Chlorpromazine, sold under the brand name Thorazine, is the only medication the U.S. Food and Drug Administration has ever approved specifically for treating hiccups.1PubMed. Pharmacologic Interventions for Intractable and Persistent Hiccups: A Systematic Review That distinction has held for decades, and no other drug has come close to displacing it in regulatory terms. The practical reality, though, is more complicated than a single FDA label suggests. The evidence base behind chlorpromazine for hiccups is surprisingly thin, the drug carries real side effects, and several alternatives have emerged that many clinicians now prefer in certain situations.
Why Hiccups Sometimes Need a Prescription Drug
Most hiccups vanish on their own within minutes or hours. The kind that sends someone looking up Thorazine is different. Clinicians generally sort hiccups into three categories by duration: a bout (under 48 hours), persistent hiccups (lasting more than 48 hours), and intractable hiccups (lasting more than a month). Persistent and intractable hiccups can disrupt sleep, make eating painful, cause weight loss, and leave people genuinely miserable. In hospitalized patients, they can interfere with wound healing and breathing.
The hiccup itself is a reflex. It involves an afferent pathway (nerves carrying signals inward, including the phrenic nerve, the vagus nerve, and sympathetic nerves), a processing center in the midbrain, and an efferent pathway that sends motor signals to the diaphragm and the muscles between the ribs.2PubMed Central. Neurotransmitters in hiccups Anything that irritates or activates this arc can trigger hiccups, from a distended stomach to brain tumors to certain medications. When the cause is identifiable, treating it directly is always the first move. Chlorpromazine enters the picture when the hiccups persist and simpler measures have failed.
How Chlorpromazine Works Against Hiccups
Chlorpromazine is an antipsychotic, originally developed in the 1950s for psychiatric conditions like schizophrenia. Its usefulness against hiccups was discovered somewhat by accident, as clinicians noticed that patients receiving it for other reasons stopped hiccupping. The drug blocks dopamine receptors in the brain, and it is thought to suppress the central processing component of the hiccup reflex arc, essentially dampening the midbrain’s tendency to fire the reflex. It also has effects on several other neurotransmitter systems, which may contribute to its anti-hiccup action, though the precise mechanism has never been fully pinned down.
The typical dosing regimen starts with oral tablets at 25 to 50 mg taken three to four times a day. If the hiccups persist after two to three days on oral treatment, an intramuscular injection of 25 to 50 mg may be given. For cases that still do not respond, a slow intravenous infusion of 25 to 50 mg diluted in saline has been used as a last resort.3PubMed. Chlorpromazine The stepped approach reflects how seriously clinicians take the drug’s side-effect profile: you start with the least invasive route and escalate only if needed.
The Evidence Problem
Here is where chlorpromazine’s story gets awkward. Despite being the only FDA-approved treatment, the drug has never been tested against a placebo in a proper randomized controlled trial for hiccups. Its approval rests on older observational data and case reports rather than the kind of rigorous evidence modern medicine demands. A Cochrane systematic review looking for randomized trials of any pharmacological intervention for persistent and intractable hiccups found zero qualifying studies. The only trials that met inclusion criteria involved acupuncture techniques, and even those had a high risk of bias.4PubMed Central. Interventions for treating persistent and intractable hiccups in adults
That does not mean chlorpromazine does not work. Observational data consistently suggest it is effective, and a systematic comparative review found that hiccups completely resolved in patients treated with oral and intramuscular chlorpromazine at doses of 10 to 25 mg.5PubMed Central. A Systematic Comparative Review of Antipsychotic Efficacy and Safety in the Treatment of Hiccups A separate systematic review also characterized chlorpromazine as effective based on available observational data.6PubMed. Systemic review: the pathogenesis and pharmacological treatment of hiccups But “it seems to work based on decades of clinical experience” is a different level of confidence than “it was tested head-to-head against a placebo in hundreds of patients.” For a drug with significant side effects, that gap matters.
Side Effects and Safety Concerns
Chlorpromazine is not a gentle drug. It was designed to manage severe psychiatric illness, and its side-effect profile reflects that. Sedation is common, sometimes pronounced. The drug can cause a significant drop in blood pressure, particularly with intravenous or intramuscular use, which is why those routes are reserved for stubborn cases. Movement-related side effects, including restlessness, muscle stiffness, and involuntary movements, are a well-known hazard of antipsychotic medications in general.
