Clomethiazole (Heminevrin)

How does it work?

Heminevrin capsules contain the active ingredient clomethiazole, which is a type of medicine called a non-benzodiazepine hypnotic. It acts in the brain to aid sleep.

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

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, reducing anxiety and relaxing muscles.

Clomethiazole can be used as a short-term treatment for insomnia and to treat agitation and restlessness in elderly people.

Clomethiazole can also be used to relieve the symptoms of alcohol withdrawal for alcoholics being treated in hospital.

What is it used for?

  • Agitation and restlessness in the elderly people.
  • Short-term treatment of severe insomnia in elderly people.
  • To help manage symptoms of alcohol withdrawal for people being treated in hospital for their addiction.

How do I take it?

  • Heminevrin capsules should be swallowed whole with or without food. The amount taken and how often varies from person to person, and according symptoms or condition that is being treated. It is important to follow the instructions given by your doctor and printed on the dispensing label.
  • For sleeping problems (insomnia) you should only take this medicine before going to bed at night. If you forget to take it at bedtime don’t take it at any other time, or you may end up feeling drowsy, dizzy and confused during the day.
  • If you are taking this medicine to help with alcohol withdrawal then your doctor will advise you to start on a high of dose of these capsules and reduce the amount you take gradually. Treatment with this medicine for alcohol withdrawal can only be used for a maximum of nine days.


  • This medicine causes drowsiness and impairs concentration and alertness. These effects may be made worse by drinking alcohol. If you are affected you should avoid potentially hazardous tasks such as driving or operating machinery. Do not drink alcohol when taking this medicine.
  • 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.
  • Depending on how long you have been taking this medicine for, your doctor may suggest that you stop taking it gradually to avoid withdrawal effects or a return in your sleeping problems. Follow the instructions given by your doctor.

Use with caution in

  • Elderly people.
  • Heart failure.
  • Decreased kidney function.
  • Severe liver damage or decreased liver function.
  • People with a history of drug abuse.
  • Personality disorders.
  • Syndrome involving short spells when breathing stops during sleep (sleep apnoea syndrome).
  • Disease affecting the airways or lungs such as chronic bronchitis and COPD.

Not to be used in

  • People with severe breathing problems or a sudden worsening of any underlying lung disease (acute pulmonary insufficiency).
  • Alcoholics who continue to drink.
  • Children.
  • Rare hereditary problems of fructose intolerance (Heminevrin capsules contain sorbitol).

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.

  • There is no information available about the safety of this medicine during pregnancy. It should not be used during pregnancy, particularly during the first and third trimesters, unless considered essential by your doctor. Seek medical advice from your doctor.
  • This medicine passes into breast milk. The effect on a nursing infant is not known. It should not be used by mothers who are breastfeeding unless considered essential by your doctor. Seek further medical advice from your doctor.

Label warnings

  • This medication causes drowsiness which may continue the next day. If affected do not drive or operate machinery. Avoid alcoholic drink.

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, it does not mean that all people using this medicine will experience that or any side effect.

  • Nasal congestion or irritation (this can occur with 15 to 20 minutes of taking the capsules).
  • Eye irritation.
  • Headache.
  • Confusion.
  • Disturbances of the gut such as diarrhoea, constipation, nausea, vomiting or abdominal pain.
  • Unexpected over excitement.
  • Skin reactions such as rash, itchy nettle-type rash.
  • Elevation in levels of liver enzymes.
  • Severe allergic reaction.

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 taking this one, to ensure that the combination is safe.

The sedative effect of this medicine will be increased if this medicine is taken with any of the following, which can also cause drowsiness:

  • alcohol
  • antipsychotics, eg chlorpromazine, haloperidol
  • barbiturates, eg phenobarbital, amobarbital
  • lofexidine (used to treat drug dependence)
  • MAOI antidepressants, eg phenelzine
  • moxonidine (used to treat high blood pressure)
  • muscle relaxants, eg baclofen, tizanidine
  • nabilone (an antisickness medicine)
  • other sleeping tablets, eg diazepam, zopiclone
  • sedating antihistamines, eg chlorphenamine, hydroxyzine, promethazine
  • strong opioid painkillers, eg morphine, codeine
  • tricyclic and related antidepressants eg amitriptyline, mirtazapine.

Cimetidine may increase the amount of clomethiazole in your blood and this could increase its sedative effect, as well as increase the risk of its side effects.

Carbamazepine may decrease the amount of clomethiazole in the blood and make it less effective.

Other medicines containing the same active ingredient

There are currently no other medicines available in the UK that contain clomethiazole as the active ingredient.