This page shows what was measured, who it was measured in, and what that does not settle.
What Chlorpromazine does in the body
Psychosis and schizophrenia, and a long list of other uses including severe nausea, hiccups that will not stop, and agitation
Chlorpromazine blocks the dopamine receptor, which is what reduces hallucinations and delusions, and it was the discovery of that effect in this molecule that produced the whole dopamine theory of psychosis. But it was not designed to do that: it was developed as an antihistamine for surgical anaesthesia, and it blocks a great many other receptors as well. It blocks the adrenaline receptors that hold blood pressure up, the acetylcholine receptors that keep the mouth wet and the gut moving, and the histamine receptors that keep a person awake. The label says the precise mechanism of its therapeutic effect is not known, and that has been true since 1952.
What happened in people
A standardised mean difference of 0.38 against placebo for overall symptom change, twelfth of fifteen ranked antipsychotics
✎ Source-linked record
Where this came from
A person wrote this into the record with the study named beside it. No reviewer has signed it off.
The recorded finding that sits closest to something a person would notice. Written into the record, not signed off, and it carries no population or interval.
United States prescribing information for chlorpromazine hydrochloride — Boxed Warning, Indications and Usage, Clinical Pharmacology, Warnings (Tardive Dyski… · a recorded source, not a stored snapshot
The limit that matters most
That weight gain and sedation are distinctive to second-generation antipsychotics — chlorpromazine's pooled risk ratios are 4.92 and 2.79
Where it acts
Subcortical structures of the central nervous system, per the label, together with adrenergic, cholinergic, histaminergic and serotonergic receptors throughout the body — which is why its adverse effects reach the skin, the eyes, the blood pressure and the gut
Kind of result
Symptoms and quality of life
Supervision
Professional supervision is normally required. A regulator classifies this substance in a way that restricts how it is supplied.
What the registries record it as
The substance registry classes this as chemical.
FDA substance registry · 9WP59609J6 · read 2026-08-29
Where each sentence above came from
No recorded sentence describes the change this makes in a way that stands on its own. The page opens with what it is taken for instead, and the recorded explanation follows below.
Shown as the opening line on this page.
A limit recorded against this substance. Not signed off as a reviewed claim.
The four opening statements run to 149 words.
Words this page uses
Four words worth knowing first
Chosen from what this page shows, with each one explained before the word it depends on.
Comparator
A comparator is whatever the treatment was measured against.
A picture of it, and where the picture fails
It is like the other runner in a race.
Where that stops being true. A race has one winner. A study can show both arms improved.
What people get wrong. Results are read without asking what the other group got. Beating nothing is not beating a treatment.
The control condition against which the experimental intervention is assessed.
Randomisation
Randomisation means chance decides who gets which treatment.
A picture of it, and where the picture fails
It is like a coin toss deciding the groups.
Where that stops being true. A coin toss is fair once. Fairness here comes from doing it for everyone.
What people get wrong. It is thought to make groups identical. It makes them similar on average, including on things nobody measured.
Allocation of participants to arms by a chance process, so that unmeasured factors are balanced in expectation.
Absolute difference
An absolute difference is how many more people in a hundred were affected.
A picture of it, and where the picture fails
It is like counting heads in two rooms of a hundred.
Where that stops being true. Heads are easy to count. Study results carry a margin of error too.
What people get wrong. It is confused with a percentage change, which can look far larger.
The arithmetic difference in event rates between arms.
Confidence interval
A confidence interval is the range the true answer is likely to sit in.
A picture of it, and where the picture fails
It is like a weather forecast giving a range rather than one number.
Where that stops being true. A forecast range covers tomorrow. This one covers what the study could resolve.
What people get wrong. The middle number is read as the answer. A range crossing zero means no change is still possible.
An interval estimate that would contain the true parameter in a stated proportion of repeated studies.
What happened in people◇Read from sources, not yet reviewed
What happened in people
Each card is one study: the exact question it asked, who was in it, and whether it showed what it set out to show.
Death, violent behaviour, overall improvement, relapse and satisfaction with care in schizophrenia and non-affective serious mental illness
✓ The study showed what it set out to show
Who was studied
Cochrane review: chlorpromazine versus placebo for schizophrenia (CD000284)
How many people
1831
Study design
Systematic review and meta-analysis of 55 randomised controlled trials
Compared against
Not recorded for this study
Kind of result
Living longer, or avoiding a major event
What was found
Global improvement risk ratio 0.71 (95% CI 0.58 to 0.86), 1,164 participants in 14 trials; leaving the study early 0.64 (95% CI 0.53 to 0.78), 1,831 participants in 27 trials; relapse over six months to two years 0.65 (95% CI 0.47 to 0.90), 512 participants in 3 trials
Repeated elsewhere
Replicated
What this does not prove. Meeting one endpoint in one population does not carry to other goals or other people.
The limits of this study, and where it came from
Main limit. The reviewers state that the quality of the evidence is very low. Sedation risk ratio 2.79, acute movement disorders 3.47, parkinsonism 2.11, dizziness with lowered blood pressure 2.38, and considerable weight gain 4.92 (95% CI 2.32 to 10.43) on 165 participants across 5 trials. The sample size recorded here is the largest single pooled comparison in the review, not the total across all 55 trials.
