This page shows what was measured, who it was measured in, and what that does not settle.
What Phenylpropanolamine does in the body
In the nose that shrinks swollen tissue and clears the airway.
Phenylpropanolamine narrows blood vessels by acting on the same receptors adrenaline uses, and by pushing the body's own noradrenaline out of nerve endings. Everywhere else it raises blood pressure. In a small number of people, the sudden pressure rise appears to be enough to rupture a vessel in the brain.
Why people take it. Formerly sold as a decongestant and non-prescription diet pill.
What happened in people
A case-control study linked diet-pill use in women with bleeding in the brain.
✓ Reviewed first-read answer
Where this came from
A person wrote this and a reviewer approved it against this exact record. It carries no effect size.
A reviewer approved this against this record. The reviewed-claim record carrying the exact population and effect size does not exist yet.
No source is stored against this line.
The limit that matters most
The estimated risk ranged from a modest increase to an extremely large one.
Where it acts
Nasal mucosal vasculature and systemic arterioles; the toxicity site is the cerebral vasculature
Kind of result
The kind of result is not recorded
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
Its recorded molecular formula is C9H13NO, weighing 151.21.
PubChem record · 10297 · read 2026-08-29
Where each sentence above came from
A person wrote this explanation into the record, with the studies named in the path below.
A reviewer approved this sentence against this exact record and its sources.
The limit a reviewer approved as the one that matters most here.
The four opening statements run to 83 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.
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.
Formulation
A formulation is the exact made-up form a substance comes in.
A picture of it, and where the picture fails
It is like the difference between a whole bean and instant coffee.
Where that stops being true. Coffee tastes different. A formulation can change how much reaches the blood.
What people get wrong. Two products with the same name are assumed to behave the same. They often do not.
The specific composition and physical form of a product, including salt, excipients and release profile.
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.
Association between phenylpropanolamine-containing products and subarachnoid or intracerebral haemorrhage in adults aged 18 to 49
✓ The study showed what it set out to show
Who was studied
Hemorrhagic Stroke Project (Kernan et al.)
How many people
2078
Study design
Multicentre case-control study, 43 United States hospitals, 1994-1999
Compared against
Not recorded for this study
Kind of result
A number that stands in for health
What was found
Women, appetite suppressants: adjusted odds ratio 16.58 (95% CI 1.51 to 182.21), P = 0.02; women, first use of any PPA product: 3.13 (0.86 to 11.46), P = 0.08; combined, cough and cold remedies: 1.23 (0.68 to 2.24), P = 0.49
Repeated elsewhere
Unreplicated
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 appetite-suppressant confidence interval spans two orders of magnitude on a small number of exposed cases. No men reported appetite suppressant use, and men showed no increased risk with cough and cold remedies.
How far it carries. This study is recorded from the curated record, not from the registry match.
Form and route. Oral tablet, capsule or syrup, sold over the counter
Interval reported. 95% CI 1
Written into the record, not signed off as a reviewed claim.
21 CFR 216.24 — Drug products withdrawn or removed from the market for reasons of safety or effectiveness (entry: phenylpropanolamine) (https://www.ecfr.gov/… · a recorded source, not a stored snapshot
Independent risk factors for aneurysmal subarachnoid haemorrhage in adults aged 18 to 49
✓ The study showed what it set out to show
Who was studied
Hemorrhagic Stroke Project, aneurysmal subarachnoid haemorrhage analysis (Broderick et al.)
How many people
930
Study design
Case-control analysis within the same cohort, 44 hospitals
Compared against
Not recorded for this study
Kind of result
A number that stands in for health
What was found
Current smoking adjusted odds ratio 3.73 (95% CI 2.67 to 5.21); hypertension 2.21 (1.48 to 3.29); caffeine in pharmaceutical products 2.48 (1.19 to 5.20); cocaine within 3 days bivariate exact odds ratio 24.97
Repeated elsewhere
Partially 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. Several over-the-counter stimulant exposures are associated with the same outcome in the same population, which is the confounding structure any single-exposure estimate has to survive.
