How it works
What does diazepam do?
Diazepam improves the effect of a chemical in the brain called gamma-aminobutyric acid (GABA). GABA is a chemical whose transmission across nerves in the brain is known to produce a ‘calming effect’. When diazepam locks on to the GABA receptors in the brain, it changes shape - the GABA binds to it better and the calming effect of GABA is increased.
Diazepam is a 'controlled drug'. This means that a prescription for diazepam must be dispensed within 28 days (you can keep most other prescriptions for six months). This is because diazepam can be abused and might be sold as a street drug. If you must take it to school, it might have to be locked in a safe place.
How long does diazepam take to work?
Diazepam starts to work very quickly in your body, and you should get calming effects within two hours of taking it.
How long will I need to take diazepam?
People are not normally prescribed diazepam for more than four weeks as people can become dependent on it if they take it for longer. They may also get withdrawal symptoms when they stop taking it.
You and your doctor should talk about how long you might need to take diazepam.
If you take diazepam for anxiety or sleep problems you will probably take it for two to four weeks, to get you into a new routine.
Your doctor needs to know if...
You need to talk to your doctor or pharmacist before starting treatment with diazepam if any of the following apply to you:
- you’re allergic (hypersensitive) to diazepam or other benzodiazepine medicines, or to any of the other ingredients in your tablets
- you’re breathless or have difficulty breathing
- you have depression (with or without anxiety) or hyperactivity
- you have a phobia (a fear of an object or situation) or other mental illness
- you have myasthenia gravis
- you suffer from sleep apnoea (a condition where you stop breathing while asleep)
- you have severe liver disorder
- you have porphyria (an inherited condition causing skin blisters, gut pain and brain or nervous system disorders)
- you are planning a pregnancy or are pregnant
- you have a history of being dependent on drugs or alcohol
- you have problems with your heart and lungs or have severe kidney failure
- someone close to you has recently died
- you have low blood levels of a protein called albumin
- you have a personality disorder
You should only take diazepam as agreed with your doctor
You will get the best effect from diazepam if you take it regularly at the dose prescribed by your doctor. If this is not written on the label of your bottle or packet, please check with whoever prescribed the medication or ask your pharmacist for advice.
Some people are prescribed diazepam to be taken a few times a day. If this is the case, choose times you can always remember to take the medication, such as mealtimes or when you brush your teeth.
Some people may only have to take diazepam for one day, for instance before they have an operation.
You should not normally be prescribed diazepam for more than four weeks.
If you are taking diazepam to help you sleep, you should take it just before bedtime.
Diazepam can be taken before or after food. Swallow tablets whole with a drink of water – if chewed, they taste bitter.
What if I miss a dose?
If you remember later during the day, take it as soon as possible.
If you forget to take it and you are coming up to the time of your next dose (if it is four hours away or less), just take the next dose.
If you take it for sleeping, you must allow yourself seven to eight hours’ sleep after taking it. So, for example, do not take it if you have only got five hours left to sleep.
Do not take a double dose.
What will happen if I forget to take my diazepam?
If you forget to take your medicine for a few days, you may start to get some uncomfortable withdrawal effects, and you could get your old symptoms back.
Stopping the use of diazepam
Stopping diazepam quickly may cause withdrawal symptoms. If you have been taking a high dose, you may feel confused or behave strangely for a short time.
Do not stop taking diazepam all at once. This could lead to unpleasant withdrawal symptoms, including:
- depression, nervousness, or irritability
- quick or uneven heartbeat
- muscle spasms or shaking
- loss of appetite, feeling or being sick, stomach cramps or diarrhoea
- having seizures (fits)
Your doctor will help you to reduce diazepam slowly over a few days at the end of a short course of treatment. Otherwise the symptoms you are being treated for may return more intensely than before (rebound insomnia and anxiety).
The information on this page was reviewed by the College of Mental Health Pharmacy in March 2020.