How far it carries. This study is recorded from the curated record, not from the registry match.
Form and route. Oral tablet, oral concentrate solution, and intramuscular injection
Interval reported. 95% CI 0
Written into the record, not signed off as a reviewed claim.
United States prescribing information for chlorpromazine hydrochloride — Boxed Warning, Indications and Usage, Clinical Pharmacology, Warnings (Tardive Dyski… · a recorded source, not a stored snapshot
PubChem CID 2726 — chlorpromazine structure, formula and molecular weight (https://pubchem.ncbi.nlm.nih.gov/compound/2726) · a recorded source, not a stored snapshot
Mean overall change in symptoms against placebo in acute schizophrenia, with all-cause discontinuation, weight gain, extrapyramidal effects, prolactin, QTc and sedation as secondary outcomes
✓ The study showed what it set out to show
Who was studied
Leucht 15-drug multiple-treatments meta-analysis
How many people
43049
Study design
Bayesian network meta-analysis of 212 blinded randomised trials
Compared against
Not recorded for this study
Kind of result
A number that stands in for health
What was found
Chlorpromazine standardised mean difference 0.38 (95% CrI 0.23 to 0.54), twelfth of fifteen and above lurasidone and iloperidone at 0.33 each
Repeated elsewhere
Replicated
What this does not prove. Meeting one endpoint in one population does not carry to other goals or other people.
The limits of this study, and where it came from
Main limit. Chlorpromazine has the widest credible interval of the fifteen drugs, reflecting how much of its randomised evidence predates modern trial methods.
How far it carries. This study is recorded from the curated record, not from the registry match.
Form and route. Oral tablet, oral concentrate solution, and intramuscular injection
Interval reported. Not recorded in this summary
Written into the record, not signed off as a reviewed claim.
United States prescribing information for chlorpromazine hydrochloride — Boxed Warning, Indications and Usage, Clinical Pharmacology, Warnings (Tardive Dyski… · a recorded source, not a stored snapshot
PubChem CID 2726 — chlorpromazine structure, formula and molecular weight (https://pubchem.ncbi.nlm.nih.gov/compound/2726) · a recorded source, not a stored snapshot
What we know
RNAWiki holds 2 written-up human studies for this substance, each with the question it asked.
How we know it
Each card names the study, the number of people and what the study set out to measure.
What this does not prove
These summaries were written by a person and have not been signed off as reviewed claims.
Why it matters
A study that failed is as informative as one that worked, and both are here.
What we still do not know
No reviewed claim exists, so no exact population, effect size or interval is published yet.
What it changes in the body◇Read from sources, not yet reviewed
The path through the body
From what a person takes to what changes. A solid line is a step measured in people. A dashed line is a step nobody has measured that way.
Start
Chlorpromazine
What a person takes: Oral tablet, oral concentrate solution, and intramuscular injection.
The measurement behind this step
There is no long-acting depot. Oral bioavailability is low and variable because of extensive first-pass metabolism, which is why oral and injectable amounts differ so much. Phenothiazine solutions oxidise on exposure to light and air and the label instructs that discoloured solutions not be used. Contact dermatitis has been reported in nursing staff handling the liquid and injectable forms, and the label recommends rubber gloves for administration.
Getting in
A tablet, a liquid concentrate, or an injection into muscle
Chlorpromazine comes as a tablet, an oral concentrate and an injectable solution. There is no long-acting depot form.
╌╌Described, with no measurement named. No measurement is named for this step, so it is drawn as an unconfirmed link.
The measurement behind this step
Oral bioavailability is low and variable because of extensive first-pass metabolism, which is one reason the injectable amount differs so markedly from the oral one. Phenothiazine solutions oxidise on exposure to light and air, and the label instructs that discoloured solutions not be used.
United States prescribing information for chlorpromazine hydrochloride — Boxed Warning, Indications and Usage, Clinical Pharmacology, Warnings (Tardive Dyski… · a recorded source, not a stored snapshot
Reaching the cell
It reaches the brain and dozens of receptors on the way
The drug crosses into the brain and also acts throughout the body, because the receptors it binds are not confined to the nervous system.
╌╌Described, with no measurement named. No measurement is named for this step, so it is drawn as an unconfirmed link.
The measurement behind this step
The label describes actions at all levels of the central nervous system, primarily at subcortical levels, as well as on multiple organ systems. Metabolism is hepatic and extensive, producing more than a dozen metabolites including 7-hydroxychlorpromazine, which is itself active, and chlorpromazine sulfoxide, which is not.
United States prescribing information for chlorpromazine hydrochloride — Boxed Warning, Indications and Usage, Clinical Pharmacology, Warnings (Tardive Dyski… · a recorded source, not a stored snapshot
What it acts on
It blocks dopamine, and this is where the dopamine theory came from
Blocking the dopamine receptor is what reduces hallucinations and delusions. That was not known when the drug was introduced; it was worked out afterwards, and the idea that psychosis involves dopamine came from working it out.
