide will be used because of the risk of nausea and vomiting. Patients may also be advised to avoid heavy meals for three hours after the appointment.

Some studies have shown that a patient’s motor skills and attention may be affected for 15 minutes after the use of nitrous oxide. Patients may wish to wait this long before driving. If in doubt, patients are advised to ask their dentist whether it is safe for them to drive after receiving nitrous oxide.