A RECENT small US study of patients with treatment resistant depression has suggested that inhaled nitrous oxide, administered in a doctor’s office at regular intervals, may improve patients’ symptoms.

Dr Zak Uddin tells The Northern Echo more.

The researchers noted that patients reported feeling better at the two-week interval, but by the three-month mark, the differences between those given nitrous oxide versus a placebo were negligible and not enough to confidently argue it definitely had a beneficial effect.

Nitrous oxide was first discovered in 1773, with its recreational use made popular in the 1800s by the likes of Humphrey Davy.

Participants would inhale the gas from oiled silk purses. It’s application in medicine came later. Currently it is employed as an analgesic and sedative, for example in dentists, as well as a general anaesthetic.

It is also used in the motor industry, often referred to as nitrous or NOS, enhancing the power of performance cars.

It is known as a dissociative anaesthetic, meaning it produces feelings of floating. Other reported effects are mood enhancement through to euphoria.

However, some describe feeling anxious and even paranoid. These are usually short-lived, typically two to three minutes, often ending with giddiness and uncontrollable laughter, hence the term “laughing gas”.

It acts on the same receptors as ketamine, another anaesthetic agent, also used by psychiatrists in patients with severe depression that has not responded to conventional treatments. Ketamine is also a horse tranquiliser. Like nitrous oxide, it has been abused as a recreational substance.

Nitrous oxide is available legally. Its most commonly marketed use is as a food additive, being a propellant in whipped cream. However, its consumption as a recreational drug is growing.

In a 2019 poll of 16–24-year-olds, over 500,000 had experimented with the substance, with only cannabis being more popular. Part of its popularity is ease of access, typically in less than twenty-four hours online.

Its purchase is governed by the 2016 Psychoactive Substances Bill, hence purchasing without intent to supply is acceptable, however supplying could result in an unlimited fine and up to seven years in prison.

So, is it just a laughing matter? Advocates of its use, including the Psychedelic Society, would argue yes. If you purely use number of deaths then that argument stands strong compared to other illegal as well as legal recreational substances. With around five deaths per year in England and Wales, it is far outstripped by those due to cannabis, ecstasy, alcohol and tobacco.

Yet with increased use, we are able to understand a greater amount about complications both short and long term. It is stored at minus forty degrees centigrade, so if inhaled directly from cartridges (also known as bulbs or whippets) or a tank, it can cause cold burns to the nose, lips and throat. Indeed, it can even affect the vagus nerve at the back of the throat, dangerously slowing down the heart. As it is pressurised, direct inhalation may rupture lung tissue causing it to collapse.

Because it affects the senses, albeit temporarily, there is the chance of injury, both to self and others. Clearly this risk will be magnified if nitrous oxide is combined with other substances, either legal or illegal.

Because its use is short lived, users may consume multiple cartridges. There is the potential for blood oxygen levels to drop dangerously low. This is more common if inhaled from a tank, or the exceedingly risky practice of placing a plastic bad over the head while using. Deaths immediately following inhalation have been reported, as well as numerous incidents of injury by misadventure.

Regular use interferes with the vitamin B12, needed for nerve function. Permanent damage to the spinal cord and even paralysis have been reported. It also affects white blood cells, part of the body’s immune system. Although the above study looked at its role in the treatment of depression, regular long term recreational use of is linked to psychiatric illnesses including depression and psychosis. It can produce psychological dependence to the level where cravings occur.

At the present time there is insufficient evidence for its use outside of those applications for which it is legally available. Even it becomes a treatment for depression, this would likely only be under specialist care. Given the potential for harm it would be wrong to argue it is safer than other recreational substances, or to suggest that the behaviour could or should ever be seen as normal.