╌╌Described, with no measurement named. No measurement is named for this step, so it is drawn as an unconfirmed link.
The measurement behind this step
D2 antagonism is the accepted basis of the antipsychotic effect, and blockade in the chemoreceptor trigger zone is the basis of the antiemetic effect that gives the drug its nausea and hiccup indications. The label nonetheless states the precise mechanism of the therapeutic effect is not known.
United States prescribing information for chlorpromazine hydrochloride — Boxed Warning, Indications and Usage, Clinical Pharmacology, Warnings (Tardive Dyski… · a recorded source, not a stored snapshot
The change it makes
And it blocks adrenaline, acetylcholine, histamine and serotonin too
The same molecule blocks the receptors that hold blood pressure up, keep the mouth wet and the gut moving, and keep a person awake. That is where almost all of its side effects come from.
╌╌Described, with no measurement named. No measurement is named for this step, so it is drawn as an unconfirmed link.
The measurement behind this step
The label describes strong antiadrenergic and weaker peripheral anticholinergic activity, relatively slight ganglionic blockade, and slight antihistaminic and antiserotonin activity. Alpha-1 blockade produces the orthostatic hypotension measured in the Cochrane review at a risk ratio of 2.38; H1 and 5-HT2C blockade is the standard explanation for sedation at 2.79 and weight gain at 4.92; muscarinic blockade produces dry mouth, constipation, urinary retention and adynamic ileus, all listed in the label.
United States prescribing information for chlorpromazine hydrochloride — Boxed Warning, Indications and Usage, Clinical Pharmacology, Warnings (Tardive Dyski… · a recorded source, not a stored snapshot
What that does for a person
Psychosis improves, and over years the skin and eyes record the exposure
Symptoms improve, on the evidence of 55 trials. Over years at high amounts, sun-exposed skin can turn slate grey and fine deposits can form in the lens and cornea.
╌╌Described, with no measurement named. No measurement is named for this step, so it is drawn as an unconfirmed link.
The measurement behind this step
Global improvement risk ratio 0.71 (95% CI 0.58 to 0.86) against placebo. Standardised mean difference 0.38 (95% CrI 0.23 to 0.54), twelfth of fifteen. Skin pigmentation after three years or more at 500 to 1,500 mg daily; lens and corneal deposits after two years or more at 300 mg daily and higher, with the label noting the nature of the deposits has not yet been determined.
United States prescribing information for chlorpromazine hydrochloride — Boxed Warning, Indications and Usage, Clinical Pharmacology, Warnings (Tardive Dyski… · a recorded source, not a stored snapshot
No suggested links are held for this record, so nothing is hidden from this path.
What we know
The record describes 5 steps from taking it to an effect in a person.
How we know it
Each step names the study behind it in the technical detail beside it.
What this does not prove
A change inside the body is a reason to look. It is not a result in a person.
Why it matters
A reader can see exactly where the chain stops being measured in people.
What we still do not know
No reviewed claim binds any of these steps to a named population.
What is missing or unclear◇Read from sources, not yet reviewed
Were people like you studied?
RNAWiki cannot tell whether a study fits you. It can show who was in it, and where the result stops carrying.
Who was studied
People similar to this profile were included.
People with schizophrenia and acute psychosis, particularly where cost or availability rules out anything newer; and people with severe nausea, vomiting or intractable hiccups, which is what a large share of current use is actually for.
Who is missing from the studies
Which groups were under-represented in the studies has not been recorded for this substance. Pregnancy, breastfeeding, children, older adults, and people with liver or kidney conditions are commonly excluded from trials; nothing here says whether they were.
What the label states about particular groups
On people who are pregnant, the label states: “Usage in Pregnancy Safety for the use of chlorpromazine during pregnancy has not been established.”
US prescribing information · 41b86f9d-d7e2-4296-8d88-e8257c7cbed2 · read 2026-08-30
On people who are breastfeeding, the label states: “There is evidence that chlorpromazine is excreted in the breast milk of nursing mothers.”
US prescribing information · 41b86f9d-d7e2-4296-8d88-e8257c7cbed2 · read 2026-08-30
Where the result stopped carrying
The Cochrane reviewers graded the quality of the whole 55-trial evidence base as very low
No difference in relapse rates was found in the short, medium or long term over two years, and the six-month-to-two-year finding was heterogeneous
Two twenty-first-century antipsychotics, lurasidone and iloperidone, rank below this 1950s drug on pooled symptom reduction
This is a scope explorer, not a diagnosis engine.
It shows who was studied so you can see whether people similar to you were included.
RNAWiki cannot tell whether a study fits you. It can show who was in it.
What it would be like to take◇Read from sources, not yet reviewed
Why it might seem to do nothing
A real effect and a noticed effect are different things. These are the recorded reasons the two come apart.
It was studied in different people
The people in the studies were not much like the reader.
On this record: Which groups were under-represented in the studies has not been recorded for this substance. Pregnancy, breastfeeding, children, older adults, and people with liver or kidney conditions are commonly excluded from trials; nothing here says whether they were.
