Nitrous
Standing risks
| Risk | Recorded values | Confidence | Article section |
|---|---|---|---|
| Chronic toxicity, limit exposure |
| high | View in article: Chronic toxicity, limit exposure |
Lethal interactions
| Combination | Type | Severity | Mechanisms | Confidence |
|---|---|---|---|---|
| GHB, GBL | Drug class | lethal | 2 | medium |
Dangerous interactions
29 dangerous interactions recorded for this substance.
See the full interactions tableContraindications
| Condition | Severity | Note |
|---|---|---|
| Respiratory | ||
| pneumothorax | absolute | Any closed gas-containing body cavity is an absolute contraindication. N₂O rapidly expands trapped gas, increasing pressure or volume in the cavity. |
| Neurological | ||
| pre-existing peripheral neuropathy or myelopathy | relative | Pre-existing neuropathy or myelopathy of any aetiology. N₂O's cobalamin inactivation adds metabolic injury to already compromised neural tissue. |
| Metabolic | ||
| vitamin B12 deficiency | absolute | Includes pernicious anaemia, strict vegetarian/vegan diet with inadequate B12 supplementation, malabsorption syndromes (Crohn's disease, coeliac disease, gastric bypass), and inherited disorders of cobalamin metabolism. Even a single prolonged exposure in B12-deficient individuals can precipitate myelopathy. |
| Pregnancy & Breastfeeding | ||
| first trimester pregnancy | relative | First trimester exposure carries theoretical teratogenic risk based on animal data. N₂O is widely used in later pregnancy (Entonox for labour analgesia) without documented harm from acute exposures. |
| Other | ||
| bowel obstruction | absolute | All closed gas-containing abdominal pathologies (bowel obstruction, ileus with significant gas) represent absolute contraindications due to gas expansion physics. |
| middle ear disease | absolute | Active middle ear pathology, recent tympanoplasty, or any condition with compromised eustachian tube drainage. |
| recent ophthalmic surgery with intraocular gas | absolute | Patients with intraocular gas bubbles from recent vitreoretinal surgery. SF6 bubbles persist 2-3 weeks; C3F8 bubbles persist 6-8 weeks. |