Drug interactions
Chloral hydrate + Chlorzoxazone
Severity: Major
Chloral hydrate and Chlorzoxazone: major interaction.
Last updated Sources: UK SmPC
For healthcare professionals — reference only. This page is a brief summary, not medical advice and not a substitute for official labeling or clinical judgement. Always verify before prescribing or dispensing.
Summary
Chloral hydrate is a sedative-hypnotic, and combining it with a centrally acting muscle relaxant can produce deeper sedation and impaired psychomotor function. Excess depression of consciousness and breathing is possible, particularly in older or frail patients.
What this interaction means in plain words
Chloral hydrate and Chlorzoxazone can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for.
Chloral hydrate belongs to Central Nervous System; Chlorzoxazone belongs to Musculoskeletal.
Why it happens
Additive CNS and respiratory depression.
What to do
Avoid the combination where possible; if needed, use the lowest effective doses and monitor sedation level and respiration. Advise against driving and alcohol.
What to ask your pharmacist
- Does the benefit of taking both outweigh the risk in my case?
- Do I need any blood test, ECG or other check while on both?
- What early warning signs should I watch for, and what should I do if they appear?
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References
- Chloral Hydrate 143mg/5ml Oral Solution - SmPC sections 4.3/4.5 (class statement: centrally acting muscle relaxants; "Concomitant use with antipsychotics, hypnotics, anxiolytics/sedatives, antidepressant agents, centrally acting muscle relaxants, narcotic analgesics, anti-epile") — electronic medicines compendium (UK SmPC)
Other interactions of Chlorzoxazone
Other interactions of Chloral hydrate
- Calcium / magnesium / potassium / sodium oxybates + Chloral hydrate Contraindicated
- Chloral hydrate + Sodium oxybate Contraindicated
- Alfentanil + Chloral hydrate Major
- Alprazolam + Chloral hydrate Major
- Amobarbital + Chloral hydrate Major
- Belladonna and opium + Chloral hydrate Major
Frequently asked questions
Can I take Chloral hydrate with Chlorzoxazone?
MediHelp rates the interaction as major. Chloral hydrate and Chlorzoxazone can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for. Chloral hydrate is a sedative-hypnotic, and combining it with a centrally acting muscle relaxant can produce deeper sedation and impaired psychomotor function. Excess depression of consciousness and breathing is possible, particularly in older or frail patients.
How serious is the interaction between Chloral hydrate and Chlorzoxazone?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid the combination where possible; if needed, use the lowest effective doses and monitor sedation level and respiration. Advise against driving and alcohol.
What other medicines interact with Chlorzoxazone?
MediHelp also lists interactions of Chlorzoxazone with, for example, Alfentanil, Alprazolam, Amobarbital. The full list is on the Chlorzoxazone page.
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