Solvents

Description

Solvents are gases, glues or aerosols that are inhaled. They vary from normal household products to petrol and laughing gas. They slow down the body’s responses (depressant). Many household and industrial products contain chemicals that, when inhaled, can cause intoxication. These products are referred to as volatile substances or solvents. Examples are toluene, butane and other volatile hydrocarbons that evaporate at room temperature.

Products that may contain solvents include aerosols (e.g. air fresheners, hair sprays and deodorants), some paints and paint thinners, petrol, some correction fluids, nail varnish removers, some glues and cigarette gas-lighter refills.

Physical co-ordination may be impaired. Users may feel light-headed, dizzy or drowsy. Altered perception may be experienced, ranging from visual distortion to auditory and visual hallucination.

Effects vary from user to user and according to the type and quantity of substance used.

Pharmacology

Most solvents used recreationally are central nervous system depressants: this means they slow down operation in certain areas of the brain. This is typically by potentiating GABA-A and inhibiting NMDA glutamate receptor activity, similar in mechanism to other depressant drugs. Volatile nitrites (amyl nitrite, butyl nitrite and isobutyl nitrite) dilate blood vessels and cause a brief drop in blood pressure. Volatile nitrates (poppers) therefor work quite differently and have distinct risks and harms and should not be treated the same as CNS depressant solvents.

For volatile solvents and hydrocarbon gases (butane/propane etc), a meaningful part of the high is a direct result of reduced oxygen reaching the brain as a self induced asphyxia rather than receptor effect alone. In practice this has significant impact on harm reduction messaging. Unlike with most other drugs the recreational effects and the toxic/lethal effects are produced by overlapping mechanisms rather than sitting on separate parts of a dose curve. This means there is no clear “moderate use” tier that avoids the harms. When used excessively, this can result in unconsciousness and permanent brain damage.

When inhaled, solvents enter the bloodstream directly from the lungs and rapidly reach the brain and other organs. Some are broken down and excreted through the kidneys, ultimately being passed out in urine; however others are exhaled unchanged through the lungs. As a result, it is sometimes possible to smell the original solvent on the breath of the user for several hours following use.

Butane and propane in particular sensitise the heart to circulating adrenaline, so sudden startling, exertion or even anxiety during or shortly after use can trigger fatal arrhythmias. This is the mechanism behind “sudden sniffing death” and isn't reliably dose dependent. It has been recorded in first time low exposure users.

Chronic heavy exposure particularly with toluene containing solvents is linked to demyelination (the loss of the sheath around nerve fibres which speed up signalling). This can cause white matter loss, affecting processing speed, coordination and memory. This cumulative damage is separate from and additional to the acute hypoxic and cardiac risks.

Solvents are not typically physically addictive in the way opioids or alcohol are, though tolerance can develop with regular use and some psychological dependence has been reported. Users may feel they can't do without them for a period after stopping; these cravings generally lessen with time. Mild withdrawal symptoms (anxiety, irritability, headaches) have been reported in regular users.

Harm Reduction

• Side effects vary according to the user and the substance and quantity used. It may include headaches, nausea and soreness of the throat. Extended use may cause unconsciousness.
• Some other warning signs will include weight loss/gain, memory problems, respiratory problems, depression, displays of aggression and paranoia, anxiety and frustration. This cluster of psychiatric difficulties can lead to self harming and suicidal ideation. This is clearly a situation that requires professional help. Contact your local GP, specialist service or Release.
• Solvent use represents a significant cause of death or injury among young people. In 1999, 75 people died as a result of volatile substances use. Causes of death or injury include:
• Heart failure – solvent use may stop the heart instantly or cause it to beat irregularly. Sudden exercise after inhaling solvents increases the risk of heart failure.
• Suffocation and asphyxiation – spraying aerosols or butane gas down the throat can cause swelling of the windpipe, leading to asphyxiation. When volatile substances are used in an enclosed space, there is a risk of suffocation due to lack of oxygen, especially if the user becomes unconscious. When users place their whole head in a bag containing a volatile substance, they incur a high risk of suffocation. Choking on vomit, especially when unconscious, is another significant risk.
• Accidental injuries – users may become confused and disorientated. This creates a risk of accidents such as falling or drowning. Young people may use volatile substances in dangerous environments such as car parks, construction sites, railway embankments or river sides. Such places are hazardous and may be inaccessible to emergency services.
• Burns – solvents can usually be highly flammable and therefore carry a high risk of serious burn injuries, especially when used near cigarettes or candles.
• Cold Injury- spraying gas directly onto skin or into the mouth can cause frostbite type burns from rapid cooling.
• Avoid use alone- If someone loses consciousness, theres no one to put them in the recovery position or get help.
• Avoid confined, unventilated spaces and never put your whole head inside a bag.
• Never spray gas or aerosol directly into the mouth or throat.
• Avoid any exertion, sudden movement, or being startled during or shortly after use.
• Don't combine with alcohol or other depressants — respiratory depression is additive.
• Sit down or lean against something rather than standing.
• If someone is unresponsive after use: recovery position, check airway and breathing, call 999 — this is a medical emergency.

