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Sleeping pills and minor tranquillisers

Explains what sleeping pills and minor tranquillisers are used for, how the medication works, possible side effects and information about withdrawal.

Non-benzodiazepine sleeping pills

This page has information about non-benzodiazepine medications that you may be prescribed to help you sleep. See our page on benzodiazepines for information about benzodiazepine sleep medications.

This page includes a table to help you compare non-benzodiazepine sleeping pills by different factors.

There is also information explaining different types of non-benzodiazepine sleeping pill:

Although we use the term ‘sleeping pills’ to describe these drugs, some of them may also be available as a liquid, either to swallow or for injection.

Comparing non-benzodiazepine sleeping pills

This table lists all of the non-benzodiazepine sleeping pills currently licensed for use in the UK.

Some of these drugs have more than one name. You might know a drug by its generic name or its trade name. See our page on drug names for more information.

Drag or scroll this table to view full contents

Generic name

Trade names (UK)

Forms available

Half-life

Dietary considerations

chloral hydrate (or cloral betaine)

Welldorm

  • liquid (chroral hydrate)
  • tablet (cloral betaine)

more than 6 days

none

clomethiazole (sometimes spelled chlormethiazole)

Heminevrin

  • capsules
  • liquid

3.6 to 5 hours

  • capsules contain gelatin

diphenhydramine

Sleep aid tablets (many brands are available)

  • tablets

2.4 to 9.3 hours

  • contains lactose

melatonin

Circadin
Slenyto
Syncrodin

  • tablets
  • prolonged release tablet
  • liquid

0.5 to 4 hours

  • contains lactose

promethazine

Phenergan
Sominex
Some brands of 'night cold and flu' medication

  • tablets
  • liquid
  • injection (only to be administered by healthcare professionals)

5 to 14 hours

  • tablets contain lactose

zolpidem

Stilnoct

  • tablets

around 2.4 hours

  • contains lactose

zopiclone

Zimovane

  • tablets

around 5 hours

  • contains lactose

The Z drugs

The Z drugs are non-benzodiazepine sleeping pills, used to treat severe insomnia (difficulty getting to sleep or staying asleep). They are known as the Z drugs because their generic names begin with the letter ‘z'.

The Z drugs currently licensed for prescription in the UK are zolpidem and zopiclone. The medication zaleplon used to be included in this group, but it is no longer licensed for use in the UK.

These drugs are not benzodiazepines, but they act in a very similar way. This includes causing similar problems with dependence and withdrawal.

They are short-acting drugs, which means their effects last for a short period. And they are less likely to have a ‘hangover’ effect than some other types of sleep medication.

When might I be prescribed a Z drug?

Your doctor should only prescribe you a Z drug if you are experiencing severe insomnia. And they should only do this after you have tried other, non-medication treatments.

If your doctor prescribes you a Z drug, they should:

  • give you the lowest dose that has an effect
  • prescribe them for the shortest time possible
  • prescribe them strictly according to the licence for that specific drug.

If you are an older person, your doctor may offer you a Z drug ahead of other sleep medication. This is because any negative effects from these drugs are likely to last for less time than with other sleep medication. But you should still take them for the shortest time possible.

Who should avoid taking Z drugs?

Your doctor will not normally prescribe you Z drugs if you have:

  • severe lung disease or breathing problems
  • sleep apnoea (breathing problems during sleep)
  • severe liver or kidney disease
  • severe and uncontrolled myasthenia gravis (a neuromuscular condition).

Your doctor may be cautious about offering you Z drugs if you have:

Your doctor should prescribe a reduced dose of these drugs if you have:

  • liver or kidney problems
  • porphyria (a rare, inherited illness).

There may be risks with taking these drugs if you are pregnant or breastfeeding. But there is not enough research to know exactly how common these problems may be.

If you are pregnant, breastfeeding or planning to become pregnant, you can speak to your doctor about the risks and benefits of taking a Z drug. They can help you make the best decision for your situation.

How should I take Z drugs?

If you are taking Z drugs, you should:

  • try not to take them with food or straight after eating, as this may make them work more slowly
  • avoid taking them with alcohol
  • not take a second dose in one night
  • take them when you are ready for sleep, and not before. After taking them, you may feel unsteady or clumsy if you need to get up in the night, such as to go to the toilet.

You shouldn’t normally take sleeping pills for more than three weeks. Ideally, you would take them for no more than one week.

How should I come off Z drugs?

