Undiluted nitrous oxide - as it was used in the nineteenth century - can cause hypoxia. Hypoxia occurs when the body is deprived of an adequate oxygen supply, leading to dizziness and other problems. Fortunately scientists have found that combining nitrous oxide with oxygen all but eliminates the danger of hypoxia. This mixture is now used to calm many millions of anxious patients annually, all around the world. Nitrous oxide and oxygen sedation is used not only in dental offices but in hospitals and outpatient and inpatient settings.