How it works
What does lorazepam do?
Lorazepam is a benzodiazepine medicine. Benzodiazepines help to calm people if they are anxious or finding it difficult to sleep. It can also be called an anxiolytic medicine. Anxiolytic is a word used to refer to any medicine that treats anxiety.
Lorazepam works by binding to a receptor in the brain for a chemical messenger called Gamma-aminobutyric acid (GABA) which has a calming effect. GABA usually binds to a receptor called GABA-A, found on nerve cells in the brain. When this happens, it inhibits the nerve cell from sending messages to other nerve cells. Lorazepam, like other benzodiazepines, also binds to the GABA-A receptor, but in a different position to GABA itself. When lorazepam binds to the GABA-A receptor, this makes it easier for GABA to do its job, increasing calming effects and helping to relieve anxiety.
Lorazepam is a controlled drug as it has the potential to be misused as a street drug. This means that:
- a prescription for lorazepam must be dispensed within 28 days (you can keep most other prescriptions for six months)
- if you must take it to school, it might have to be locked in a safe place
- you should allow plenty of time to get the prescription from the doctor and the pharmacy – controlled drug prescriptions may take more time to check
How long does lorazepam take to start working?
Lorazepam starts to work very quickly in your body.
You should get the calming effects from lorazepam in a few hours.
How long will I need to take lorazepam for?
It is not recommended to take lorazepam for more than four weeks at a time.
You and your doctor should talk about how long you need to take lorazepam before you start taking the medication.
People can become dependent on the effects of lorazepam if they take it for more than a month, and then when they stop, they get withdrawal symptoms.
If you take lorazepam for anxiety or sleeping you will probably take it for two to four weeks, to get you into a new routine, before stopping so that you do not get withdrawal symptoms.
Your doctor needs to know if...
You need to talk to your doctor or pharmacist before starting treatment with lorazepam if any of the following apply to you:
- you have severe breathing or chest problems
- you are allergic to benzodiazepines or any of the other ingredients in lorazepam tablets or liquid
- you have myasthenia gravis (very weak or tired muscles)
- you have sleep apnoea (breathing problems when you are asleep)
- you are breastfeeding, since the drug may pass into breast milk
- you are planning a pregnancy or are pregnant
- you have ever misused drugs or alcohol
- you have a personality disorder (you have a greater chance of becoming dependent on lorazepam)
- you have any kidney or liver problems
- you have depression, as lorazepam may increase any thoughts of harming yourself or taking your life
- you have had depression before (it could come back during treatment with lorazepam)
How can lorazepam be taken?
You can take lorazepam as a tablet or liquid, or it can be given by injection.
The tablets contain lactose and may not be suitable for you if you have problems eating some sugars or dairy (milk-based) products. The yellow 2.5mg tablets may also contain tartrazine (E102), a food additive that can cause allergic reactions. Check with your pharmacist if this is important.
The lorazepam oral solution is likely to contain alcohol but dose volumes will be small, so it should not significantly affect your blood alcohol levels.
The injection contains a very small amount of benzyl alcohol but this type of alcohol will not affect your blood alcohol levels.
You should only take lorazepam as agreed with your doctor
Make sure that you know your dose. If it is not written on the label, check with your pharmacist or doctor.
You may have to take lorazepam a few times each day.
If you are taking it to help you sleep, you should take it an hour before bedtime.
You can take it before or after food.
Swallow the tablet with a drink of water - if you chew it, it tastes 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 by more than three hours after you would normally take it, just start again when the next dose is due.
If you take it for sleeping, you must allow yourself between seven and 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 lorazepam?
If you forget to take your tablets for a few days, you may start getting your old symptoms back. This means that you should talk to your doctor about it.
Stopping the use of lorazepam
Do not stop taking lorazepam all at once. This could lead to serious symptoms, including:
- feeling unreal or detached from life, and an inability to feel emotions
- numbness or tingling of the arms or legs
- tinnitus (ringing sounds in the ears)
- oversensitivity to light, sound and touch
- uncontrolled or overactive movements
- twitching, shaking
- feeling sick, being sick, stomach upsets or stomach pain
- loss of appetite
- agitation, panic attacks
- fast heartbeat
- dizziness or feeling that you are about to fall
- memory loss
- feeling stiff and unable to move easily
- feeling very warm
- having seizures (fits) - this is more likely in people who have epilepsy
Depending how long you have been taking lorazepam, your doctor will help you to reduce the medication slowly over the course of several days or even weeks at the end of your treatment. Even when you do this, you may get some symptoms, including:
- muscle pain
- anxiety, tension, depression, restlessness, irritability or confusion
- your original sleeplessness may also return
If you suffer from any of these symptoms, go back to your doctor for advice.
The information on this page was reviewed by the College of Mental Health Pharmacy in March 2020.