When you stop taking Z drugs, you should withdraw from them gradually to avoid negative withdrawal effects. And if you find that one Z drug doesn’t work for you, your doctor should not prescribe you another Z drug to try instead.

Z drugs and dangerous activity during sleep

All Z drugs can sometimes cause a type of sleep-walking, when you may get up and do things while you are not really awake. These include:

  • dangerous activities like driving
  • eating, including inappropriate food (such as raw food that should be cooked)
  • having sex
  • being violent to your bed partner.

When you wake up you may not remember anything about what you have done.

If you are taking a Z drug and you carry out dangerous activities while you sleep, you should tell your doctor about this immediately.

"In the past I have suffered manic and psychotic episodes. Being able to sleep was important in helping me recover, so the 'Z' drugs they gave me in hospital really helped."

Antihistamines

Antihistamines are a type of medication mainly used for treating symptoms of allergies, such as hay fever. But some of them also have drowsiness as a side effect. These drugs can also be used to help with short-term insomnia.

You can buy the following drugs without a prescription from a pharmacist, to help with insomnia:

These are long-acting medications, which means their effects last for a longer time. This also means they are more likely to leave a ‘hangover’ effect the day after you take them.

They may also be slow to act, which means they may not make you feel sleepy straight away. And they may lose their effectiveness if you take them for a few days.

If you take antihistamines but they are no longer helping you sleep, you can speak to your pharmacist for advice.

Who should avoid taking antihistamines?

Your doctor or pharmacist may advise you to be cautious about taking antihistamines if you have:

  • an enlarged prostate gland
  • problems urinating (urinary retention)
  • glaucoma (raised pressure in the eye)
  • liver disease
  • epilepsy
  • porphyria (a rare, inherited illness).

Your doctor or pharmacist may advise you to avoid taking antihistamines if you are pregnant or breastfeeding. But there may be certain cases when your doctor will recommend or prescribe this medication.

If you are pregnant, breastfeeding or planning to get pregnant, you can speak to your doctor or pharmacist if you have questions about taking antihistamines. They can give you the best advice for your situation.

Side effects of antihistamines

Common side effects of antihistamines include:

  • disorientation (feeling confused about where you are)
  • dizziness
  • headaches
  • nightmares
  • restlessness
  • tiredness.

Occasional side effects of antihistamines include:

  • blurred vision
  • confusion
  • dry mouth
  • excitement
  • urinary retention.

These occasional side effects are more common in older people. Children may also be more likely to experience excitement as a side effect.

Rare side effects of antihistamines include:

  • blood cell disorders
  • disturbances of heart rhythm
  • loss of appetite
  • low blood pressure
  • muscle spasms
  • sensitivity to sunlight
  • shaking
  • stomach discomfort
  • tic-like movements.

You can speak to your doctor or pharmacist if you are unsure whether antihistamines are suitable for you. This includes letting them know if you are taking any other medication, including herbal remedies.

Melatonin

Melatonin is a natural hormone produced by your pineal gland. This is a gland in your brain which regulates your body’s response to the 24-hour cycle of day and night.

Melatonin is also available as a medication to help with insomnia. It is usually offered as a short-term medication for people aged 55 and over.

It is not generally recommended for anyone under the age of 18. But it may be offered to them in certain circumstances. Your doctor may also avoid prescribing you melatonin if you are pregnant or breastfeeding. You can speak to your doctor or pharmacist if you are concerned about this.

Chloral hydrate and clomethiazole

Chloral hydrate and clomethiazole are older drugs with many side effects, including possible dependence. Chloral hydrate is a liquid drug, but it may also be available in tablet form called cloral betaine. And clomethiazole may also be spelled chlomethiazole.

These drugs are not usually offered nowadays as medication for insomnia. But they may be used in some rare circumstances. Your doctor may avoid prescribing you these medications if you are pregnant or breastfeeding. They may also be cautious about prescribing them if you have a history of drug or alcohol abuse, or a diagnosis of a personality disorder.

If you are chloral hydrate, you should avoid it coming into contact with your skin as it may cause skin damage.

Barbiturates

Barbiturates were used as sedatives before benzodiazepines became available. They are rarely prescribed nowadays.

You should only be offered them to treat severe insomnia if:

  • you are already taking barbiturates
  • other treatments have not helped your insomnia.

Barbiturates should not be offered to older people.

This information was published in April 2021. We will revise it in 2024. 

References are available on request. If you would like to reproduce any of this information, see our page on permissions and licensing.

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