Chloral hydrate was discontinued primarily because safer, more predictable sedatives replaced it, and accumulating reports of serious adverse events, including deaths in pediatric dental settings, made its risk profile unacceptable by modern standards. Though it was one of the oldest sedative drugs in medicine, dating back to the 1800s, manufacturers stopped producing it as hospitals and clinics shifted to alternatives with wider safety margins and fewer complications.
How Chloral Hydrate Works in the Body
Chloral hydrate itself isn’t the active drug. Once swallowed, it’s rapidly converted in the liver into a compound called trichloroethanol, which is the molecule that actually produces sedation. Trichloroethanol enhances the activity of GABA receptors in the brain, the same system that benzodiazepines target, which is why chloral hydrate produces similar calming and sleep-inducing effects. It also reduces the excitability of pain-sensing nerve cells, which may have contributed a mild analgesic benefit.
The problem is that this metabolic conversion isn’t always predictable. How quickly and completely the liver processes chloral hydrate varies from person to person, especially in children and infants whose liver enzymes are still maturing. That unpredictability made dosing a gamble in ways that newer drugs avoid.
Pediatric Deaths in Dental Settings
The most damning evidence against chloral hydrate came from pediatric dentistry. At least 12 deaths of children were documented before, during, or after dental procedures involving chloral hydrate sedation. The causes ranged from dosing errors and outright overdoses to dangerous drug combinations and improper patient monitoring.
Some cases were devastating in their preventability. In one, a 13-year-old received a massive overdose and died of respiratory arrest. In another, a 4-month-old was strapped into a restraint board without proper airway positioning, leading to death. A 4-year-old girl was discharged just one hour after sedation, remained drowsy but was sent home, continued to be excessively sleepy for six hours, and died from respiratory arrest that evening. A 2-year-old with a known medical condition stopped breathing, turned blue, and suffered permanent brain damage after being placed in a restraint 50 minutes after receiving the drug.
These cases revealed a pattern: chloral hydrate’s sedation could deepen unpredictably after what appeared to be an adequate recovery period. Children who seemed awake enough to go home could slip back into dangerous sedation, a phenomenon sometimes called “resedation.” That long, unreliable tail of drowsiness set chloral hydrate apart from newer drugs that clear the body more quickly and predictably.
Gastrointestinal Damage
Chloral hydrate is harsh on the stomach. It has a pungent, spicy odor and a bitter taste that made children resist taking it orally. More concerning, it directly irritates the lining of the gastrointestinal tract. Animal studies showed that chloral hydrate produces visible ulcers in the stomach lining within six hours, with the damage peaking at 12 hours. Children commonly experienced nausea and vomiting after receiving it, which created a practical problem during imaging procedures that required the child to remain still, and also raised the risk of aspiration if a sedated child vomited.
Better Alternatives Emerged
The discontinuation of chloral hydrate wasn’t just about its risks. It was also about the arrival of drugs that worked as well or better with fewer complications. Dexmedetomidine, for example, can be given as a nasal spray rather than forced orally. A meta-analysis of seven trials involving over 1,800 children found that intranasal dexmedetomidine outperformed oral chloral hydrate on nearly every measure that matters: higher sedation success rates, faster onset, shorter sedation duration, quicker awakening, and dramatically lower rates of nausea and vomiting.
Dexmedetomidine works through a different mechanism, activating receptors that calm the sympathetic nervous system, which also gives it mild anxiety-reducing effects. Its half-life in the blood is shorter, meaning it clears the body faster and carries less risk of that delayed resedation that made chloral hydrate so dangerous after discharge. The rates of serious cardiovascular side effects like low blood pressure and slow heart rate were statistically similar between the two drugs, meaning dexmedetomidine achieved better results without trading one set of dangers for another.
Benzodiazepines like midazolam also became standard alternatives, particularly for procedural sedation in hospitals. Interestingly, at least one large study of hospitalized infants found that chloral hydrate actually had a lower adverse event rate than midazolam, lorazepam, and pentobarbital. Out of 650 infants, those receiving chloral hydrate had significantly fewer complications. This finding highlights an important nuance: chloral hydrate’s problems weren’t that it was inherently more dangerous than every alternative in every setting. The danger was concentrated in outpatient environments like dental offices, where monitoring was less rigorous and children were sent home while the drug was still active.
The Manufacturing and Regulatory Picture
Chloral hydrate’s exit from the market wasn’t a single dramatic ban. It was a gradual withdrawal driven by converging forces. As reports of pediatric deaths accumulated, professional organizations began recommending against its use. Hospitals developed protocols favoring newer sedatives. With demand shrinking, manufacturers had less financial incentive to keep producing it. The drug was eventually removed from formularies at most institutions, and production ceased.
In the United States, chloral hydrate also carried regulatory baggage as a Schedule IV controlled substance, and its association with “knockout drops” (the infamous “Mickey Finn” slipped into drinks) gave it a cultural stigma that other sedatives didn’t share. When pharmacies stopped stocking it and compounding it became the only option, the practical barriers to using it became another reason clinicians moved on.
Why Some Clinicians Were Reluctant to Let It Go
Despite its flaws, chloral hydrate had genuine strengths that explain why it remained in use for over 150 years. It was inexpensive, easy to administer orally, and reliably produced deep enough sedation for imaging studies and minor procedures. In controlled hospital settings with proper monitoring, its safety record was actually reasonable. The study of 650 infants found an overall adverse event rate of just 6% across all sedatives, and chloral hydrate performed better than the alternatives in that population.
The drug’s downfall was context-dependent. It was most dangerous when given in settings without continuous monitoring, when combined with other sedatives or nitrous oxide, when children were discharged too early, or when doses were calculated incorrectly. Modern sedation protocols address many of these issues regardless of which drug is used, but chloral hydrate’s long and unpredictable duration made it uniquely vulnerable to each of those failure points. By the time safety standards caught up, better options had already taken its place.