Benzodiazepines and Z Drugs

Benzodiazepines and Z drugs are sometimes prescribed for short periods to ease symptoms of anxiety and sleeping difficulty, and also occasionally for other reasons. A benzodiazepine or a Z drug will often work well in the short term but is not normally advised for more than 2-4 weeks. If you take it for longer, the medicine may lose its effect (you may become tolerant to the effect) and you may also become addicted to it (dependent on it). Sometimes the symptoms you are left with after long-term use of these medicines are worse than the symptoms for which they were originally given.


Benzodiazepines are a group of medicines that are sometimes used to treat anxiety, sleeping problems and other disorders. Examples include diazepam, lorazepam, chlordiazepoxide, oxazepam, temazepam, nitrazepam, loprazolam, lormetazepam, clobazam and clonazepam.

Benzodiazepines work by affecting the way certain brain chemicals (neurotransmitters) transmit messages to certain brain cells. In effect, they decrease the excitability of many brain cells. This has a calming effect on various functions of the brain.

Z drugs

Medicines called zaleplon (no longer available in the UK), zolpidem and zopiclone are commonly called the Z drugs. Strictly speaking, Z drugs are not benzodiazepines but are another class of medicine. However, they act in a similar way to benzodiazepines. (They have a similar effect on the brain cells as benzodiazepines.) Z drugs have similar long-term usage problems as benzodiazepines.

Benzodiazepines for anxiety

Symptoms of anxiety include: agitation, tension, irritability, the sensation of having a 'thumping heart' (palpitations), shakiness, sweating, excess worry, sleeping badly, poor concentration, fast breathing and sometimes a knotted feeling in the stomach and other muscles. There are various causes of anxiety. Sometimes it is a sudden life crisis such as a bereavement or redundancy. Some people have an anxious personality and feel anxious fairly often. Sometimes anxiety can be one of the symptoms of depression. Although most people will feel anxious at some time, sometimes the symptoms become prolonged and distressing. See separate leaflet called Anxiety.

Treatments for anxiety include: relaxation exercises, anxiety management courses and cognitive therapy and behavioural therapy. Simply talking things over with a friend, counsellor, or with members of a self-help group may also help. However, if symptoms become very severe, you may occasionally be advised to take a benzodiazepine medicine for a short time.

Benzodiazepines and Z drugs as sleeping tablets

A short course of a benzodiazepine or a Z drug may be prescribed if a medicine is felt necessary to help with sleeping difficulty (insomnia). See separate leaflet called Sleeping Tablets for more details. However, there are other ways of helping to get a good night's sleep. See separate leaflet called Insomnia (Poor Sleep).

Other uses of benzodiazepines

A dose of a benzodiazepine is often given as a 'pre-med' to reduce anxiety before an operation. A large dose is commonly given as a sedative during medical procedures that may cause anxiety or discomfort. The medicine not only reduces anxiety but also has an amnesic effect. This means that you do not remember much about the procedure afterwards. Some benzodiazepines are occasionally used to treat muscle spasm and certain types of epilepsy as they can prevent fits (seizures). Others are used to help people who are dependent on alcohol and trying to stop.

If you are not used to taking benzodiazepines or Z drugs, the first doses are usually good at easing symptoms of anxiety or promoting sleep. A benzodiazepine does nothing to remove any underlying cause of anxiety such as a life crisis. However, if your symptoms are eased, you may be able to cope better with any problems.

Benzodiazepines and Z drugs work best in situations where anxiety or sleeping difficulty is expected to last only a short while. They are not so useful if you have an ongoing anxious personality or long-term sleeping difficulty. However, a short course may help you over a particularly bad spell.

You can usually stop a benzodiazepine or a Z drug without any problems if you take it for just a short period of time (no more than 2-4 weeks).

When benzodiazepines were first used they were thought to be safe. The problems with their long-term use were not known. In 1981, benzodiazepines were the most commonly prescribed medicines in western countries. It was because benzodiazepines worked so well to ease symptoms of anxiety and poor sleep that many people came back for more. Some people started to take them regularly.

However, it is now known that if you take a benzodiazepine or a Z drug for more than 2-4 weeks, you may develop problems (see below). Therefore, most doctors will now only prescribe benzodiazepines and Z drugs for a short period.