The evidence may simply be wrong
Small early studies often do not hold up.
On this record: RNAWiki has not yet published a reviewed conclusion for this use.
Other reasons RNAWiki checked and found nothing for (11)
It was studied for a different goal
The studies measured something else entirely. Nothing in this record points to this reason.
A different form was studied
The studied form is not the form on the shelf. Nothing in this record points to this reason.
There was nothing to correct
Where a level is already normal, topping it up may change nothing. Nothing in this record points to this reason.
Something else had to happen too
In the studies it was paired with training, a diet or another treatment. Nothing in this record points to this reason.
The change is too small to feel
A real change can still sit below what a person notices. Nothing in this record points to this reason.
Day-to-day swing hides it
Sleep, food, stress and time of day move most numbers more than this would. Nothing in this record points to this reason.
Not enough time yet
The studies ran longer than the person has waited. Nothing in this record points to this reason.
It was not taken as studied
Missed days change the result, and studies count them. Nothing in this record points to this reason.
Something else changed at the same time
Two changes at once cannot be told apart afterwards. Nothing in this record points to this reason.
The product may not be what it says
Contents of a sold product are not always what the label states. Nothing in this record points to this reason.
No recorded reason
RNAWiki has nothing stored that would explain it. Nothing in this record points to this reason.
None of these is a reason to take more. Taking more is not a step this page ever suggests.
What it would be like to take◇Read from sources, not yet reviewed
What taking it involves
The recorded facts about getting hold of it and using it. Nothing here is a suggestion about what you should do.
How it is supplied
Given by a clinician
❝ Quoted from a source
Where this came from
Copied from a source RNAWiki stored, with the source named.
Read from the recorded approval status.
No source is stored against this line.
Form and route
Oral tablet, oral concentrate solution, and intramuscular injection
✎ Source-linked record
Where this came from
A person wrote this into the record with the study named beside it. No reviewer has signed it off.
The form and route recorded on this substance.
No source is stored against this line.
Who oversees it
Professional supervision is normally required. A regulator classifies this substance in a way that restricts how it is supplied.
❝ Quoted from a source
Where this came from
Copied from a source RNAWiki stored, with the source named.
Suppression classes recorded: S6.
No source is stored against this line.
What is in the pack
There is no long-acting depot. Oral bioavailability is low and variable because of extensive first-pass metabolism, which is why oral and injectable amounts differ so much. Phenothiazine solutions oxidise on exposure to light and air and the label instructs that discoloured solutions not be used. Contact dermatitis has been reported in nursing staff handling the liquid and injectable forms, and the label recommends rubber gloves for administration.
✎ Source-linked record
Where this came from
A person wrote this into the record with the study named beside it. No reviewer has signed it off.
Recorded notes on how this is sold and what that means for what is in the pack.
No source is stored against this line.
Where it is registered
Regulatory records are listed in the technical disclosure at the foot of this page.
# Counted from records
Where this came from
A count of rows RNAWiki holds. It describes our records, not your body.
Register entries are stored per jurisdiction and shown with their dates.
No source is stored against this line.
Why people stop
Not recorded.
∅ Nothing recorded
Where this came from
RNAWiki holds nothing here and says so rather than guessing.
No record of why people stopped taking it is stored for this substance.
No source is stored against this line.
What it would be like to take◇Read from sources, not yet reviewed
What can go wrong
Sorted by where each line came from. A regulator's label and a report somebody sent in are not the same kind of fact.
·Worth asking a clinician aboutWritten into the record from the studies named on this page
The United States label carries a boxed warning for increased mortality in elderly patients with dementia-related psychosis, and states the supporting trials were largely of atypical antipsychotics. Tardive dyskinesia is described as potentially irreversible with prevalence highest among the elderly, especially elderly women, and the label states it is unknown whether antipsychotic products differ in their potential to cause it. Sedation, orthostatic hypotension, acute dystonia and parkinsonism are the characteristic acute effects. Long-term therapy carries skin pigmentation and ocular deposits in the lens and cornea. Photosensitivity, exfoliative dermatitis, seizures, agranulocytosis, jaundice, neuroleptic malignant syndrome, priapism and adynamic ileus are all in the label, as is a caution against use in children and adolescents with signs suggesting Reye syndrome.
Nobody counted how many people took this and were fine, so this cannot be turned into a rate.
United States prescribing information for chlorpromazine hydrochloride — Boxed Warning, Indications and Usage, Clinical Pharmacology, Warnings (Tardive Dyski… · a recorded source, not a stored snapshot
Over a long time. No completed tested study window is recorded, so long-term effects are not established by the registry record.
Groups the studies covered thinly. Which groups were under-represented in the studies has not been recorded for this substance. Pregnancy, breastfeeding, children, older adults, and people with liver or kidney conditions are commonly excluded from trials; nothing here says whether they were.
What is missing or unclear◇Read from sources, not yet reviewed
Does the exact form matter?
Evidence belongs to the exact thing that was tested. A different salt, a different mixture or a different preparation is a different question.