History

Solvents have been known and used as fuel, medicines, and cosmetics as well as for many other purposes since ancient times. The burning of herbs and spices to produce vapours is arguably one of the earliest uses of substances as inhalants. The Industrial Revolution made both their usefulness and reproduction much more widespread; ‘inhalant parties’ were popular in the 19th century, and the use of ‘laughing gas’ (nitrous oxide) was even famously promoted as an ‘entertainment’ to massed audiences. Soldiers fighting in the First World War are known to have used petrol as an inhalant to distract them from the horrors of the conflict.

Modern use of commercially produced solvents (sometimes referred to in the media as ‘glue sniffing’, even though it can in fact involve a number of substances) dates back to at least the 1950s, but there are few records of it in the UK before the 1960s. Perhaps the most famous period/subculture to have embraced them was the punk movement; in fact, one of the most influential fanzines was called ‘Sniffin’ Glue’ (1976-77), the title coming from a Ramones song.

Today, largely due to the widespread availability of the substances involved, recreational solvent use is mostly associated with teenagers who are too young to purchase legal forms of intoxication (such as alcohol) and find it difficult to access other substances. Various laws have been introduced since the mid-1980s to raise the age at which it is legal to purchase many solvent-containing products in an attempt to cut off this route of access for young people.

Law

• General solvents (glue, aerosols, butane, petrol, etc.): still not controlled under the Misuse of Drugs Act 1971. Possession by an adult remains legal. The Intoxicating Substances (Supply) Act 1985 (which made under-18 supply an offence) was repealed in May 2016, but the gap was filled, not left open: general volatile-substance supply is now covered by the Psychoactive Substances Act 2016. Under that Act, it's an offence to supply (or offer to supply) a substance, of any age of purchaser, not just under-18s. If the seller knows, or is reckless as to whether, it's likely to be inhaled for its psychoactive effect. Maximum sentence on indictment is 7 years, an unlimited fine, or both; there's no possession offence outside custodial institutions. The Cigarette Lighter Refill (Safety) Regulations 1999 additionally make it a specific offence to supply butane lighter refill canisters to under-18s.
• Nitrous oxide is now a distinct case: unlike other solvents/gases, nitrous oxide was pulled out of the Psychoactive Substances Act framework and reclassified as a Class C drug under the Misuse of Drugs Act 1971, effective 8 November 2023. This is a significant divergence from the rest of this category. Simple possession of NOS is now a criminal offence in its own right (up to 2 years' imprisonment), where possession of other solvents/gases still isn't. Supply/production carries up to 14 years. Legitimate uses (medical, catering, industrial) remain exempt via Schedule 5 status, provided there's no intent for it to be wrongly inhaled.
• Alkyl nitrites ("poppers"): unlike nitrous oxide, alkyl nitrites have never been brought under the Misuse of Drugs Act 1971, and their status under the Psychoactive Substances Act 2016 is unsettled rather than simply "legal." When the PSA 2016 was debated, concern was raised, including from MPs who used poppers themselves, that its blanket definition of a "psychoactive substance" would catch them, given their popularity as a sexual aid among gay and bisexual men. The government asked the ACMD to rule on it, and in March 2016 the ACMD advised that alkyl nitrites act peripherally on smooth muscle rather than directly on the central nervous system, so fall outside the Act's definition; the government accepted this, and poppers were not added to the Act's list of exempted substances because it was judged unnecessary. That position was complicated by a 2017/18 Court of Appeal ruling on nitrous oxide, which broadened "psychoactive effect" to include substances acting indirectly, reopening the question of whether poppers could, after all, be caught by the PSA. The government subsequently asked the ACMD to look again, and in a May 2024 report the ACMD recommended alkyl nitrites be formally exempted by adding them to Schedule 1 of the Act. That exemption hasn't yet been legislated, so poppers currently sit in a genuine grey zone: openly and legally sold across the UK (typically marketed as room aromas or leather cleaner rather than for inhalation), with no prosecutions in practice, but without a clean statutory guarantee that supply is lawful. As with other solvents, simple possession has never been an offence.