What is the annual death rate associated with nitrous oxide (N2O) abuse?

Annual Death Rate Associated with Nitrous Oxide (N2O) Abuse

There is no established annual death rate specifically for nitrous oxide abuse, as deaths are rare but can occur primarily through asphyxiation or severe complications from vitamin B12 deficiency.

Mechanisms of Mortality from N2O Abuse

Asphyxiation

• N2O displaces oxygen in closed spaces, which can lead to asphyxia and death 1
• Fatal accidents have been reported due to asphyxia (hypoxia) when using N2O 2
• Recent forensic cases have confirmed deaths from asphyxia due to N2O inhalation 3

Vitamin B12 Deficiency Complications

• Heavy or sustained use of N2O inactivates vitamin B12, resulting in functional deficiency 2
• This can lead to serious neurological complications and megaloblastic anemia
• Extreme homocysteine levels from N2O abuse can cause thrombotic events 4
  • In one study, 5% of patients who used N2O recreationally developed severe thrombotic events 4
  • These included arterial thrombosis (acute coronary syndrome, arterial thrombosis, cerebral thrombosis) and venous thromboembolisms

Risk Factors for Mortality

Usage Patterns

• Most recreational users consume N2O moderately:
  • Less than 10 balloons per episode
  • Fewer than 10 episodes per year 2
• Heavy users are at significantly higher risk:
  • Cases with thrombotic complications reported using 400-6000g (50-750 balloons) in a single day 4
  • Higher number of "hits" per session is associated with increased risk of accidental injury 5

Setting and Circumstances

• N2O is commonly used at festivals and clubs where other substances are also used 5
• Combined use with other substances may increase risks
• Use in enclosed spaces increases asphyxiation risk 1

Comparative Mortality Context

While specific annual death rates for N2O abuse are not established in the provided evidence, we can contextualize the risk:

• Carbon monoxide poisoning has a significant long-term mortality rate:
  • 24% of CO-poisoned patients died during follow-up (3 times the rate of matched national mortality data) 6
  • Among CO-poisoned patients with myocardial injury, 38% died during follow-up 6

Clinical Implications

Warning Signs

• Persistent numbness (reported by 4.3% of last-year users) 5
• Confusion and hallucinations (27.8% and 23.9% of last-year users) 5
• Neurological symptoms often precede thrombotic events (50% of cases) 4

Prevention Strategies

• Public education about risks of N2O use and appropriate harm-reduction strategies 5
• Recognition that N2O is increasingly popular (second most popular recreational drug after cannabis in the UK) 2
• Awareness that N2O is legal and widely available in most countries, making regulation challenging 2

Caveat

The available evidence does not provide a specific annual mortality rate for nitrous oxide abuse. Most deaths appear to be due to asphyxiation in acute settings or severe complications from chronic heavy use, but these appear to be relatively uncommon compared to the prevalence of use.