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the molecular structure of methamphetamine
  • Methamphetamine is a stimulant drug of the substituted amphetamine class. The addition of a methyl group gives the drug high lipid solubility, leading to it being more potent and euphoric than amphetamine. Methamphetamine is also known for its long-lasting effects and is considered to have very high abuse potential.

    Methamphetamine was first synthesised in 1887 but did not have any known medical use until 1934. It was initially sold as a decongestant. It is now used primarily for treating treatment resistant obesity and ADHD, though it is not used medically in the UK. Methamphetamine was reclassified from class B to class A in 2007, due to fears of increasing prevalence of use.

    Other common names include: meth, tina, shard, crystal and ice, among others.

  • Methamphetamine comes in a variety of forms and can differ in purity from batch to batch.


    Crystal methamphetamine

    This is the most common form of illicit methamphetamine seen on the street. It generally appears as medium sized glass-like crystals. It can also look like white/clear crystal powder, and coloured crystals have been reported – though these tend to be artificially coloured using food dye. It can be taken orally (rolled up in cigarette paper and swallowed), snorted, rubbed on the gums, smoked or dissolved in water and injected (both intramuscular and intravenous injection). Smoking and injection are the most likely to result in addiction, as they quickly produce a ‘rush’ of euphoria, though all routes of administration can lead to addiction. Smoking/vaporisation and injection are the most dangerous methods of using the substance, as the euphoria can fade much faster than the other effects of the drug wear off. This can lead to compulsive redosing, amplifying the longer lasting effects.


    Methamphetamine freebase

    Freebase methamphetamine appears without the associated hydrochloride molecule of the salt form (methamphetamine HCL), just like the difference between cocaine powder (cocaine HCL) and crack cocaine (freebase cocaine).

    At room temperature, freebase methamphetamine is a colourless liquid.


    Methamphetamine pills

    Illicitly produced methamphetamine pills are relatively unlikely to be sold openly advertised as methamphetamine. People who knowingly choose to use methamphetamine tend to be looking for crystal meth, as it allows the drug to be injected or smoked more easily. Sometimes pills sold as MDMA, or other substances, may contain methamphetamine as either the only active ingredient, or one of multiple active ingredients, though this is relatively rare in the UK.


    Prescription methamphetamine

    Prescription methamphetamine, known as Desoxyn, is manufactured in 5 mg pills. It is not routinely prescribed by the NHS, but may be for cases of ADHD in which methylphenidate (Ritalin), dextroamphetamine and lisdexamphetamine (an amphetamine prodrug) have been unsuccessful. It can be prescribed in America for extreme cases of ADHD and obesity, but is not licensed for use in the UK.

  • Methamphetamine is a psychostimulant. This means that it works by increasing activity in certain parts of the nervous system. Specifically, it acts as a releasing agent for serotonin, dopamine and noradrenaline. It also inhibits the reuptake of noradrenaline meaning any released stays in the brain for longer than it otherwise would. These changes increase the levels of extracellular monoamine neurotransmitters. Methamphetamine is an analogue of amphetamine, where the addition of the methyl group increases the solubility in lipids. This allows it to cross the blood brain barrier much faster – leading to greater euphoric effects and faster onset of action compared to amphetamine.

  • When swallowed, methamphetamine’s effects usually take under an hour to kick in, with the full effects taking up to four hours to develop – though this can be as little as an hour on an empty stomach. This time can be extended further after a particularly large meal. After snorting, methamphetamine usually kicks in after just a few minutes, and smoking or injecting can have effects within seconds.


    Methamphetamine exhibits its full effects faster when smoked than injected, as the pulmonary blood is pumped to the brain faster than venous blood. The effects can typically last up to 12 hours when taken orally, and up to 8 hours by other routes of administration. It is worth noting that for naïve/first-time users the effects of methamphetamine can last for up to twice as long as these figures – for oral administration the effects can last as long as 24 hours. The effects of methamphetamine can last for several days, especially if repeat doses are used even if the total use spans a relatively short time frame. Tolerance can build quickly, causing people to use increasingly large amounts of the drug. Repeated high dose administration has been linked to rapid reduction of striatal dopamine transporter activity.


