Professional Reference articles are written by UK doctors and are based on research evidence, UK and European Guidelines. They are designed for health professionals to use, so you may find the language more technical than the condition leaflets.
Synonyms: street names include 'meth', 'crystal meth', 'ice', 'glass', 'Tina', 'Christine', 'crank', 'tik', 'yaba' and 'crazy medicine'
Methamfetamine (METH) is an amfetamine-type stimulant. Within the central nervous system (CNS), it blocks presynaptic catecholamine reuptake, causing hyperstimulation at the post-synapse. See also separate article Amfetamine Abuse and Intoxication.
It is most commonly smoked in its crystal form ('ice') in a pipe or in aluminium foil, heated by a flame below; however, it can also be snorted, injected, swallowed in pill form ('yaba') or inserted rectally. Smoking the drug increases its bioavailability compared with an oral formulation and decreases plasma half-life. Mean plasma half-life after smoking is about 11 hours. Smoking approaches the bioavailability of injecting. Its effects are compared to those of crack cocaine (euphoria, heightened arousal and increased energy) but longer-lasting due to the longer half-life. It is also highly addictive.
It can be made easily in clandestine home laboratories and is often adulterated with the chemicals used in its synthesis.
Over the 1990s, there was an epidemic of METH use in some parts of America. Whilst amfetamine and ecstasy have been widely used across the UK and Europe, crystal METH use has been and remains to date uncommon, although rates may be increasing. It has been reclassified as a Class A drug so as better to control emergent problems associated with its use.
In the USA, rates of METH use grew steadily over the 1990s but are thought to have stabilised, with 2.8% of 18- to 26-year-olds reporting use. Its popularity spread from Hawaii and California and use is now highest in western and north central states, presenting significant medical and social problems in rural as well as urban populations. METH abuse has spread throughout the world - with high rates in countries such as Thailand, South Africa, Australia, Pacific island states and Mexico.
In the UK, epidemiological data have tended to look at amfetamine and METH use together. However, the 2013/14 Crime Survey for England and Wales asked individuals specifically about METH use. 0.9% of adults aged 16-59 years reported ever using and 0.1% reported use in the previous month.
Abusers typically self-administer the drug in 'runs' of several days, with intervening periods of abstinence. Whilst on a 'run', an individual may stay awake continuously for up to 10 days with little food or drink. Prolonged sleep and mild dysphoria occur as the drug wears off. Immediate subjective effects include:
- Increased alertness.
- Increased energy.
- Increased libido and enhanced sexual pleasure.
- Decreased inhibition.
- Decreased appetite.
- Decreased need for sleep.
Peripheral actions arise due to the indirect sympathomimetic effects of the drug:
- Sweating and hyperthermia.
- Dry mouth.
- Decreased gastrointestinal (GI) motility.
- Dilated pupils.
Central actions may account for some of the other typical behaviours and movement disorders seen such as:
- Jaw clenching.
- Repetitive jerking and choreoathetoid movements.
- Compulsion with repetitive tasks ('punding').
- Formication (sensation of flesh crawling with bugs with associated compulsive picking and infected sores).
Repetitive movements, hyperactivity and difficulty focusing thought are sometimes referred to as 'tweaking'.
- Diarrhoea and nausea.
- Restlessness, agitation and irritability.
- Chest pain due to myocardial infarction or dissecting aortic aneurysm.
- Panic attacks.
- Renal failure.
- Sexually and parenterally transmitted infections.
METH use is associated with high-risk behaviours and serious injury. In one Californian trauma series, METH overtook cannabis as the most common drug used by the trauma population between 2003-2005. Use of METH increased the risk of:
- A violent mechanism of injury.
- Gun and stab wounds.
- Attempted suicide.
- Domestic violence.
- Death from injuries.
Aside from the risks associated with the use of METH, there are hazards associated with the production of METH and toxic waste exposure. Those indirectly involved (neighbours, family members, children and emergency personnel) as well as users and producers may present with:
- Serious burns due to explosions (METH laboratories explode due to volatile substances used in production).
- Symptoms of environmental exposure (eg, headache, nausea, dizziness, dyspnoea and eye irritation).
- Heavy metal poisoning.
The differential is wide and includes:
- Hypertensive crisis.
- Toxicity from other stimulant/sympathomimetic/hallucinogen.
Be aware that many patients will not only have used METH - polydrug use (including alcohol) is the norm, so consider whether there is a mixed picture.