How far it carries. This study is recorded from the curated record, not from the registry match.
Form and route. Oral tablet, capsule or syrup, sold over the counter
Interval reported. 95% CI 2
Written into the record, not signed off as a reviewed claim.
21 CFR 216.24 — Drug products withdrawn or removed from the market for reasons of safety or effectiveness (entry: phenylpropanolamine) (https://www.ecfr.gov/… · 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
Phenylpropanolamine
What a person takes: Oral tablet, capsule or syrup, sold over the counter.
The measurement behind this step
Immediate-release or polistirex extended-release oral phenylpropanolamine, alone in appetite suppressants and combined with antihistamines and antitussives in cold preparations. Well absorbed, largely excreted unchanged in urine.
Getting in
An over-the-counter tablet, capsule or syrup
Bought without a prescription in a supermarket or pharmacy, as a cold remedy or a diet pill.
╌╌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 phenylpropanolamine hydrochloride, immediate-release or as a polistirex resin complex for extended release, usually combined with an antihistamine or antitussive in cold preparations and given alone in appetite suppressants.
It is absorbed well from the gut and travels everywhere, not just to the nose.
╌╌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
Well absorbed orally with limited metabolism and substantial renal excretion of unchanged drug. Crosses into the central nervous system, which is the basis of the appetite-suppressant effect.
It switches on the receptors that tighten blood vessels, and separately pushes the body's own adrenaline-like signal out of nerve endings.
──Measured in people. Written by a person from the study named beside the step. Not signed off as a reviewed claim.
The measurement behind this step
Direct alpha-1 adrenergic receptor agonism combined with indirect displacement of noradrenaline from sympathetic nerve terminals. The indirect component means the effect depends on the patient's own sympathetic stores and is not straightforwardly dose-proportional.
Vasoconstriction in the nose — and everywhere else
Nasal tissue shrinks and the airway opens. Every other small artery narrows too, and blood pressure rises.
╌╌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
Alpha-1-mediated contraction of nasal mucosal vasculature reduces mucosal blood volume and relieves congestion. Systemic arteriolar constriction raises peripheral resistance and blood pressure, with cerebral vessels exposed to the same pressor effect.
Congestion relieved; a haemorrhagic stroke signal in young women
Blocked noses cleared and appetite fell slightly. In a study of young stroke patients, diet-pill use in women was strongly associated with brain haemorrhage.
──Measured in people. Written by a person from the study named beside the step. Not signed off as a reviewed claim.
The measurement behind this step
Measured: adjusted odds ratio 16.58 (95% CI 1.51 to 182.21) for appetite suppressants in women, 3.13 (0.86 to 11.46) for first use of any phenylpropanolamine product, 1.23 (0.68 to 2.24) for cough and cold remedies combined across sexes.
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.
Nobody, in human medicine in the United States. Phenylpropanolamine appears in 21 CFR 216.24 as a drug product withdrawn for reasons of safety or effectiveness. It remains in veterinary use for urinary sphincter incompetence in dogs.
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.
Where the result stopped carrying
On open sale for roughly a quarter of a century while case reports of first-dose haemorrhagic stroke accumulated
Removed by FDA public health advisory in November 2000 and voluntary reformulation, not by a prohibition order
Codified in 21 CFR 216.24 as "all drug products containing phenylpropanolamine"
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.
A different form was studied
The studied form is not the form on the shelf.
On this record: This record is linked to 1 related forms. Evidence does not carry across all of them.
Something else had to happen too
In the studies it was paired with training, a diet or another treatment.
On this record: Bought without a prescription in a supermarket or pharmacy, as a cold remedy or a diet pill.
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 (9)
It was studied for a different goal
The studies measured something else entirely. 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.
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
Withdrawn
❝ 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, capsule or syrup, sold over the counter
✎ 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: S8.
No source is stored against this line.
What is in the pack
Immediate-release or polistirex extended-release oral phenylpropanolamine, alone in appetite suppressants and combined with antihistamines and antitussives in cold preparations. Well absorbed, largely excreted unchanged in urine.