    Often psychological effects of methamphetamine are similar to amphetamine and other dopaminergic stimulants, though generally far more intense and longer lasting. These similarities include marked increases in alertness, sociability and confidence (users often find themselves becoming very chatty), focus/motivation and euphoria. Other effects include the impression of time compression, thought acceleration and organisation and analysis enhancement. When the drug is injected or smoked this euphoric rush can be very intense, but can fade long before the stimulating and physical effects of the methamphetamine fully wears off. This can lead to compulsive redosing, compounding the physical effects of the drug.


    The energising effects of methamphetamine can decrease feelings of tiredness. This is why it has sometimes been used by people who want to continue physical activities, like dancing, for long periods of time. Methamphetamine may be used in ‘chemsex’ scenes for the reduced tiredness, as well as enhancement of sexual pleasure and increased libido. Meth has been used by professionals and students, to help them work for longer periods of time. Use in these situations is generally uncommon in the UK as users will often opt for other stimulants such as amphetamine or methylphenidate (Ritalin). Places where the drug is prevalent usually have limited access to other stimulant drugs, leading to people only having access to methamphetamine. In the UK, methamphetamine is rarely used as people have ready access to more typical stimulants. Common examples include MDMA, amphetamine sulphate and mephedrone. The emergence of new psychoactive compounds may play a role in reducing the use of some more common drugs.


    Reported undesirable effects of meth include paranoia, violence/aggression and short temper, irritability and anxiety. Psychotic symptoms, resembling those associated with schizophrenia, can occur when using methamphetamine. These can include paranoid thoughts, or even delusions. These thoughts and delusions can consist of the belief that people are spying on you or recording your movements, or believing that you are being targeted for a crime such as a robbery. Hallucinations can occur, including hearing music that isn’t there or hearing people talking about you. With methamphetamine, owing to the more powerful and longer lasting nature of the drug, the hallucinations can include seeing shadow people, either in one’s peripheral vision or, in extreme cases, fully formed in focus. Psychotic symptoms may happen during methamphetamine intoxication and can last for days or weeks after the intoxication phase of drug use.


    Physical effects of methamphetamine include: increased heart rate and constriction of blood vessels (higher blood pressure), increased energy, ‘physical euphoria (often described as a pleasant tingling sensation), dilated pupils, appetite reduction, dry mouth and a rise in body temperature.


    The after effects, or ‘come down’ from methamphetamine can last for several days following drug taking and can be described as a rebound from the ‘high’, though less intense than withdrawal symptoms. People often feel muddled, irritable, socially incapable, depressed, tired and anxious. People may also experience an inability to sleep (insomnia), restlessness, twitching, muscle aches and both perceived and physical fluctuations in temperature. At high doses, this ‘come down’ can be severe – involving vomiting, diarrhoea and psychotic episodes similar to those that occur in schizophrenia.

  • Methamphetamine, produced under the brand name Desoxyn, can be used to treat many of the same conditions medical amphetamine is used for. In America Desoxyn is prescribed, in 5mg doses, to treat obesity and ADHD in cases where people have not responded to other forms of treatment. Due to its potential for abuse it is licensed as a last resort only, and is not routinely prescribed.

    Methamphetamine may have potential uses in treating depression, in particular for those who have low mood and lack of motivation as a result of depression. However, conventional antidepressants, or even other amphetamines, are almost always more appropriate.

    Due to methamphetamine’s high potential for abuse and lack of clear benefits over amphetamine to outweigh this, methamphetamine is not a prescription drug in the UK.

  • Fatal overdoses from methamphetamine use occur more frequently than for other stimulants such as amphetamine sulphate, with 15,489 deaths associated with methamphetamine use in America in 2019. This is generally due to methamphetamine induced heart attacks or strokes resulting from the rise in blood pressure and constriction of blood vessels. Methamphetamine also causes a marked increase in serotonin, and high doses can lead to serotonin syndrome. This causes overheating and high blood pressure. People with pre-existing heart problems, and people at increased risk of heart disease and strokes, are more likely to experience such complications from taking methamphetamine.

