Amphetamine abuse and intoxication

Synonyms: street names for amphetamines include 'speed', 'sulphate', 'whizz', 'billy', 'dexys', 'base'. Street names for methamphetamine include 'meth', 'ice', 'crystal', 'crank', 'glass', 'tina', 'yaba'

See related separate article Crystal Methamphetamine Drug Abuse.

What are amphetamines?

Amphetamines are commonly-abused drugs internationally, with approximately 34 million users worldwide. Rates of amphetamine abuse vary significantly, and are highest in the USA and Australia.¹

Amphetamines have central and peripheral sympathomimetic action and are powerful and addictive stimulants. They are relatively easily manufactured in numerous illegal laboratories and are readily available on the streets, varying considerably in purity and potency.

Khat is the only known organically derived amphetamine and is extracted from the leaves of the Qat tree found in East Africa and the Arabian Peninsula.

Amphetamines may be snorted, smoked, injected or ingested, and even small doses may exert a profound effect. Depending on the method of administration the user may experience an intense 'rush' or a prolonged 'high'.

Both effects are thought to be due to the release of high levels of dopamine into the pleasure-regulating areas of the brain. Chronic users develop a tolerance and dose levels may escalate. This appears to be particularly true of methamphetamine.

They were used legally between the 1930s and 1960s, with mainstream prescribing for multiple medical uses.² Current limited indications include:

• Attention deficit hyperactivity disorder (ADHD).

• Narcolepsy.

• Exceptionally, for depression.

They should no longer be used for weight loss.

Stimulants are increasingly prescribed for ADHD, as diagnosed ADHD rates increase.³ In the UK, methylphenidate, dexamfetamine, and lisdexamfetamine are all licensed amphetamine treatments for ADHD. They also have recreational value and may be diverted and re-sold. Amphetamine use for 'cognitive enhancement', particularly in university students, appears to be relatively common, especially in the US, with estimates of non-prescription stimulant use as high as 35% amongst university students.⁴

In the UK, methamphetamine is a Class A drug. Other amphetamines are Class B drugs, unless they are prepared for injection, in which case they are considered Class A drugs.⁵

How common is amphetamine use? (epidemiology)

The 2022 Crime Survey for England and Wales estimated that 0.3% of 16-54 year olds and 0.8% of 16-24 year olds had used amphetamines at least once in the past year. This figure has fallen over time; the corresponding estimate for 16-24 year olds in 1995 was 11.7%.⁶

Amphetamine abuse symptoms (presentation)⁷

The effects of amphetamine abuse can be divided into immediate, long-term and withdrawal effects.

Immediate effects

• Euphoria - a 'rush' or 'high'.

• Rapid and/or irregular heartbeat.

• Increase in blood pressure.

• Increase in body temperature.

• Increase in respiratory rate.

• Increased wakefulness.

• Agitation.

• Convulsions.

• Tremor.

• Disinhibition.

• Nausea and vomiting, dry mouth, diarrhoea.

• Damage to nerve endings in dopamine-containing areas of the brain.

• Anorexia.

Long-term effects

• Addiction.

• Violent behaviour.

• Anxiety.

• Confusion.

• Visual, sensory and auditory hallucinations.

• Mood disturbance.

• Weight loss.

• Repetitive motor activity.

• Formication (sensory hallucination of insects crawling on/under skin, leading to obsessive scratching) and ulceration.

Withdrawal effects⁸

Amphetamine withdrawal severity declines from an initial peak within 24 hours of last use, to near control levels by the end of the first week. This acute phase of withdrawal is characterised by:

• Increased eating.

• Fatigue and increased sleeping.

• Depression.

• Paranoia.

• Anxiety and craving-related symptoms.

• Suicidality.

Differential diagnosis

• Abuse of other stimulants such as cocaine.

• Hyperthyroidism.

• Psychotic illness, eg, schizophrenia, mania.

• Alcohol withdrawal.

Assessment and investigations⁷

When assessing a person with suspected acute amphetamine toxicity:

• Ask about which amphetamines were taken, the method of ingestion, quantity, time of exposure, and the place of exposure (for example, consumption in crowded nightclubs with high ambient temperatures increases the risk of hyperthermia and metabolic disturbances).

• Enquire about symptoms suggestive of specific complications, eg, chest pain, palpitations, focal neurological symptoms, and headaches.