✎ 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
Removed from the United States market from November 2000 and listed in 21 CFR 216.24. The decisive finding is an adjusted odds ratio of 16.58 (95% CI 1.51 to 182.21) for haemorrhagic stroke with appetite-suppressant use in women aged 18 to 49; the estimates for cough and cold products did not reach significance. Expected sympathomimetic effects include hypertension, tachycardia, palpitations, insomnia, restlessness and headache, and blood pressure elevation is the proposed mechanism of the stroke association. Interaction with monoamine oxidase inhibitors is the classic severe pressor interaction for this class.
Nobody counted how many people took this and were fine, so this cannot be turned into a rate.
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, capsule or syrup, sold over the counter
✎ 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
Well absorbed, largely excreted unchanged in urine.
✎ 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
4 products list this as an active ingredient in the United States drug directory. 4 of them contain it and nothing else.
FDA National Drug Code directory · 58747-7275 · read 2026-08-29
They are sold as powder.
FDA National Drug Code directory · 58747-7275 · read 2026-08-29
101 marketed supplement labels list this ingredient, classed as botanical and 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.
Evidence on this page does not automatically apply to this one.
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, withdrawn medicine. The questions below are for a clinician or pharmacist.
Questions worth asking
Which of the trials of Phenylpropanolamine 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 the risk in women is approximately sixteenfold — the data are equally compatible with 1.5 and with 182
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 cough and cold products carried demonstrated stroke risk; those estimates did not reach significance
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 estimate is clean of confounding by other over-the-counter stimulants, which the same cohort separately associated with the same outcome
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.
How much did people take in the studies?
The sources RNAWiki checked hold nothing for this field.
Why it matters. A result belongs to an amount. Without the amount the result floats free.
What would answer it
A stored source that records 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 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 Phenylpropanolamine 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.
Adjusted odds ratio 16.58 for appetite suppressants in women — interval 1.51 to 182.21
In plain words
A case-control study of 702 stroke patients found women who had taken a phenylpropanolamine diet pill were far more likely to have had a brain haemorrhage. The estimate is very uncertain.
What was measured
Adjusted odds ratio for haemorrhagic stroke by phenylpropanolamine product type and sex
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
The Hemorrhagic Stroke Project recruited men and women aged 18 to 49 from 43 United States hospitals, requiring a subarachnoid or intracerebral haemorrhage within 30 days of enrolment and no previously diagnosed brain lesion, with two random-digit-dialled matched controls per patient: 702 patients and 1,376 controls. In women, the adjusted odds ratio for appetite suppressants containing phenylpropanolamine was 16.58 (95% CI 1.51 to 182.21, P = 0.02), and for first use of any phenylpropanolamine-containing product 3.13 (95% CI 0.86 to 11.46, P = 0.08). All first uses involved cough or cold remedies. For men and women combined the odds ratio for any phenylpropanolamine product was 1.49 (95% CI 0.84 to 2.64, P = 0.17), for cough and cold remedies 1.23 (95% CI 0.68 to 2.24, P = 0.49), and for appetite suppressants 15.92 (95% CI 1.38 to 184.13, P = 0.03). No men reported appetite suppressant use.
Written into the record, not signed off as a reviewed claim
The interval spans two orders of magnitude, and the point estimate is what was quoted
In plain words
An odds ratio of 16.58 sounds precise. The range of values compatible with the data runs from 1.5 to 182, which is a very different statement.
What was measured
That phenylpropanolamine multiplies haemorrhagic stroke risk approximately sixteenfold in women
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
The appetite-suppressant estimate in women rests on a small number of exposed cases, which is why the 95 per cent confidence interval runs from 1.51 to 182.21. The lower bound excludes 1, so the association is statistically significant; the width means the data are compatible with a risk increase of 50 per cent and with one of eighteen thousand per cent. Reporting the point estimate as "sixteen times the risk" states one value from that range as though the study had resolved it. The cough and cold estimate, which covered by far the larger exposed population, did not reach significance in women (P = 0.08) or in the combined analysis (P = 0.49), and men showed no increased risk with cough and cold remedies at all.
