Nitrous oxide (laughing gas)

Nitrous oxide is a colourless gas that is slightly sweet smelling and tasting. Recreational users normally get it from whipped-cream chargers, which are single-use, finger-length steel cartridges containing 8g of highly pressurised nitrous oxide. These are usually discharged into a balloon with a kind of whipped cream dispenser or a smaller widget called a ‘cracker’. This balloon method seems to be relatively low risk. Nitrous oxide is also found in supermarket cans of whipped cream, although it is not as easily inhalable from this source.

Other sources of nitrous oxide include full sized gas cylinders, intended for medical or industrial use. Using these is high risk outside of the medical context. Breathing the pure gas directly from a tank using a mask on your face may be fatal because it can cause oxygen deprivation. Opening a tank in a car or small room could do the same. Filling a bag with the gas from a tank and putting it over your head can kill easily. Tanks of nitrous oxide intended for use in cars can contain other substances like sulphur dioxide which could cause harm.

The mode of action of nitrous oxide is still unclear. It has been suggested that its general anaesthetic actions are due to blockade of the NMDA subtype of the glutamate receptor and its analgesic actions may come from stimulation of opioid receptors but neither of these are yet proven in humans. The recreational effects occur at lower concentrations and may be produced by alterations in brain blood flow such as are believed responsible for the recreational effects of another gas, nitric oxide, which is produced from the sniffing of “poppers”

When someone inhales nitrous oxide, the gas rapidly dissolves into the bloodstream, and hits the brain within seconds. Effects vary between people and are rarely quite the same twice, but a rush of dizziness and euphoria is normal, and people often burst out laughing. Sound is oddly distorted, voices and music often turning into a throbbing roar like a helicopter.

Hallucinations are possible, from simple moving bright dots to complete detailed dreamscapes, although most users do not experience complex hallucinations. The gas is an anaesthetic, so coordination and awareness are strongly affected and users may fall over if they are not sitting or lying down. The experience ends almost as swiftly as it began, with the peak lasting just seconds and the user back to normal within about 2 minutes. Sometimes, people take many ‘hits’ of nitrous oxide over a few hours. Nitrous oxide also reduces anxiety and pain.

Additionally, when inhaled recreationally in the usual (and least risky) way, from a balloon, the gas in the lungs displaces air, temporarily preventing much or any oxygen getting into the blood. This may cause the heart to beat faster, and limbs to feel tingly or heavy.

Nitrous oxide is used for anaethesia, and relieving pain. It can also help relieve anxiety. It is given to women in labour, in ambulances, emergency departments and in dentistry. The gas used is a typically a mixture of oxygen and nitrous oxide.

If the user of nitrous oxide is in good health, understands the risks, and avoids dangerous methods, nitrous oxide is one of the least risky drugs. However, people have died from oxygen starvation when using unsafe methods to try to breathe large amounts of nitrous oxide for extended periods of time. Inhaling nitrous oxide in a dangerous way will not cause any warning symptoms until the user suddenly becomes unconscious. Then brain damage, followed by death, can occur within minutes.

These risks are unlikely with the common balloon method.

There are hints that using nitrous oxide during pregnancy might pose a risk to the developing foetus (although of course it is used safely during birth). Obstetric nurses exposed to high levels of the gas at work seemed to have more babies with abnormalities, although this possible connection is not yet clearly understood.

