chloral hydrate at a glance
Medicine class
Sedative and hypnotic
Licensed role
Severe insomnia affecting daily life after other approaches have failed
Form
Prescription-only oral solution, measured with an oral syringe or suitable medicine measure
Driving
May cause drowsiness and impair driving or machinery use
What is chloral hydrate used for?
Licensed use is restricted. Other uses require specialist assessment and may be outside the licence.
Adults: severe insomnia interfering with normal daily life when behavioural and pharmacological therapies have failed, alongside non-drug measures.
Children and adolescents aged 2 years and over: severe insomnia associated with a suspected or confirmed neurodevelopmental disorder, after other therapies have failed and under medical-specialist supervision.
Paediatric procedural or critical-care sedation is outside the licensed insomnia indication and requires particular caution in infants and neonates.
How does chloral hydrate work?
Chloral hydrate is rapidly converted to trichloroethanol, which depresses central nervous system activity and produces sedation and sleepiness.
chloral hydrate preparations and strengths
Oral solution
Route: Oral
Strengths: 143 mg/5 mL, 500 mg/5 mL
How to take chloral hydrate
Take the oral solution exactly as shown on the prescription label. The selected products do not require dilution, although they may be taken with water or milk.
Measure it with an oral syringe or appropriate medicine measure, not a kitchen teaspoon.
Check the bottle concentration because different-strength solutions are available.
For the 500 mg/5 ml product, use the supplied bottle adaptor, remove syringe air bubbles, and wash and dry the syringe after use.
Do not automatically repeat it after vomiting; ask a healthcare professional first.
chloral hydrate side effects
Common or expected effects
- Drowsiness or sedation
- Stomach irritation, nausea or vomiting
- Headache
- Confusion or unusual excitement
- Poor coordination or unsteadiness
- Abdominal bloating or wind
- Allergic skin reactions
Get urgent medical advice
- Slow or difficult breathing
- Marked sedation, reduced consciousness or coma
- Fast or irregular heartbeat, fainting or collapse
- Severe allergic reaction
- Severe or persistent abdominal pain or vomiting
- Delirium or hallucinations, particularly after abrupt withdrawal following prolonged use
chloral hydrate in pregnancy
The selected product information advises against use during pregnancy. Human evidence is limited and chloral hydrate crosses the placenta. Discuss pregnancy or plans for pregnancy with the prescriber.
chloral hydrate while breastfeeding
The selected product information advises against use while breastfeeding. Small amounts can enter breast milk and may sedate the infant, so specialist or prescriber advice is needed.
chloral hydrate interactions
Chloral hydrate has additive sedative effects and important cardiac, anticoagulant and laboratory interactions.
Alcohol
Can substantially increase sedation and should be avoided.
Other central nervous system depressants
Opioids, sedatives, hypnotics, antipsychotics, antidepressants, antiepileptics, anaesthetics, sedating antihistamines and centrally acting muscle relaxants can increase central and respiratory depression.
Common questions about chloral hydrate
Answers are fully visible for fast scanning and source review.
Why is chloral hydrate not usually a first-choice treatment for insomnia?
Its licensed role is restricted to severe insomnia affecting daily life after behavioural and pharmacological alternatives have failed. Sedation, cardiac effects, dependence and uncertainty about prolonged exposure also require caution.
Can children take it for insomnia?
Sources
These sources were used to prepare and review this medicine page.
Prepared and reviewed by the iatroX editorial team.