    Higher doses of methamphetamine can induce stimulant psychosis, presenting as paranoia, delusions and hallucinations. Some people have become violent, harming themselves and/or others in states of methamphetamine induced psychosis. Lack of sleep from repeated doses can increase the risk of symptoms. Some people who experience symptoms of psychosis do not fully recover, experiencing lasting symptoms. People taking methamphetamine with a history, or family history, of mental health problems are more likely to experience methamphetamine related mental health problems.

    Some people may inject methamphetamine, which carries much higher risk. This includes the chance of getting HIV, hepatitis or bacterial infections, as well as increased risk of addiction to the drug. If you choose to inject despite the increased risk, this can be reduced by using new needles and injecting equipment. You can get these from needle exchanges, which may be found in pharmacies or hospitals.

  • Yes. Methamphetamine is potentially more risky for people who have pre-existing heart conditions, or who have or are at risk of circulation problems including high blood pressure.


    Methamphetamine can worsen glaucoma due to the changes it can have on blood pressure.


    Methamphetamine may be riskier for people with mental health problems. People with schizophrenia (or family history), or a history of psychosis should avoid using methamphetamine as they tend to be much more sensitive to experiencing psychotic side-effects. This could trigger a relapse of psychosis or schizophrenia.

  • Taking methamphetamine with other stimulants can result in very high heart rate, blood pressure and body temperature. Methamphetamine may mask the early warning signs of depressant drugs such as alcohol or opioids. This can lead to people taking more than they otherwise would, increasing the risk of overdose from the depressant drug.


    Methamphetamine can be very dangerous if you are currently taking a monoamine oxidase inhibitor (MAOI) antidepressant, as both increase extracellular serotonin and can lead to serotonin syndrome when used together.  The analgesic opioid tramadol can increase the risk of seizures when combined with methamphetamine, as the isomers of tramadol increase the extracellular levels of 5-HT and noradrenaline through reuptake inhibition, so the two should not be mixed. Mixing with tramadol may also increase the risk of damage to the heart and of psychosis.

  • Methamphetamine is considered to have an extremely high potential for abuse. Using methamphetamine regularly is likely to lead to both physical dependence and psychological addiction to the drug. Methamphetamine use can become increasingly compulsive and out of control, with many users experiencing withdrawal symptoms when not taking the drug. Withdrawal symptoms are generally a rebound from the effects of the drug. Methamphetamine withdrawals typically include a strong ‘crash’, anxiety, fatigue and lethargy, vivid/lucid dreams, cravings for the drug, insomnia and depression.

  • Long term use of methamphetamine can cause significant harm and seriously impact quality of life.


    Long term use of methamphetamine at moderate to high dosage is considered to be highly neurotoxic. Long term use can damage the heart and result in an irregular heart-beat, a form of cardiotoxicity. Long term use can result in anhedonia; a general difficulty in finding pleasure in life without the drug, which can lead to increased difficulty in quitting the drug. It is difficult to establish to what extent anhedonia is a contributing factor to addiction, but the risk of this resulting from heavy sustained use should be taken very seriously. Some of the long-term side effects of use such as malnutrition and cancer may be linked to adulterants in supply on the street, as well as poverty and a chaotic lifestyle that can result from addiction.


    Methamphetamine dependence can often cause people to suffer serious sleep problems, poor nutrition and extreme weight-loss (due to the reduction in hunger), which can cause an accelerated appearance of aging.


    Methamphetamine can lead to gum disease and damage to peoples’ teeth caused by the ‘dry mouth’ effect, where people on the drug are not producing enough saliva to protect their mouth. This is frequently portrayed in the media, though often exaggerated. Gum disease should be recognised as a side effect from consuming methamphetamine – and not only when smoking the drug.

  • Be careful what, and how much, you are taking

    Methamphetamine can often be taken accidentally due to being mis sold as another drug in areas where it is a larger part of the drug scene (such as America and Australia), which can be a very stressful experience. Many users are concerned by the high levels of stigma towards the drug, as well as the very long duration of action compared to most stimulants. The duration can lead to a higher chance of something going wrong, extend any uncomfortable and unwanted effects, as well as cause further disruption to one’s day/night. If you are worried that you have consumed methamphetamine by accident, you should stay cool and hydrated, as well as ensuring that you are not alone. It can be very important to have someone to help you during the experience, and judge if medical care is needed. Medical care should be sought if you are experiencing chest pains or tunnel vision, or are becoming a danger to yourself or others.