The form that was studied
Oral tablet, oral concentrate solution, and intramuscular injection
✎ Source-linked record
Where this came from
A person wrote this into the record with the study named beside it. No reviewer has signed it off.
The form used in the studies cited on this page.
No source is stored against this line.
What is sold
Oral bioavailability is low and variable because of extensive first-pass metabolism, which is why oral and injectable amounts differ so much. Phenothiazine solutions oxidise on exposure to light and air and the label instructs that discoloured solutions not be used. Contact dermatitis has been reported in nursing staff handling the liquid and injectable forms, and the label recommends rubber gloves for administration.
✎ Source-linked record
Where this came from
A person wrote this into the record with the study named beside it. No reviewer has signed it off.
Recorded notes on which forms are sold and how they compare.
No source is stored against this line.
What is recorded as being sold
138 products list this as an active ingredient in the United States drug directory. 136 of them contain it and nothing else.
FDA National Drug Code directory · 71656-101 · read 2026-08-29
They are sold as concentrate, injection, liquid, powder, tablet and tablet, coated, taken intramuscular and oral.
FDA National Drug Code directory · 71656-101 · read 2026-08-29
The regulator's established pharmacologic class for it is phenothiazine [epc] and phenothiazines [cs].
FDA National Drug Code directory · 71656-101 · read 2026-08-29
46 published labels name it as an active ingredient. 44 of them describe this substance alone, which is where its own label text on this page comes from.
US prescribing information · 41b86f9d-d7e2-4296-8d88-e8257c7cbed2 · read 2026-08-29
Those labels are classed as human otc drug and human prescription drug.
US prescribing information · 41b86f9d-d7e2-4296-8d88-e8257c7cbed2 · read 2026-08-29
1 marketed supplement label lists this ingredient, classed as other combinations.
Those labels carry all other, nutrient and structure/function claims. A claim of that kind is written by the manufacturer and is not assessed by any regulator, so its presence says nothing about whether it is true.
Chlorpromazine Hydrochloride is oral at HOW SUPPLIED Chlorpromazine Hydrochloride Tablets, USP, 50 mg are round, white film coated tablets, imprinted on one side with "832" above "50" and no print on the reverse side., recorded as fda label in effect 2026-08-14 in the United States.
US prescribing information · 41b86f9d-d7e2-4296-8d88-e8257c7cbed2 · read 2026-08-30
Recorded price in US: 0.23898–0.68534 USD per one unit as the pricing file counts it — a tablet, capsule, patch or single item, across 86 priced products whose strengths and pack forms differ, as of 2026-08-26, paid by retail pharmacies buying the product, as surveyed by the Centers for Medicare & Medicaid Services. It is not a list price, an insurance price, or what anyone pays at a counter..
Recorded source · 2026-08-26 · read 2026-08-28
Evidence carries across two names for one substance. It does not carry across a salt, a mirror form or a mixture.
What it would be like to take◇Read from sources, not yet reviewed
What you could measure
This one is decided with a clinician, so this section holds questions to ask rather than a plan to run.
Self-experiment planning is not offered for a prescription or clinician-supervised medicine. The questions below are for a clinician or pharmacist.
Questions worth asking
Which of the trials of Chlorpromazine studied people like me?
What was measured, and for how long?
Was the result a laboratory value or a health outcome?
What would we watch for, and when would we stop?
Tracking can show whether something changed for you. It cannot show what caused it.
RNAWiki records evidence. It does not say whether this substance is right for you.
What is missing or unclear◇Read from sources, not yet reviewed
Claims that go past the evidence
Things said about this substance that sound reasonable, and the exact step that is missing between the evidence and the claim.
✗Goes past the evidence
That weight gain and sedation are distinctive to second-generation antipsychotics — chlorpromazine's pooled risk ratios are 4.92 and 2.79
Why it sounds right. It follows from something real on this page: a body step, an animal result or a related finding.
The missing step. Nobody measured this in people for this use, or the study that did measure it did not show it.
What would change this
A study in people, for this exact use, measuring this exact thing, that a reviewer signs off.
RNAWiki has not yet published a reviewed conclusion for this use.
✗Goes past the evidence
That the breadth of its label reflects breadth of demonstrated effect — it reflects the evidence standards in force when each indication was added
Why it sounds right. It follows from something real on this page: a body step, an animal result or a related finding.
The missing step. Nobody measured this in people for this use, or the study that did measure it did not show it.
What would change this
A study in people, for this exact use, measuring this exact thing, that a reviewer signs off.
RNAWiki has not yet published a reviewed conclusion for this use.
✗Goes past the evidence
That dopamine excess causes psychosis — the hypothesis was reverse-engineered from this drug's observed effect
Why it sounds right. It follows from something real on this page: a body step, an animal result or a related finding.
The missing step. Nobody measured this in people for this use, or the study that did measure it did not show it.
What would change this
A study in people, for this exact use, measuring this exact thing, that a reviewer signs off.
RNAWiki has not yet published a reviewed conclusion for this use.