Older adults face particular risks. A case report described an 80-year-old man whose intractable hiccups resolved with chlorpromazine, but who then developed slurred speech and drowsiness severe enough to mimic a stroke. The symptoms disappeared once the drug was stopped.7Journal of Health and Rehabilitation Research. Chlorpromazine-Induced Neurological Symptoms Mimicking Stroke in an Elderly Patient with Intractable Hiccups: A Case Report That kind of reaction is not universal, but it highlights why clinicians think carefully before prescribing chlorpromazine, especially in older or medically fragile patients. A 1996 review put the situation plainly: the only approved drug for hiccups may not be acceptable for every patient.8Pharmacotherapy: The Journal of Human Pharmacology and Drug Therapy. Hiccups: A Treatment Review
For someone who needs short-term treatment of a hiccup episode, a few days of chlorpromazine may be tolerable. But intractable hiccups can last weeks, months, or even years. Long-term chlorpromazine use carries the risk of tardive dyskinesia, a condition involving involuntary repetitive movements that can become permanent. That risk alone makes many clinicians reluctant to keep patients on chlorpromazine for extended courses and pushes them toward alternatives.
Alternatives That Have Gained Ground
Because chlorpromazine’s side effects limit its use, especially long-term, several other medications have carved out roles in hiccup management. None of them are FDA-approved for the indication, but their evidence bases have grown enough that many clinicians now reach for them first in certain scenarios.
Baclofen
Baclofen is a muscle relaxant that acts on receptors in the spinal cord and brain. Case reports and small studies have shown it can resolve chronic hiccups, and some clinicians consider it one of the more reliably effective options.9PubMed. Baclofen, a treatment for chronic hiccup It is generally better tolerated than chlorpromazine for longer courses. A systematic review noted that baclofen is less likely than standard antipsychotic agents to cause side effects during long-term therapy.10PubMed. Systemic review: the pathogenesis and pharmacological treatment of hiccups Drowsiness and dizziness can still occur, and the drug should not be stopped abruptly because withdrawal can cause seizures, but these are manageable concerns compared to the movement-disorder risks of antipsychotics.
Gabapentin
Gabapentin, originally developed for seizures and now widely used for nerve pain, has shown promise in hiccup treatment. In one published case, a patient with persistent hiccups of unknown cause saw episodes drop to under 15 minutes a day after starting gabapentin at 300 mg three times daily, without notable side effects.11PubMed Central. A Case Report on Hiccups Improvement With Gabapentin A case series in palliative care patients also found gabapentin effective for persistent hiccups.12Journal of Cancer Prevention & Current Research. Evaluation of gabapentin efficacy in palliative care persistent hiccups management: case series Like baclofen, gabapentin carries a lower side-effect burden than chlorpromazine during prolonged use, which makes it attractive for patients whose hiccups have been going on for weeks or months.
Metoclopramide
Metoclopramide is an anti-nausea drug that also speeds up stomach emptying, and it has been used for hiccups since the 1970s. An early report found that it induced relief of intractable hiccups in 14 patients with various serious illnesses, with effects appearing within 30 minutes of oral or injectable dosing and lasting up to eight hours.13PubMed. Metoclopramide in hiccup More recently, a multicenter randomized pilot study concluded that metoclopramide appears to be a promising candidate, with mild side effects.14PubMed. Metoclopramide for patients with intractable hiccups: a multicentre, randomised, controlled pilot study It is particularly useful when hiccups stem from gastrointestinal causes like gastric distension, since the drug addresses the underlying trigger. Metoclopramide has its own movement-disorder risks with long-term use, though, so it is typically used for shorter courses.
Other Antipsychotics
Chlorpromazine is not the only antipsychotic that works. The same systematic comparative review that confirmed chlorpromazine’s efficacy also found complete hiccup resolution with haloperidol at 1 to 2 mg, olanzapine at 2.5 to 10 mg, and risperidone at 3 mg.15PubMed Central. A Systematic Comparative Review of Antipsychotic Efficacy and Safety in the Treatment of Hiccups Olanzapine has gotten particular attention as a potentially better-tolerated antipsychotic option. These drugs work through a similar dopamine-blocking mechanism as chlorpromazine but have different side-effect profiles that may make them preferable for specific patients.
Physical Maneuvers Come First
Before any medication enters the conversation, clinicians expect patients to try physical interventions. These are considered first-line treatment for hiccups of any duration.16Journal of Neurocritical Care. Hiccups in neurocritical care The basic idea behind most of them is to interrupt the reflex arc, either by stimulating the vagus nerve, disrupting normal breathing patterns, or counteracting diaphragm irritation.
Familiar examples include breath-holding, the Valsalva maneuver (bearing down as if straining), sipping ice water, gargling, and swallowing a teaspoon of dry granulated sugar. Less familiar ones include pressing gently on the eyeballs (which triggers a vagal reflex), massaging the carotid sinus in the neck, or stimulating the ear canal.17PubMed. Treatment of hiccup by vagal maneuvers These tricks work well for ordinary acute hiccups. For hiccups that have been going on for days or weeks, however, they are mostly ineffective, and that is when pharmacological treatment becomes necessary.