    Methamphetamine purity can vary by batch. In 2019, methamphetamine in the UK varied in content from 12% to 87%, with an average (mean) purity of 79%. The current strength in the UK is not known, but in 2022 methamphetamine in France had purity between 77 and 100%. This is a large variation in strength, so users should be careful not to inadvertently take more than required for the desired effects. Unlike methamphetamine found in Australia or America, in the UK (and Europe) it is generally produced in high-tech Dutch labs. This means that it is more likely to be isolated as the more active dextro-isomer. Just like for amphetamine, this form of methamphetamine is considered to be stronger than mixtures of the dextro and levo isomeric forms, which users should bear in mind. Methamphetamine can be cut with dangerous and toxic fillers, and other psychoactive drugs.


    It is always a good idea to start with a low dose and work up to a comfortable and satisfactory dose. Even if the methamphetamine is pure, higher doses carry greater risks.


    Injecting drugs tends to be much more harmful

    It is much easier to take too much when injecting the drug. Although the doses are not significantly different hen comparing routes of administration, the rush created upon administration is much more intense when injecting the drug, which can be overwhelming for some people, and puts greater strain on the body. Injection is also associated with a range of other risks, including infection, damage to the veins and increased risk of addiction.


    Tolerance is a warning sign

    Increasing tolerance to a drug is an early sign that the body and brain are changing in response to the drug. Tolerance, the need to administer increasingly larger amounts of a drug to obtain the same effect, is a sign of lingering changes in brain chemistry. This can often be a sign that use is transitioning from recreational use to becoming dependant. Methamphetamine will exhibit cross-tolerance with all dopaminergic stimulants (such as amphetamine, methylphenidate and cocaine).


    If you experience tolerance developing to stimulant drugs, it may be a good idea to reassess your use and consider taking a break.

  • Methamphetamine dependence can happen from just one use

    Forming a physical dependence, such that withdrawal symptoms appear when you don’t take the drug, requires repeated uses in a short space of time. However, some users feel that they ‘fell in love’ with the drug (craving its effects) from their first experience with it, as it can be immediately pleasurable. Methamphetamine can give the user seemingly unlimited energy and motivation, and having experienced it once, the temptation to use again may arise the next time a person feels in need of the effects.


    It is also worth noting that the rebound effects from methamphetamine may be confused with withdrawal effects and therefore physical dependence.


    Methamphetamine destroys people’s faces and causes dental decay

    Whilst long-term use of methamphetamine can accelerate aging and contribute to gum decay, the images portrayed in the media are often exaggerated. The term “meth mouth” originated from a report by the Academy of General Dentistry, a report not corroborated by any supporting data or research, but rather a series of case studies about amphetamine related dental disease.


    The cause of methamphetamine related dental disease/decay is often reported in the media and pop-culture as resulting from smoking the drug. Whilst the exact causes are not fully understood, and cutting agents found in meth may damage the gums when smoked, the primary causes of dental decay are believed to be dry mouth, increased consumption of sugary foods and drinks, grinding one’s teeth together and infrequent oral hygiene.


    The symptoms can be mitigated through ensuring good oral hygiene, limiting the consumption of sugary drinks (although, they can be a reliable and accessible energy source when it is not possible to eat) and chewing sugar-free gum (chewing gum helps to reduce the damage done when grinding teeth and stimulates saliva release).


    Methamphetamine must be smoked or injected

    Methamphetamine in the media often focusses on smoking/injection of the drug. Whilst most users do smoke methamphetamine, it can be taken orally and by snorting the drug as well, which can reduce the range of harms associated with use.


    Methamphetamine can be used to improve performance in school, work or sports

    Stimulants are often used in the treatment of ADHD, and can give non-affected people the feeling/perception that they are more motivated and/or performing better. In reality, academic performance and concentration aren’t improved by stimulants like methamphetamine, and in some cases (such as in associative learning) can even worsen people’s results.


    Stimulants do prove more effective when used to improve sports performance, such as endurance and strength, but strenuous exercise can greatly increase the risk of dangerous side-effects associated with stimulant use.

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