✗Goes past the evidence
That the dementia mortality warning rests on randomised evidence for this drug — the label states the trials were largely of atypical antipsychotics
Why it sounds right. It follows from something real on this page: a body step, an animal result or a related finding.
The missing step. Nobody measured this in people for this use, or the study that did measure it did not show it.
What would change this
A study in people, for this exact use, measuring this exact thing, that a reviewer signs off.
RNAWiki has not yet published a reviewed conclusion for this use.
What is missing or unclear◇Read from sources, not yet reviewed
What nobody knows yet
Open questions, each with why it is open and what would close it.
Missing populations
Which groups were under-represented in the studies has not been recorded.
Why it matters. Recorded by the evidence model as a gap on this record.
What would answer it
A study that measures it, and a reviewer to sign it off.
Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.
Missing long-term data
No completed tested study window is recorded.
Why it matters. Recorded by the evidence model as a gap on this record.
What would answer it
A study that measures it, and a reviewer to sign it off.
Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.
No reviewed conclusion
RNAWiki has not yet published a reviewed conclusion for this use.
Why it matters. Recorded by the evidence model as a gap on this record.
What would answer it
A study that measures it, and a reviewer to sign it off.
Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.
Missing interaction studies
No interaction was found in the registers checked. Not finding one is not the same as showing there is none.
Why it matters. Recorded by the evidence model as a gap on this record.
What would answer it
A study that measures it, and a reviewer to sign it off.
Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.
Formulation uncertainty
Several salts, forms or products of Chlorpromazine are recorded. Results from one form may not transfer to another.
Why it matters. Recorded by the evidence model as a gap on this record.
What would answer it
A study that measures it, and a reviewer to sign it off.
Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.
Mechanism not reviewed
No reviewed mechanism story exists for this substance.
Why it matters. Recorded by the evidence model as a gap on this record.
What would answer it
A study that measures it, and a reviewer to sign it off.
Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.
What happened in people◇Read from sources, not yet reviewed
Check any of this yourself
Every line above traced back to the study it came from. This is the technical layer, and the vocabulary changes here.
Every line above can be traced to the study named beside it. Follow the link and read it.
Fifty-five randomised trials, and the evidence graded very low
In plain words
The Cochrane review of chlorpromazine against placebo pooled 55 randomised trials. It found the drug works. It also states in its own results section that the quality of the evidence is very low.
What was measured
Risk ratio 0.71 (95% CI 0.58 to 0.86) for global improvement against placebo, on evidence the reviewers graded very low
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
Adams and colleagues inspected over 1,100 electronic records and included 55 randomised trials, excluding 315. Chlorpromazine produced a global improvement in symptoms and functioning against placebo, risk ratio 0.71 (95% CI 0.58 to 0.86) across 1,164 participants in 14 trials. Fewer people allocated to chlorpromazine left trials early, risk ratio 0.64 (95% CI 0.53 to 0.78) across 1,831 participants in 27 trials. It reduced the number of participants relapsing over six months to two years, risk ratio 0.65 (95% CI 0.47 to 0.90) across 512 participants in 3 trials, though the reviewers note the data were heterogeneous and that no difference was found in relapse rates in the short, medium or long term over two years. The reviewers' verdict on the whole body of evidence is that its quality is very low, and their conclusion is that chlorpromazine is "a well-established but imperfect treatment" whose benchmark position is not threatened by their findings. Half a century of use and 55 trials produced a very-low-quality evidence base, which is a fact about how this field ran its trials rather than about this molecule.
Written into the record, not signed off as a reviewed claim
A weight-gain risk ratio of 4.92, in a drug the class story calls metabolically clean
In plain words
Second-generation antipsychotics are described as the ones that cause weight gain. In the Cochrane review, chlorpromazine — a 1950s drug — had a nearly five-fold risk ratio for considerable weight gain against placebo.
What was measured
That weight gain and metabolic disturbance are distinctive to second-generation antipsychotics — the pooled risk ratio for considerable weight gain with chlorpromazine is 4.92
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
The Cochrane review reports considerable weight gain at a risk ratio of 4.92 (95% CI 2.32 to 10.43) across 165 participants in 5 trials, alongside clear sedation at 2.79 (95% CI 2.25 to 3.45) in 1,627 participants across 23 trials, acute movement disorders at 3.47 (95% CI 1.50 to 8.03), parkinsonism at 2.11 (95% CI 1.59 to 2.80), and lowered blood pressure with dizziness at 2.38 (95% CI 1.74 to 3.25). Akathisia did not occur more often than on placebo. The weight-gain figure rests on only 165 participants and its confidence interval is wide, so the point estimate should not be over-read — but the direction is unambiguous and it sits awkwardly beside a generational story in which metabolic effects arrived with the atypicals. Chlorpromazine's receptor profile predicts it: heavy histamine H1 and 5-HT2C blockade is the same combination that drives weight gain with olanzapine and quetiapine.
Written into the record, not signed off as a reviewed claim
Twelfth of fifteen, and still above two drugs approved fifty years later
In plain words
When 212 trials were pooled, chlorpromazine came twelfth of fifteen antipsychotics on symptom reduction — behind most of the modern drugs, but ahead of lurasidone and iloperidone, both approved in 2009 and 2010.
