Benzodiazepines have been available since the 1960s and have since been used to treat problems such as severe anxiety and insomnia. Before benzodiazepines, such conditions were treated with barbiturates, which were commonly linked to fatal overdoses. They are sometimes referred to as ‘benzos’ or BZD/BDZ. They should not be confused with the more recently introduced drugs BZP and ‘benzo fury’.

There are a wide variety of benzodiazepines, which differ in the balance of effects they have, and how long they last. The most well-known types include diazepam (Valium), temazepam, nitrazepam and others, usually with names ending in –pam or -lam. Flunitrazepam (Rohypnol) is a benzodiazepine but due to suggestions that it has been used as a ‘date rape drug’, it is now illegal in some European countries, outside of medical use.

Generally benzodiazepines are swallowed in tablet form, which is probably the least risky way of taking them. Very rarely some users may inject liquid benzodiazepine or snort crushed tablets.

Not all benzodiazepines used recreationally are diverted pharmaceutical products. Illicitly manufactured benzodiazepine tablets are frequently being encountered due to availability from the internet. These may resemble pharmaceutical preparations but are as unreliable as any other drugs on the unregulated market. The content of these preparations will vary and may not contain the drug expected.

Benzodiazepines are depressant drugs and have a ‘quietening’ effect on certain parts of the brain. This is why they are useful in treating conditions such as anxiety or panic attacks where certain parts of the brain may be overactive.

Because of their sedative and calming effects benzodiazepines are used short-term to treat sleep problems and anxiety disorders. They are also used to ease distress, panic and fear.

Benzodiazepines relax muscles and have anticonvulsant effects. They are useful in treating the withdrawal effects of alcohol, where they work to ease the agitation as well as preventing seizures, muscle spasms and shaking.

Benzodiazepines are also used longterm, although there are greater risks from long-term use.

All benzodiazepines reduce anxiety, and relax the mind and muscles, decrease alertness and concentration and reduce coordination. Depending on the dose and the individual, benzodiazepines can cause cosy sleepiness, or calm chattiness. At higher doses the sedating effects become stronger, and benzodiazepines can make a user slur, appear confused and lose consciousness unexpectedly. They can cause amnesia, or ‘blackouts’, where the user later has little or no memory of what has happened over a period of time.

Very occasionally benzodiazepines can have paradoxical effects. For instance, some people have become aggressive or violent when taking benzodiazepines. This is thought to be due to the disinhibiting effects of the drug.

If someone takes an overdose of a benzodiazepine, they can suffer unpleasant and potentially harmful effects. Overdoses can cause confusion, slurring, sleepiness, loss of coordination and collapse. If someone has taken enough to become unconscious, there is a risk of inhaling and choking on stomach contents which can potentially be fatal, and breathing can sometimes be depressed, especially in children. However, lasting harm or death from an overdose is very rare.

The danger of severe harm and death is very much greater if a benzodiazepine is taken with other sedative drugs such as alcohol, heroin or GHB. In these combinations, breathing can be depressed and stopped.

Emergency medical assistance should be sought when someone becomes unresponsive after taking drugs.

Benzodiazepines decrease control and impair judgment, making the risk of accidents much higher. This means activities like driving under the influence of benzodiazepines is potentially very dangerous.

The risks of depressed breathing caused by benzodiazepines are increased in people with conditions such as muscle weakness (e.g. myasthenia gravis), sleep apnoea, or lung disease/breathing disorders.

Taking benzodiazepines, particularly taking them regularly, may put someone at a greater risk of accidents. Doctors make a considered decision before prescribing them to people with impaired balance and coordination, who are at risk of falling or who may be severely injured if they do. It is also possible that long-term use of benzodiazepines could contribute to, or worsen, memory related problems or certain forms of dementia. This needs further scientific study as it is unclear if such effects would be reversed on stopping the drugs.

