Facebook Pixel Code
Section banner image
Paediatric Laboratory Medicine


Clinical Significance

Chloral hydrate is a sedative and hypnotic drug, also known as trichloroacetaldehyde monohydrate, 2,2,2-trichloro-1,1-ethanediol. It is used for the short-term treatment of insomnia and as a sedative before minor medical or dental treatment. It has been largely displaced by the development of benzodiazepines. It was also formerly used as in veterinary medicine as a general anesthetic. Insomnia is a sleep disorder characterized by an inability to sleep and/or to remain asleep for a reasonable period during the night. Benzodiazepine tablets, the benzodiazepines, are a class of drugs with hypnotic, anxiolytic, anticonvulsant, amnestic and muscle relaxant properties. Anesthesia (AE), also anesthesia (BE), is the process of blocking the perception of pain and other sensations. In therapeutic doses for insomnia it is effective within 60 minutes; it's rapidly metabolized into trichloroethanol and trichloroacetic acid. Higher doses can depress respiration and blood presure. An overdose is marked by confusion, convulsions, nausea, and vomiting, severe drowsiness, slow and irregular breathing, cardiac arrythmia and weakness. It may also cause liver damage. It is moderately addictive. Chronic use can cause dependency and withdrawals symptoms. A solution of chloral hydrate in alcohol is called "knockout drops" known as a Mickey Finn.

Test Name


Alternate Name/ Synonym

Chloral Hydrate, Mickey Finn

Test Code


Drug Class






External Proficiency Testing

KKGT - Netherlands (Association for Quality Assessment in Therapeutic Drug Monitoring and Clinical Toxicology)

Turn Around Time

Daily, Stat

Specimen Type

Serum, Plasma (Heparin, Citrate or EDTA), Urine, Miscellaneous Fluid(s)*

Minimum Specimen Requirements

1.0 mL

Optimal Collection Time

Within 12 hours of ingestion


4°C (transport with a cool pack if possible)

Special Requirements

* Miscellaneous Fluid(s): phone Toxicology Laboratory (416-813-5906) for availability on specific fluid.

Approval is not required

CPT Codes


Shipping and Contact Information

The Hospital for Sick Children
Rapid Response Laboratory
170 Elizabeth Street, Room 3642
Toronto, ON
M5G 2G3
Phone: 416-813-7200
Phone: 1-855-381-3212

Therapeutic Range

Not detected

Critical Values

Serum/Plasma: > 40 mmol/L