What was measured
Standardised mean difference against placebo for overall symptom change: 0.38 (95% CrI 0.23 to 0.54), twelfth of fifteen
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
In the Leucht multiple-treatments meta-analysis of 212 blinded trials and 43,049 participants, chlorpromazine's standardised mean difference against placebo for overall symptom change was 0.38 (95% CrI 0.23 to 0.54). That places it twelfth, level with asenapine at 0.38, marginally below ziprasidone and sertindole at 0.39, and above lurasidone and iloperidone at 0.33 each. Its confidence interval is the widest of the fifteen, reflecting how much of its trial evidence predates modern methods. The authors concluded that their findings challenge the straightforward classification of antipsychotics into first-generation and second-generation groupings, and chlorpromazine sitting above two twenty-first-century drugs is one of the clearest illustrations of what they meant.
Written into the record, not signed off as a reviewed claim
A label that still indicates it for hyperactive children as young as one
In plain words
The current United States label lists, among its approved uses, severe behavioural problems in children aged one to twelve, and short-term treatment of hyperactive children with impulsivity, difficulty sustaining attention and poor frustration tolerance.
What was measured
That the breadth of chlorpromazine's label reflects breadth of demonstrated effect — it reflects the evidence standards in force when each indication was added
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
The Indications and Usage section reads, verbatim: "For the treatment of severe behavioral problems in children (1 to 12 years of age) marked by combativeness and/or explosive hyperexcitable behavior (out of proportion to immediate provocations), and in the short-term treatment of hyperactive children who show excessive motor activity with accompanying conduct disorders consisting of some or all of the following symptoms: impulsivity, difficulty sustaining attention, aggressivity, mood lability and poor frustration tolerance." The symptom list in the second half is a description of what would today be diagnosed as attention-deficit hyperactivity disorder. The same section indicates the drug for nausea and vomiting, restlessness before surgery, acute intermittent porphyria, adjunctive treatment of tetanus, mania and intractable hiccups. None of this reflects the evidence standard a new indication would face now; it reflects a label that has been amended rather than rewritten since the 1950s. An indication surviving on a label is not the same as an indication supported by evidence a regulator would accept today.
Source
United States prescribing information for chlorpromazine hydrochloride, Indications and Usage, via the openFDA drug label endpoint
Role in the trial
Not matched to a registered study
Identity check
no open identity hold
Audit mark
contested
Review state
Written into the record, not signed off as a reviewed claim
Skin that turns slate grey and deposits in the lens of the eye
In plain words
After years of treatment at high amounts, chlorpromazine can turn sun-exposed skin a slate-grey colour with a violet tinge, and can deposit fine particles in the lens and cornea of the eye.
What was measured
Skin pigmentation after three years or more at 500 to 1,500 mg daily; ocular deposits after two years or more at 300 mg daily and higher
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
The label records rare instances of skin pigmentation in patients, primarily female, who received the drug usually for three years or more at 500 to 1,500 mg daily, with changes restricted to exposed areas of the body ranging from almost imperceptible darkening to a slate-grey colour, sometimes with a violet hue. Ocular changes are described as occurring more frequently than skin pigmentation, in patients treated usually for two years or more at 300 mg daily and higher, characterised by deposition of fine particulate matter in the lens and cornea, with star-shaped opacities in the anterior lens in more advanced cases, and with epithelial keratopathy and pigmentary retinopathy also reported. A small number of patients with more severe ocular changes had some visual impairment, and the label notes the lesions may regress after withdrawal. It also states that the nature of the eye deposits has not yet been determined. These are visible, physical, cumulative changes of a kind no modern antipsychotic produces, and they are dose- and duration-related.
Source
United States prescribing information for chlorpromazine hydrochloride, Adverse Reactions — Special Considerations in Long-Term Therapy, via the openFDA drug label endpoint
Role in the trial
Not matched to a registered study
Identity check
no open identity hold
Audit mark
caution
Review state
Written into the record, not signed off as a reviewed claim
The dopamine theory of psychosis was reverse-engineered from this molecule
In plain words
Chlorpromazine was not designed to block dopamine. It was developed as an antihistamine for surgery, found by observation to calm psychosis, and only later discovered to block dopamine — after which dopamine was proposed as the cause of psychosis.
What was measured
That dopamine excess causes psychosis — the hypothesis was constructed from the observation that a drug which blocks dopamine reduces symptoms, which is a claim about the drug before it is a claim about the illness
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
The label still states that the precise mechanism by which the therapeutic effects of chlorpromazine are produced is not known, and describes its actions as psychotropic, sedative and antiemetic, with strong antiadrenergic and weaker peripheral anticholinergic activity, slight ganglionic blockade and slight antihistaminic and antiserotonin activity. The historical sequence matters for reading everything downstream of it: the drug came first, the receptor finding came second, and the disease theory came third. A theory derived from what a drug does is a hypothesis about the drug before it is a hypothesis about the illness, and the dopamine hypothesis of schizophrenia has carried that inheritance ever since. Every mechanism section on this site that says a drug's effect "could be mediated through" dopamine D2 antagonism is a descendant of an observation made in a French surgical ward in 1952.