• Enquire about any other drugs that were co-ingested.

• Perform a focused examination; directed by the presenting complaint, if available. If there is more significant toxicity (for example, if the patient has altered consciousness), a structured examination should look for signs of life-threatening cardiovascular, autonomic, metabolic and neurological complications.

• Investigations depend on the history and examination findings: for example, electrolytes, renal and liver function, creatine kinase (to exclude rhabdomyolysis which may complicate overdose), ECG, CXR, and neurological imaging.

• Urine drug amphetamine tests are poorly-sensitive. In addition, a positive amphetamine drug screen does not necessarily mean that the immediate presentation is due to amphetamine toxicity; amphetamine drug screens remain positive for about 48 hours after use. Amphetamine drug screens are of very limited utility for emergency clinical management, but may have a role in medico-legal circumstances, such as in child protection proceedings.

Amphetamine overdose treatment⁷

There is no specific treatment available for amphetamine overdose or intoxication, and both immediate and long-term management is symptomatic and supportive.

Immediate management

Any of the following may be of use in the immediate management of amphetamine toxicity, depending on the severity of the presenting condition:

• Observation in a safe quiet environment.

• Benzodiazepines (although beware development of co-dependency on these for 'come-down').

• Anticonvulsants.

• Ice baths to reduce temperature.

Amphetamine withdrawal symptoms⁸

Withdrawal is common amongst regular amphetamine users (reported prevalence of 87%) with intense and prolonged cravings being dominant symptoms. There is very little evidence regarding the appropriate management, whether psychological or biological.

A 2009 Cochrane review concluded that no medication is effective for treatment of amphetamine withdrawal. Amineptine improved discontinuation rates but had no effect on reducing withdrawal symptoms or craving.

It is not used in clinical practice due to concerns regarding the potential for abuse of the drug. Mirtazapine showed benefits in withdrawal symptoms over placebo in one randomised controlled trial, but no benefit in another.

There is a very limited evidence base for the treatment of amphetamine psychosis but antipsychotic medication is thought to be effective in reducing symptoms.⁹

Long-term treatment

People with amphetamine addiction, and perhaps their families, will require long-term support, and several specialist agencies exist which are able to provide assistance (see web links below).

The first port of call is the local Drug Treatment Centre for any user who has asked for help or is prepared to receive help. Harm reduction and general medical services are important and specific treatment strategies may include:

• Cognitive and behavioural therapies.¹⁰

• Antidepressant drugs (Note: very limited evidence of benefit of tricyclics or selective serotonin reuptake inhibitors (SSRIs).¹¹

• Neuroleptic drugs.

Complications¹²

• Stroke (due to hypertensive crisis or vasospasm).¹³

• Myocardial infarction.¹⁴

• Pulmonary oedema.

• Trauma due to intoxication.

• Lead and other chemical poisoning from exposure to chemicals used in drug production.

• Complications of intravenous (IV) use (eg, cellulitis, phlebitis, vasculitis, bacterial endocarditis, infections spread by equipment sharing).

• Neglect and abuse of dependent children.

• Use in pregnancy associated with high risk of premature delivery and low birthweight.¹⁵

• Drug-induced psychosis.

• Anxiety, depression and increased risk of suicide.

• Cognitive impairment with long-term use.

• High-risk sexual behaviour.

  • Recreational methamphetamine use amongst men who have sex with men is associated with a higher rate of high-risk sexual behaviour and HIV transmission.¹⁶

An Australian study showed that amphetamine use before the age of 17 was associated with increased risk of a range of other substance abuse, worse psychological morbidity and social problems in early adulthood. Some of this could be accounted for by their even earlier onset cannabis use.¹⁷

Prevention

This is largely outside the clinical sphere with education and law enforcement leading in efforts to control abuse.

However, it should be remembered that historically there has been a link between overprescription of amphetamines and their misuse so that a culture of rational prescribing should be developed for their legitimate use.¹⁸

Stimulant therapy for ADHD should be initiated only by a psychiatrist with sufficient expertise to make the diagnosis. Where prescribing responsibility is transferred to primary care, this should be done under a shared-care agreement.¹⁹ Patients travelling to other countries with prescribed amphetamines should check the legal requirements of those countries before beginning their journey.

Where prescribed and used in a domestic or educational setting, provision should be made to ensure these drugs are not diverted for illicit use.