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What are benzodiazepines?

Benzodiazepines are classified as depressants. They slow down the activity of the central nervous system and the messages travelling between the brain and the body. Other depressants include alcohol, cannabis and heroin.

Benzodiazepines, also known as ‘benzos’, are a type of sedative. They have anxiolytic (anxiety-reducing), sedative and muscle relaxant effects (Quick Guide to Drugs and Alcohol, 2017). They are prescribed for a range of problems, including anxiety and insomnia.

Benzodiazepines are classified on the basis of their duration of action: long-acting, intermediate-acting and short-acting. Short-acting benzodiazepines have stronger withdrawal or ‘come down’ effects and can be more addictive than long-acting benzodiazepines (ADF, 2020).

Benzodiazepines are commonly prescribed medications. They are usually prescribed in tablet or capsule form for oral use; however, they are occasionally used in other ways, including by injection.

What are the effects?

Benzodiazepines can cause feelings of relaxation and mild contentment, or even sedation and total blackout. Once swallowed, they usually take about half an hour to take effect. The duration of the effects varies.

The effects of benzodiazepines may include:

  • Muscle relaxation
  • Slurred speech
  • Slow pulse rate
  • Blurred vision
  • A feeling of calmness
  • Confusion
  • Loss of balance and coordination
  • Drowsiness
  • A ‘hangover’ effect the following day
  • Shallow breathing
  • Blackouts
  • Dizziness

What are the risks?

If used as prescribed and recommended, benzodiazepines are safe and effective medications. However, there are risks, particularly if they are used at high doses, they’re not used properly, or are used regularly (e.g. daily) for more than a few weeks.

The risks of benzodiazepines include:

  • Sedation, including impaired driving the day following use
  • Dependence
  • Aggression or violence, particularly if the dose is high, the person is quite impulsive, has a history of aggression, or is also under the influence of alcohol
  • Skin and vein problems (if injected)
  • Withdrawals (if dependence has formed), which can lead to seizures and death if not managed correctly
  • Blackouts
  • Overdose, especially if the person also drinks alcohol, uses other depressant drugs (e.g. heroin) or takes opioid painkillers (e.g. oxycodone or morphine)

Mixing benzodiazepines with other drugs

The effects of taking benzodiazepines with other drugs can be unpredictable and dangerous.

Benzodiazepines and alcohol or opioids (such as heroin) could cause breathing difficulties, an increased risk of overdose and death.

Benzodiazepines and some pharmaceutical drugs (such as opioid pain-relievers, antidepressants, anticonvulsants, antipsychotics, some antihistamines and over the counter medications) could lead to breathing difficulties, increased risk of overdose and death.

The use of benzodiazepines to help with the come down effects of stimulant drugs (such as amphetamines or ecstasy) may result in a cycle of dependence on both types of drug (ADF, 2020)

Toxicity and overdose

Overdosing on a benzodiazepine alone rarely results in death, although high doses of benzodiazepines can lead to unconsciousness or even coma. A person who has taken an excessive dose can die by passing out and suffocating on vomit or mucus.

Benzodiazepines are commonly implicated in overdoses with multiple medications or substances. If benzodiazepines are taken with other depressants, such as alcohol, heroin or prescribed pain medication, the possibility of fatal overdose is increased (Quick Guide to Drugs and Alcohol, 2017).

Dependence and withdrawal

Benzodiazepines are addictive and only recommended for short-term use. Tolerance can develop quickly, which means that dosage must be increased to get the same effect, increasing the chances of dependence. It is possible to become dependent and suffer withdrawal symptoms after only two weeks of regular use. Dependence can result in cravings and/or physical withdrawal symptoms when benzodiazepines are stopped (Quick Guide to Drugs and Alcohol, 2017).

Withdrawal symptoms vary from person to person and are different depending on the type of benzodiazepine being taken. Symptoms may include:

  • Headaches
  • Aching or twitching muscles
  • Dizziness and tremors
  • Nausea, vomiting, stomach pains
  • Bizarre dreams, difficulty sleeping, fatigue
  • Poor concentration
  • Anxiety and irritability
  • Altered perception, heightening of senses
  • Delusions, hallucinations and paranoia
  • Seizures

Symptoms can be decreased by gradually reducing the dose rather than stopping suddenly (Quick Guide to Drugs and Alcohol, 2017).

Mental health

In 2019, compared with people who had not been diagnosed or treated for a mental health condition in the previous 12 months, people with a mental health condition were 2.1 times as likely to use pharmaceuticals for non-medical purposes (7.6 percent compared with 3.6 percent) (AIHW, 2020).


Treatment for benzodiazepine dependence involves a gradual withdrawal of the drug under medical supervision. Doses are often reduced gradually over weeks or months.

Psychological treatments aimed at keeping the person motivated and improving their coping skills are recommended to maintain recovery. Where anxiety or insomnia were part of the original reason for using benzodiazepines, treatments like cognitive behavioural therapy (CBT) can be useful to develop other strategies to deal with these symptoms without using benzodiazepines. Research shows that in the long-term, CBT can be more effective than benzodiazepines for insomnia and anxiety. Good social support can also be very helpful (Quick Guide to Drugs and Alcohol, 2017).

Emergency info

If you, or someone around you, is experiencing undesired or distressing psychological or physical symptoms from the intake of alcohol or other drugs please seek immediate medical attention.

If you need urgent help from ambulance services call Triple Zero (000). If a person has been mixing drugs with alcohol or other drugs, tell the paramedic exactly what has been taken.


For free and confidential advice about alcohol and other drugs, call the National Alcohol and Other Drug hotline on 1800 250 015.

The hotline will automatically direct you to the Alcohol and Drug Information Service in your state or territory.

More resources

The Illicit Drug Reporting System is an Australian monitoring system that identifies emerging trends of local and national interest in illicit drug markets.

The Ecstasy and Related Drugs Reporting System is an Australian monitoring system for ecstasy and related drugs that identifies emerging trends of local and national interest.

The Clinician’s Guide to Illicit Drugs and Health examines the health effects of each of the major illicit drugs.

The Australian Institute of Health and Welfare collects information on alcohol and tobacco consumption, and illicit drug use among the general population in Australia.

The Australian Bureau of Statistics is Australia’s national statistical agency, providing official statistics on a range of economic, social, population and environmental matters of importance to Australia.


A Quick Guide to Drugs and Alcohol (3rd ed.) (2017). Sydney, Australia: Drug Info.

Alcohol and Drug Foundation (2019). Benzodiazepines. Retrieved from

Australian Institute of Health and Welfare (2020). National Drug Strategy Household Survey 2019. Retrieved from


Date Commenced
13 Jan 2021
Resource Type
Fact Sheets