Source
United States prescribing information for chlorpromazine hydrochloride, Clinical Pharmacology, via the openFDA drug label endpoint
Role in the trial
Not matched to a registered study
Identity check
no open identity hold
Audit mark
caution
Review state
Written into the record, not signed off as a reviewed claim
It carries the same dementia boxed warning built on trials of other drugs
In plain words
Chlorpromazine carries the boxed warning about increased deaths in elderly people with dementia. The seventeen trials behind it were largely trials of newer drugs, and the label says so.
What was measured
Death in about 4.5% of drug-treated patients against about 2.6% on placebo across seventeen dementia trials, largely of atypical antipsychotics
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
The boxed warning states that analyses of seventeen placebo-controlled trials of modal duration ten weeks, "largely in patients taking atypical antipsychotic drugs," found a risk of death 1.6 to 1.7 times that of placebo, about 4.5% against about 2.6% over a typical trial, with most deaths cardiovascular or infectious. It adds that observational studies suggest conventional antipsychotic drugs may increase mortality similarly, and that the extent to which those observational findings can be attributed to the drug rather than to patient characteristics is not clear. So for chlorpromazine specifically the randomised evidence for the warning does not exist, and the label is explicit about that. Applying a class warning across a class on the basis of shared mechanism is a defensible regulatory decision and it is an inference, and the label distinguishes the two more clearly than most secondary sources do.
Source
United States prescribing information for chlorpromazine hydrochloride, Boxed Warning, via the openFDA drug label endpoint
Role in the trial
Not matched to a registered study
Identity check
no open identity hold
Audit mark
verified
Review state
Written into the record, not signed off as a reviewed claim
Where else this substance is registered
FDA substance identifier (UNII)
9WP59609J6
RxNorm concept
991039
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What is missing or unclear◇Read from sources, not yet reviewed
How this medicine reached us
Kept near the foot of the page. A historical event moves up only when it changes something about this substance today.
What the approval register records
84 approved applications cover products containing this substance. The earliest was NDA011120, approved 19570918 to GLAXOSMITHKLINE.
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What is not here
7 questions this page could not answer
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The older medicine-wide conclusion held in this record
Written for a clinical reader, and about the medicine as a whole rather than about one indication, population and set of trials. RNAWiki does not treat it as a programme conclusion and no reviewer has signed it off in that form. It is here word for word because it is what the record holds.
The first antipsychotic, which in a Cochrane review of 55 randomised trials produced global improvement against placebo at a risk ratio of 0.71 on evidence the reviewers graded very low, ranked twelfth of fifteen antipsychotics on pooled symptom reduction and still above lurasidone and iloperidone, carries a weight-gain risk ratio of 4.92 that contradicts the usual first-generation story, and holds a United States label listing tetanus, porphyria, intractable hiccups and hyperactive one-year-olds among its approved uses.
Which 7 trials of Chlorpromazine posted no result?
Posted no result
7 of 7 completed trials
Registrations
NCT02810782, NCT01404364, NCT02582736, NCT00202293, NCT02600741 and NCT06154434, and 1 more
Completion dates
oldest 2007-12; newest 2024-07-28
Show the evidence
Trial
NCT02810782
2007-12
NCT01404364
2010-12
NCT02582736
2012-12
NCT00202293
2015-11-01
NCT02600741
2018-07-05
NCT06154434
2019-02-12
1 further recorded trialNCT05190315
2024-07-28
Q7
At the median, Chlorpromazine's trials enrolled 70 people — anything larger?
Median enrolment
70
Largest enrolment
725489
Registered trials counted
17
Q8
What do 860 spontaneous reports say about Chlorpromazine — and not say?
These are reports people sent to a regulator. They do not show the medicine caused the reaction. Nobody counted how many people took the medicine and reported nothing. The same event can be reported more than once, and many reports are incomplete. News coverage, lawsuits and new warnings change how often people report. A count is not a rate and not a risk.
Chlorpromazine appears in spontaneous reports to regulators. Across the 10 most-reported reaction terms, 860 reaction mentions were counted: neuroleptic malignant syndrome 162; suicide attempt 94; somnolence 88; aggression 86. FAERS via Open Targets · CHEMBL1713 · 2026-06-24
Show the evidence
neuroleptic malignant syndrome
162
suicide attempt
94
somnolence
88
aggression
86
confusional state
76
sedation
74
4 more recorded rows
agitation
73
insomnia
71
coma
70
drug abuse
66
recorded 2026-06-24 · last checked 2026-09-04
Q9
Which 10 reactions does Chlorpromazine's label not list?
ChEMBL 37 — CC BY-SA 3.0 Unported · ClinicalTrials.gov — US Government work · Open Targets 26.06 — CC0 · mixed register set; per-register licences in docs/specs/corpus-20k-sources.md · openFDA / DailyMed — US Government work
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