Taking benzodiazepines with depressant drugs increases the risk of depressing breathing. Additionally, the effects of benzodiazepines may be masked if taken with a stimulant, which can lead to an overdose if a lot of the drug is taken and then the stimulant wears off. Certain medications (e.g. some antidepressants) may also interact with benzodiazepines to increase sedative effects.

One-off or occasional use of benzodiazepines is very unlikely to result in the development of dependence. However, taking benzodiazepines regularly over a sustained period can cause very serious physical and psychological addiction. In fact, doctors are advised not to prescribe benzodiazepines for more than 4 weeks.

People who become dependent on benzodiazepines may become tolerant to the drug’s effects and experience withdrawal symptoms without it. Users may crave the drug and feel unable to cope without it. The longer the drugs are taken, the higher and more regular the dose and the stronger the benzodiazepines, the higher the risk of dependence.

A period of sustained dependence on any drug can be debilitating and prevent people from working and leading an active life. It may also cause mental and physical harm and benzodiazepine withdrawal can be very unpleasant.

Long term use of benzodiazepines is often accompanied with the use of other drugs, such as alcohol and opioids. This is because some users may feel that benzodiazepines enhance the effects of a drug, or lessen the effects of drug withdrawal/comedown, or both. Those who solely use benzodiazepines outside of medical use often do so after becoming dependent on them after being prescribed them for a medical condition.

Acute withdrawal effects for some benzodiazepines can be severe, although for many they will be milder. Acute withdrawal effects include anxiety, increased heart rate and blood pressure, shaking, insomnia and sensitivity to sound/light. Very severe withdrawal can cause symptoms that require intensive care, such as seizures. Someone who has been taking a benzodiazepine regularly for a sustained period should stop under the supervision and guidance of a doctor. Abruptly stopping use can be harmful so it is often better to taper use gradually before stopping entirely, and to do this safely professional advice is recommended.

Potential effects of long term benzodiazepine use include anxiety, depression and insomnia. These effects may last for months, depending on how dependent a person was on the drug, the drug used, the length of time used, untreated on-going psychiatric conditions, as well as other personal factors such as why the drug was initially prescribed or used illicitly.

There are possible harms of long term benzodiazepine use, although not everyone experiences problems with long term use. Specific harms that could be caused by long term benzodiazepine use include lack of energy, sleep problems, impaired memory and changes in personality (becoming more aggressive or depressed). Long term benzodiazepine use is also associated with anxiety related mental health problems such as panic disorder or social phobia. This may be because long term use causes the brain and body become reliant on the drug’s anxiety-relieving effects. It may therefore be particularly risky for people with depression/anxiety disorders to take benzodiazepines long term.

There is some evidence suggesting that long-term benzodiazepine may increase the risk of dementia. However, other experts think that the evidence of this is not yet convincing.

How much are you taking, how often?

The occasional medical or recreational use of benzodiazepines has a relatively low risk of harm. However, benzodiazepine dependence and withdrawal can develop after a few weeks of use and can cause considerable harm to quality of life and health. If you develop tolerance to any of the effects of a benzodiazepine, this should be taken as a warning sign that the drug may be harmfully affecting your body and brain.

Are you taking them with anything else? Mixing drugs is risky.

Drug effects are unpredictable, but mixing drugs makes the effects on your body and mind even harder to control. Deaths involving benzodiazepines generally involve other drugs too. It is particularly dangerous to combine a benzodiazepine with another drug that can depress breathing such as alcohol, heroin (or any opioid) or GHB. Additionally, if someone is taking antidepressants or even antihistamines, these may increase the effect of the benzodiazepines. Grapefruit juice can do the same with a few types of benzodiazepine. You should check whether this is possible if taking a benzodiazepine.

Support our work and help ensure that evidence-based research can influence policy and public opinion, not political or commercial agenda.

Drug Science is an independent, science-led drugs charity. We rely on donations to continue to promote evidence-based information about drugs without political or commercial interference.

We are grateful … But we need more. We can’t do it alone. Becoming a donor will help ensure we can continue our work. Join our Community and access opportunities to become more deeply engaged in our work.