Why laughing gas is no laughing matter

Occasionally I see lying in the road the tiny used silver canisters or whippits that contain laughing gas. The nitrous oxide gas – once used only by dentists to take the edge off the pain while drilling teeth – is now a common street drug.

In medical use, N2O is always combined with oxygen to minimise the risk of going short of oxygen, but recreational users inhale it neat.

Although the medical use of N2O in anaesthesia has been declining in the UK and elsewhere, its popularity as a recreational drug has increased despite the UK’s Psychoactive Substances Act 2016, prohibiting the sale of nitrous oxide for recreational use.

Outside of healthcare, the gas is sold legally as an engine accelerant in the motor industry and as a propellant in the production of whipped cream.

Small metal whipped cream chargers (whippits) or canisters, each containing 8g of compressed gas, are a common source of N2O for recreational use. Boxes of N2O canisters are cheap and easy to buy from shops, street dealers and social media or mainstream websites. Pre-filled balloons of N2O can also be bought.

The effects of N2O include dizziness, vomiting and fainting.

Inhalation of N2O, particularly in enclosed spaces, can lead to oxygen starvation and asphyxiation. Although N2O inhalation is rarely fatal, at least three deaths have been attributed to N2O in the UK in each of the past five years, with eight cases in 2016.

Prolonged exposure to N2O can lead to damage to the nerves of the hands and feet, and a very serious degeneration of the spinal cord. N2O interacts with the cobalt in vitamin B12 (cobalamin), and stops it working – leading to nerve and spinal cord injury.

One theory is that vitamin B12 inactivation interferes with the protective fatty coats of nerves which are necessary for the passage of nerve signals.

Something similar happens in multiple sclerosis.

Patients whose nerves or spinal cord are damaged experience numbness, tingling and unsteady walking. Vitamin B12 levels are often low. Patients with these nervous complaints have admitted inhaling N2O on average two to three times a week, and in large quantities (sometimes more than 100 canisters a day).

Mood changes, bladder and bowel disturbance, and erectile dysfunction are also seen after habitual use.

The No Laughing Matter campaign in the London Borough of Tower Hamlets is targeting antisocial behaviour and littering associated with N2O use, as well as the illegal sale.

Inhalation can lead to serious conditions