- Diagnostic testing:
- Urine - METH is detectable for 48 hours after use.
- Hair analysis.
- Meconium testing - the most accurate method in neonates.
- Other laboratory tests should be directed towards symptoms:
- Blood tests - FBC, U&Es, creatine kinase (CK), cardiac enzymes.
- CXR - where there are pulmonary symptoms.
- CT scan - where there is altered mental status.
- Sexual health promotion - offer sexually transmitted infection (STI) and pregnancy testing.
- Consider staff safety - patients may be highly agitated and unpredictable. Call for security/police back-up where necessary. Sedation with neuroleptics (eg, haloperidol) may be required.
- Management is largely supportive.
- Activated charcoal is only helpful where there has been oral ingestion.
- Benzodiazepines are indicated for seizures.
- Cooling measures may be necessary where there is hyperthermia.
- Treatment of hypertension may require intravenous beta-blockers.
- The use of olanzapine and risperidone to treat amfetamine-related psychosis is also under investigation.
- Before discharge, consider additional needs and referrals. For example, drug and alcohol team, psychiatry, social services (consider child protection issues) and genitourinary medicine (GUM) clinic.
- Symptoms include:
- Problems with concentrating
- Psychomotor slowing
- Increased appetite
- Withdrawal from stimulants is considered less dangerous than from alcohol, opioids or sedatives; however, seizures are possible.
- Compared with cocaine withdrawal, METH withdrawal is considered to produce more severe and prolonged depression so careful monitoring for suicidal ideation is important.
Treatment of abuse and dependence
- There is no effective treatment currently. Research into pharmacological treatment for METH dependence is ongoing - candidate drugs have included bupropion, mirtazapine, baclofen and topiramate.However, medication is considered primarily an adjunct to the use of psychosocial interventions.
- Outpatient behavioural therapies are the standard treatment currently in the USA. The use of cognitive behavioural therapy and contingency management have been borrowed from the treatment of cocaine addiction and applied to METH and have been shown to be effective in reducing use in the short-term, although longevity has yet to be proven. Contingency management gives rewards to patients who provide drug-free urine specimens although recent research suggests this effect may last as little as 6 months.
- Support groups and 12-step treatment programmes may also offer benefit.
For METH users
The morbidity associated with METH use is considerable:
- Myocardial infarction, dissecting aortic aneurysm, cardiomyopathy.
- Hypertensive crises and stroke.
- Rhabdomyolysis and kidney failure.
- 'Crystal cock' (erectile dysfunction).
- GI ulcers and ischaemic colitis.
- Pulmonary hypertension.
- Skin abscesses and lesions.
- Premature ageing.
- Cognitive impairment - confusion, memory loss, motor slowing and learning impairment.
- 'Meth mouth' (dental decay).[17, 18]
- Psychiatric disorders:
- Suicidal ideation and behaviour,
- Malnutrition and weight loss.
- Dependence and withdrawal-related symptoms.
- Trauma-related injuries.
- Placental insufficiency and abruption.
- Intrauterine growth restriction.
- Cleft palate defects.
- Cardiac anomalies.
- Miscarriage and stillbirth.
For children of METH users
- Neonatal withdrawal (usually milder than with opiate withdrawal) - abnormal sleep, poor feeding, decreased movement and arousal, increased stress response.
- Long-term effects of intrauterine exposure are unclear - possible developmental delay.
- Neglect and abuse.
- Inadvertent poisoning and trauma.
Public health issues
- Environmental health risk from illicit laboratories and illegal toxic waste.
- Increased rate of STI transmission - in particular, HIV.
- Increased levels of crime and violence.
METH use is associated with rapid dependence and sharp physical decline, often accompanied by criminality. Cases of acute uncomplicated toxicity treated rapidly and appropriately have a good prognosis but outcome associated with chronic use is much less positive. Relapse rates following treatment for dependence are high (one study suggesting 36% under 6 months and a further 15% between 7-19 months). Anecdotal evidence in areas with high METH use suggests significant drug-related death rates, either direct (related to toxicity) or more often indirect (eg, road traffic accidents, homicide, suicide).
Efforts in North America have centred around education (including high-profile, 'shock' advertisements), targeted interventions to those considered high-risk (eg, pregnant women users) and law enforcement strategies such as limiting the availability of precursor substances - for example, pseudoephedrine (found in cold remedies and decongestants). This has limited success at the expense of limiting access to the public to effective medicines.
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Further reading & references
- Drugfucked; Terrence Higgins Trust
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