Lorazepam (Ativan)

How does it work?

Ativan injection contains the active ingredient lorazepam, which is a type of medicine called a benzodiazepine. Benzodiazepines are used for their sedative, anxiety-relieving and muscle-relaxant effects.

Lorazepam works by acting on receptors in the brain called GABA receptors. This causes the release of a neurotransmitter called GABA in the brain.

Neurotransmitters are chemicals that are stored in nerve cells in the brain and nervous system. They are involved in transmitting messages between the nerve cells. GABA is a neurotransmitter that acts as a natural 'nerve-calming' agent. It helps keep the nerve activity in the brain in balance, and is involved in inducing sleepiness and reducing anxiety.

As lorazepam increases the activity of GABA in the brain, it increases its calming effect and results in sleepiness, a decrease in anxiety and relaxation of the muscles.

Lorazepam is used to calm severe anxiety and related conditions, such as acute mania, excitement or agitation. Benzodiazepines such as lorazepam are effective at quickly reducing the symptoms of anxiety and agitation that occur in a manic or hypomanic episode of the psychiatric illness, bipolar affective disorder. Benzodiazepines help calm the individual while the main medicines used to treat this condition (mood stabilisers) begin to take effect.

Lorazepam is also given for its sedating and anxiety-relieving effects as a pre-med before surgery or medical investigations that may be uncomfortable or prolonged, for example bronchoscopy or endoscopy.

Lorazepam injection is also used to control repeated epileptic fits or seizures when a patient does not recover conciousness between fits (status epilepticus). It works in this instance because the increased activity of GABA in the brain helps to calm excessive electrical nerve activity in the brain that is responsible for causing seizures.

Lorazepam is given by injection when a rapid effect is needed.

What is it used for?

  • Short-term treatment of severe anxiety, agitation or excitement that is disabling or subjecting the individual to unacceptable distress.
  • Short-term treatment of acute mania.
  • Relieving anxiety and causing sedation before surgery or medical procedures (pre-med).
  • Controlling repeated fitting with no recovery of conciousness between seizures (status epilepticus).


  • This medicine causes drowsiness, muscle weakness and impairs concentration and alertness. These effects may continue into the following day and are made worse by drinking alcohol. If you are affected you should avoid potentially hazardous tasks such as driving or operating machinery. You should not drink alcohol for 24 to 48 hours after having an Ativan injection.
  • This medicine is generally only suitable for short-term use. If it is used for long periods or in high doses, tolerance to and dependence upon the medicine may develop, and withdrawal symptoms may occur if treatment is stopped suddenly.
  • Treatment with this medicine should usually be stopped gradually, following the instructions given by your doctor, in order to avoid withdrawal symptoms such as rebound insomnia or anxiety, confusion, sweating, tremor, loss of appetite, irritability or convulsions.

Use with caution in

  • Children.
  • Elderly people.
  • Weak or debilitated people.
  • Decreased kidney function.
  • Decreased liver function.
  • Disease affecting the airways or lungs (respiratory disease).
  • Depression.
  • History of alcoholism or drug abuse.
  • Personality disorders.
  • Closed angle glaucoma.

Not to be used in

  • Allergy to benzodiazepines.
  • Severely decreased liver function.
  • A sudden worsening of any underlying lung disease (acute pulmonary insufficiency).
  • Slow, shallow breathing (respiratory depression).
  • Syndrome involving short spells when breathing stops during sleep (sleep apnoea syndrome).
  • Abnormal muscle weakness (myasthenia gravis).
  • Breastfeeding.
  • Ativan injection must not be given to children under three years of age.
  • Ativan injection is not recommended as a pre-med or to treat acute anxiety states in children under 12 years of age.

This medicine should not be used if you are allergic to any of its ingredients. Please inform your doctor or pharmacist if you have previously experienced such an allergy.

If you feel you have experienced an allergic reaction, stop using this medicine and inform your doctor or pharmacist immediately.

Pregnancy and breastfeeding

Certain medicines should not be used during pregnancy or breastfeeding. However, other medicines may be safely used in pregnancy or breastfeeding providing the benefits to the mother outweigh the risks to the unborn baby. Always inform your doctor if you are pregnant or planning a pregnancy, before using any medicine.

  • This medicine may be harmful to a developing baby and it should be avoided during pregnancy unless considered essential by your doctor. This is particularly important during the first and third trimesters of pregnancy and before or during labour. Regular use during pregnancy should especially be avoided, as the baby could become dependent on the medicine and then suffer withdrawal symptoms after the birth. If this medicine is used in late pregnancy or during labour it may cause floppiness, low body temperature and breathing or feeding difficulties in the baby after birth. Ask your doctor for further information.
  • Significant amounts of this medicine may pass into breast milk. It should not be used by breastfeeding mothers as it may be harmful to the nursing infant. Seek medical advice from your doctor.

Side effects

Medicines and their possible side effects can affect individual people in different ways. The following are some of the side effects that are known to be associated with this medicine. Just because a side effect is stated here does not mean that all people using this medicine will experience that or any side effect.

  • Drowsiness.
  • Drowsiness and lightheadedness the next day.
  • Confusion.
  • Loss of memory (amnesia).
  • Headache.
  • Dizziness.
  • Blurred or double vision.
  • Nausea and vomiting.
  • Restlessness.
  • Depression.
  • Crying.
  • False perceptions of things that are not really there (hallucinations).
  • Blood disorders.
  • Skin rashes.
  • Low blood pressure (hypotension).
  • Shaky movements and unsteady walk (ataxia).
  • Muscle weakness.
  • Disturbances of the gut such as diarrhoea, constipation or abdominal pain.
  • Unexpected increase in aggression (paradoxical aggression).
  • Pain and redness at the injection site.

The side effects listed above may not include all of the side effects reported by the medicine's manufacturer.

For more information about any other possible risks associated with this medicine, please read the information provided with the medicine or consult your doctor or pharmacist.

How can this medicine affect other medicines?

It is important to tell your doctor or pharmacist what medicines you are already taking, including those bought without a prescription and herbal medicines, before you start treatment with this medicine. Similarly, check with your doctor or pharmacist before taking any new medicines while being treated with this one, to make sure that the combination is safe.

There may be an increased risk of drowsiness and sedation if lorazepam is used with any of the following (which can also cause drowsiness):

  • alcohol
  • antipsychotics, eg chlorpromazine, clozapine
  • barbiturates, eg phenobarbital
  • other benzodiazepines, eg temazepam
  • MAOI antidepressants, eg phenelzine
  • sedating antihistamines, egchlorphenamine
  • sleeping tablets, eg zopiclone
  • strong opioid painkillers, eg morphine, codeine, dihydrocodeine
  • tricyclic antidepressants, egamitriptyline.

There may be increased sedation, excessive salivation and irregular muscular movement, such as shaking and unsteady walking if lorazepam is taken with clozapine.

Probenecid and sodium valproate may prevent the breakdown of lorazepam in the body. As this could increase the blood level of lorazepam and its sedative effects, as well as the risk of its side effects, your doctor may need to prescribe you a lower than normal dose of lorazepam if you are taking probenecid.

Caffeine and theophylline may reduce the sedative and anxiety-reducing effects of lorazepam.

Other medicines containing the same active ingredient

Lorazepam tablets