When Your Doctor Might Choose Chlorpromazine Over Alternatives
Given the alternatives available, you might wonder why anyone still uses chlorpromazine for hiccups. The answer comes down to a few practical considerations. First, it remains the only drug with FDA approval for the indication, which gives it a legal and insurance footing that off-label alternatives lack. Some hospital protocols still default to it. Second, it tends to work quickly, particularly when given by injection, which matters in acute care settings where a patient’s hiccups are interfering with something urgent like post-surgical recovery or mechanical ventilation. Third, for short-term use in a monitored setting, the side-effect profile is manageable.
The situations where chlorpromazine makes less sense are equally clear. If the hiccups are likely to require weeks or months of treatment, the long-term risks of an antipsychotic are hard to justify when baclofen or gabapentin may do the job with fewer consequences. If the patient is elderly, the risk of severe sedation, falls, and neurological side effects tips the balance toward gentler alternatives. And if the patient is already taking other medications that interact with antipsychotics, or has conditions like Parkinson’s disease where dopamine blockade is harmful, chlorpromazine is generally avoided.
The Underlying Cause Matters More Than the Drug Choice
One of the most important things to understand about treating persistent hiccups is that the medication is usually a bridge, not a solution. Hiccups that last more than 48 hours frequently have an identifiable cause: gastroesophageal reflux irritating the diaphragm, a tumor pressing on the vagus or phrenic nerve, a metabolic disturbance like kidney failure, a central nervous system problem, or even a medication side effect. When the underlying cause is found and treated, the hiccups often stop without needing any anti-hiccup drug at all.
The workup for persistent hiccups can involve blood tests, imaging of the chest and brain, and a careful medication review. Proton pump inhibitors, for instance, can resolve hiccups caused by acid reflux. Adjusting a chemotherapy regimen can stop hiccups triggered by certain cancer drugs. Chlorpromazine or its alternatives are most valuable when no correctable cause is found or when the hiccups need to be controlled while the underlying problem is being addressed.
Phrenic Nerve Procedures as a Last Resort
For the most extreme cases, where hiccups persist for months or years despite trying multiple medications, more invasive options exist. Phrenic nerve block, which involves injecting anesthetic around the nerve that controls the diaphragm, has been tried as a way to interrupt the reflex arc directly. However, a recent case series of seven patients with intractable hiccups lasting from four months to 13 years found limited or no lasting benefit from phrenic nerve blocks. Some patients experienced initial relief that faded quickly, and one patient’s symptoms actually worsened after the procedure.18PubMed Central. Phrenic Nerve Block for Intractable Hiccups: A Case Series Surgical options like phrenic nerve crushing or severing exist but carry the obvious trade-off of permanently weakening the diaphragm on one side, which affects breathing. These are genuinely last-ditch interventions.
Why the Evidence Has Stayed So Thin
It is worth pausing on a striking fact: hiccups have been a recognized medical problem for centuries, chlorpromazine was approved for them decades ago, and yet the Cochrane reviewers could not find a single qualifying randomized drug trial. Several factors explain this. Persistent and intractable hiccups are relatively rare, which makes it hard to recruit enough patients for a large trial. The condition is also highly variable in its causes and severity, so a study population is inevitably a mix of people with very different underlying problems. Pharmaceutical companies have little financial incentive to fund expensive trials for a condition that already has an approved (and cheap, generic) drug. And the ethical hurdle of giving a placebo to someone with truly intractable hiccups, where the suffering is real and ongoing, complicates trial design.
The result is a field that runs largely on clinical experience, case reports, and small observational studies. Clinicians prescribing chlorpromazine, baclofen, gabapentin, or metoclopramide for hiccups are all, to varying degrees, relying on evidence that would not meet modern standards for most other conditions. That does not mean the treatments are ineffective. It means the confident hierarchies you see in treatment guidelines are built on a thinner foundation than most people assume, and a clinician’s personal experience with what has worked for previous patients carries unusual weight in treatment decisions.
Hiccups Triggered by Medications
An irony worth knowing: some medications can actually cause hiccups as a side effect. Corticosteroids like dexamethasone are among the most common culprits, particularly at higher doses used in cancer treatment. Certain chemotherapy drugs, benzodiazepines, and even some antibiotics have been reported to trigger hiccup bouts. In these cases, the first intervention is not adding chlorpromazine on top but rather adjusting the offending medication if possible. A patient who develops persistent hiccups shortly after starting a new drug should always have that temporal connection flagged and investigated before an anti-hiccup regimen is layered on.
This is also relevant for hospitalized patients receiving opioids, which can slow gut motility and cause the kind of gastric distension that irritates the diaphragm and sets off the reflex. For these patients, metoclopramide can serve double duty by both treating the hiccups and addressing the sluggish stomach that triggered them.