Avoidable dangers

1. If used in a risky way, it is easy to starve yourself of oxygen when using nitrous oxide because the reflex that forces you to breathe if you hold your breath does not kick in if you are able to breathe out carbon dioxide. This means if you have your head in a bag of nitrous oxide (even if it is mixed with air) and you are still able to breathe out carbon dioxide freely, your body will be ‘tricked’ into thinking that it is breathing normally. You may feel no discomfort right up to the moment when you black out. Brain damage and death can occur soon after. Because the gas reduces anxiety and coordination before causing unconsciousness, it may be impossible to escape from such a situation even if you realise your mistake.
2. Any attempt to fill a car, room, or bag over your head with nitrous oxide could cause fatal oxygen starvation. Strapping on medicinal gas masks attached to cylinders of pure N2O can also kill (in medical use, masks usually deliver a 50% nitrous oxide, 50% oxygen mix). Importantly, getting some oxygen, but not enough, could still ultimately have the same fatal effect. This means that partially opening a window in a car you intend to fill with nitrous oxide to let the air in may not prevent oxygen starvation.
3. Gas at pressure is dangerous, so care must be taken when filling balloons. Faulty dispensers (especially cheap ‘crackers’), or incorrect use, could cause explosions. When gas is released from pressurised containers, the gas and the metal of the container briefly become intensely cold (-40°C). People have given themselves frostbite of the lips, mouth and even vocal chords through inhaling laughing gas directly from the ‘cracker’, or the nozzle of gas cylinders. Further serious damage could be done to the lungs if the gas came out at high pressure. Dispensing several gas canisters consecutively with one cracker can cause cold burns to hands.
4. There is a risk of falling when taking nitrous oxide whilst standing or dancing. It is safest to get comfortable on a sofa or bed.
5. It has been noticed that some brands of whipped-cream chargers leave an oily residue inside the dispenser, suggesting that they contain some impurities. This has been noted among some chargers imported from China. No specific evidence of harm from this exists, and many people have used the chargers with no reported health problems, but there can be no guarantees of safety when using this product in a way not intended by the manufacturers.

Nitrous oxide could potentially worsen some mental health problems, or trigger a relapse, although there is no specific evidence of this. Additionally, people with heart conditions or abnormal blood pressure may be at higher risk as the drop in oxygen levels caused by inhaling nitrous oxide raises the heart rate and can cause arrhythmias (skipped heartbeats). These are not usually a problem, but could cause cardiac arrests and similar emergencies in susceptible people.

There is no current evidence demonstrating that nitrous oxide used with other drugs increases the risks. However, it is possible that risks could be greater with stimulants and any other drugs that put pressure on your heart, as effects on blood pressure and heart rate could be unpredictable.

Nitrous oxide can, allegedly, briefly multiply the effects of psychedelics like LSD (acid) and psilocybin (magic mushrooms), or bring the effects back strongly when the drug is wearing off, which could be very frightening if unexpected.

Because the effects of nitrous oxide are pleasurable but short-lasting, people are often tempted to take it repeatedly over a short period of time. Very occasionally people become psychologically addicted to nitrous oxide and find it difficult to resist taking it every day. People with mental health issues may be at additional risk of addictive behaviours.

Nitrous oxide is not particularly addictive compared to other drugs, and addictions usually require a combination of a psychological vulnerability (such as low moods or worries that the drug briefly relieves), and easy access to the gas. Stressed dentists and anaesthetists who work with the substance have become addicted. Although addiction is unlikely, if it does occur it can be very harmful.

It has been found that nitrous oxide can be physically and mentally damaging when taken many times each day for long periods as it gradually inactivates the vitamin B12 reserves in the body. Individuals who inhaled large amounts of nitrous oxide daily for long periods have suffered nerve and brain damage because vitamin B12 is essential for the maintenance of a healthy nervous system. The symptoms of such damage vary, and have included severe weakness of the arms and legs in some, and in a handful of cases, episodes of mental illness. Treatment with high doses of B12 is effective, but some damage can be irreversible. It is likely that less severe vitamin B12 deficiencies caused by nitrous oxide overuse go undiagnosed, but cause milder symptoms, such as depression, forgetfulness and tiredness.

Using a balloon

Using a balloon, with caution, is the least risky way to use nitrous oxide. Here the gas is dispensed into a balloon from which a user inhales and exhales repeatedly until they have had enough or the gas runs out. If the user overdoes it and oxygen levels in the body drop to the degree where they are close to passing out, they will be unable to hold the balloon to their lips and will automatically breathe air again. This safety mechanism minimises the risk of death by suffocation, but will not prevent a user overdoing it enough to suffer a headache or other unpleasant effects. Paying attention to any discomfort and not resisting the urge to breathe will minimise the chances of harm of any kind.

Choosing the right setting

The risks of hurting yourself if you fall or lose co-ordination and awareness when taking nitrous oxide can be minimised by sitting down away from hard edges and other hazards.

Never try to fill a space with the gas

If someone has got hold of a large canister of nitrous oxide they should never attempt to fill a room, car, bag over someone’s head, or any enclosed space with the gas. This can lead to fatal oxygen starvation. It is much safer to use a balloon.