Nitrous oxide (medication)
| Entonox CD cylinder and giving set | |
| Combination of | |
|---|---|
| Nitrous oxide | Analgesic gas (usually 50%) | 
| Oxygen | Medical gas (usually 50%) | 
| Clinical data | |
| Trade names | Entonox, Nitronox, others | 
| Routes of administration | Inhalation | 
| Drug class | NMDA receptor antagonist; Dissociative hallucinogen; Analgesic; General anesthetic | 
| ATC code | |
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| Legal status | 
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| Pharmacokinetic data | |
| Metabolism | Not metabolized | 
| Metabolites | None | 
| Onset of action | 30 seconds | 
| Duration of action | 1 minute | 
| Excretion | Exhaled | 
| Identifiers | |
| CAS Number | 
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| PubChem CID | |
| DrugBank | |
| ChemSpider | |
| UNII | 
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| ChEBI | 
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| ChEMBL | 
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| Chemical and physical data | |
| Formula | N2O | 
| Molar mass | 44.013 g·mol−1 | 
| 3D model (JSmol) | 
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Nitrous oxide, as medical gas supply, is an inhaled gas used as pain medication, and is typically administered with 50% oxygen mix. It is often used together with other medications for anesthesia. Common uses include during childbirth, following trauma, and as part of end-of-life care. Onset of effect is typically within half a minute, and the effect lasts for about a minute.
Nitrous oxide was discovered between 1772 and 1793 and used for anesthesia in 1844. It is on the World Health Organization's List of Essential Medicines. It often comes as a 50/50 mixture with oxygen. Devices with a demand valve are available for self-administration. The setup and maintenance is relatively inexpensive for developing countries.
There are few side effects, other than vomiting, with short-term use. With long-term use anemia or numbness may occur. It should always be given with at least 21% oxygen. It is not recommended in people with a bowel obstruction or pneumothorax. Use in the early part of pregnancy is not recommended. It is possible to continue breastfeeding following use.