If you take a benzodiazepine or Z drug regularly, the helpful effect on easing anxiety or in helping sleep usually lasts for a few weeks. However, after a few weeks, the body and brain often become used to the benzodiazepine or Z drug. The medicine then gradually loses its effect. The initial dose then has little effect. You then need a higher dose for it to work. In time, the higher dose does not work and you need an even higher dose and so on. This effect is called tolerance.


There is a good chance that you will become addicted to (dependent on) a benzodiazepine or a Z drug if you take it for more than four weeks. This means that withdrawal symptoms occur if the tablets are stopped suddenly. In effect, you need the medicine to feel normal. Possible withdrawal symptoms include:

  • Psychological symptoms - such as anxiety, panic attacks, odd sensations, feeling as if you are outside your body, feelings of unreality, or just feeling awful. Rarely, a serious mental breakdown can occur.
  • Physical symptoms - such as sweating, being unable to sleep, headache, tremor, feeling sick (nausea), the sensation of having a 'thumping heart' (palpitations), muscle spasms and being oversensitive to light, sound and touch. Rarely, convulsions occur.
  • In some cases the withdrawal symptoms seem like the original anxiety symptoms.

The duration of withdrawal symptoms varies but often lasts up to six weeks and sometimes longer. Withdrawal symptoms may not start for two days after stopping the tablet and tend to be worst in the first week or so. Some people have minor residual withdrawal symptoms for several months.

Therefore, you may end up taking the medicine to prevent withdrawal symptoms but, because of tolerance, the medicine is no longer helping the original anxiety or sleeping problem. But note: you are unlikely to become dependent on a benzodiazepine or a Z drug if you take it for a short period only.

Even if you take a benzodiazepine or Z drug for a short time, you may feel drowsy during the daytime. Some people, especially older people, are at greater risk of having a fall and injury because of the drowsiness. If you drive, you may be more likely to be involved in a car crash. Some people have described themselves as being in a zombie state when they were taking a benzodiazepine on a long-term basis.

For a full list of possible side-effects whilst taking any tablet, read the leaflet that comes with the packet of tablets.

If you think you have had a side-effect to one of your medicines you can report this on the Yellow Card Scheme. You can do this online at the following web address:

The Yellow Card Scheme is used to make pharmacists, doctors and nurses aware of any new side-effects that medicines or any other healthcare products may have caused. If you wish to report a side-effect, you will need to provide basic information about:

  • The side-effect.
  • The name of the medicine which you think caused it.
  • The person who had the side-effect.
  • Your contact details as the reporter of the side-effect.

It is helpful if you have your medication - and/or the leaflet that came with it - with you while you fill out the report.

Benzodiazepines and Z drugs can sometimes be misused by people taking drugs for recreational purposes. The Misuse of Drugs Act was a law passed in 1971 in the UK to try to prevent the use of harmful drugs. It divides drugs into three categories - A, B or C, depending on how dangerous they are thought to be. Each of the categories then has different penalties for those convicted of use or supply. Benzodiazepines and Z drugs are classed as Class C drugs. This means it is illegal to be in possession of them if they have not been prescribed for you by a doctor. People found in possession illegally, or attempting to supply them to others, could face a fine or a prison sentence. There are also special rules for doctors prescribing them.


People on normal doses of benzodiazepines and Z drugs prescribed by their doctor do not need to inform the Driver and Vehicle Licensing Agency (DVLA). However, if you are taking higher doses than recommended, or taking them without prescription, your driving licence would be taken away.

If you have been taking a benzodiazepine or a Z drug for over four weeks and want to come off it, it is best to discuss the problem with a doctor. Some people can stop taking benzodiazepines or Z drugs with little difficulty. However, many people develop withdrawal symptoms if they suddenly stop taking a benzodiazepine or a Z drug. To keep withdrawal effects to a minimum, it is often best to reduce the dose of the medicine gradually over a number of weeks or months before finally stopping it. Your doctor will advise on dosages, timescale, etc.

See separate leaflet called Stopping Benzodiazepines and Z Drugs.

Now read about Benzodiazepine Dependence

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Dr Laurence Knott
Peer Reviewer:
Dr John Cox
Document ID:
4207 (v43)
Last Checked:
29 July 2017
Next Review:
28 July 2020

Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. Patient Platform Limited has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. For details see our conditions.