Written into the record, not signed off as a reviewed claim
The whole category went, not just the diet pills
In plain words
The strong finding was for diet pills. The cough and cold products, where the evidence was much weaker, were removed too.
What was measured
Not recorded
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
The two exposures behaved differently in the data. Appetite suppressants: adjusted odds ratio 16.58 in women, P = 0.02, significant. Cough and cold remedies: 1.23 combined, P = 0.49, not significant, and no increased risk in men. The regulatory response covered both, on the reasoning that all first uses associated with stroke involved cough or cold products, that the first-use estimate in women was 3.13 with P = 0.08, and that the benefit of an over-the-counter decongestant is small enough that even a poorly resolved risk outweighs it. That reasoning is defensible and it is a benefit-risk judgement rather than a finding. The evidentiary basis for removing the decongestants is materially weaker than the basis for removing the appetite suppressants, and the record should say so.
Written into the record, not signed off as a reviewed claim
The same study group also implicated other over-the-counter sympathomimetics
In plain words
The same investigators went on to look at ephedra products and at pharmaceutical caffeine and nicotine, and found associations there too.
What was measured
Adjusted odds ratios for aneurysmal subarachnoid haemorrhage by modifiable risk factor in the same case-control cohort
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
The Hemorrhagic Stroke Project team published further analyses from the same case-control infrastructure: an association between ephedra-containing products and haemorrhagic stroke, and, in the subarachnoid haemorrhage subset of 312 aneurysmal cases and 618 matched controls, independent associations with current smoking (adjusted odds ratio 3.73, 95% CI 2.67 to 5.21), hypertension (2.21, 1.48 to 3.29), cocaine use within three days (bivariate exact odds ratio 24.97), and caffeine in pharmaceutical products (2.48, 95% CI 1.19 to 5.20). This matters for interpreting the phenylpropanolamine result: the exposure sits inside a cluster of correlated over-the-counter stimulant exposures in a young population, and the adjustment model has to separate them.
Written into the record, not signed off as a reviewed claim
A whole class of products vanished on an advisory, without a formal ban
In plain words
The FDA issued a public health advisory in November 2000 and asked manufacturers to reformulate. The products disappeared without a prohibition order.
What was measured
Not recorded
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
Phenylpropanolamine was not a single-sponsor prescription drug with an application to withdraw. It was an over-the-counter ingredient in hundreds of products from dozens of manufacturers. The FDA issued a public health advisory in November 2000 and requested voluntary reformulation, and the ingredient left the market within months. The formal codification followed: phenylpropanolamine now appears in 21 CFR 216.24 as "all drug products containing phenylpropanolamine". This is a different mechanism from every prescription withdrawal in this file — market removal by advisory rather than by order — and it is what makes an over-the-counter safety signal act faster than a prescription one, not slower.
Source
21 CFR 216.24, current as of August 2026
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
It is still a medicine, for dogs
In plain words
Phenylpropanolamine remains a standard veterinary treatment for urinary incontinence in dogs, where the same vessel-and-sphincter tightening is exactly what is wanted.
What was measured
Not recorded
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
Phenylpropanolamine is used in veterinary medicine for urethral sphincter mechanism incompetence in dogs, where alpha-adrenergic tone at the internal urethral sphincter is the therapeutic target. The 21 CFR 216.24 listing addresses human drug products. As with pergolide elsewhere in this file, the same molecule is unacceptable in one species and standard in another, because the alternatives, the life expectancy and the baseline stroke risk are all different. A withdrawal is a judgement about a specific benefit-risk trade in a specific population.
Source
21 CFR 216.24 — human drug products containing phenylpropanolamine
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
Twenty-four years on the shelf, and the study that ended it was commissioned by industry
In plain words
Case reports linking the drug to brain haemorrhage had accumulated for years. The definitive study was funded by the manufacturers themselves and took five years to run.
What was measured
Not recorded
Effect estimate
No reviewed effect estimate exists for this record.
Limits
This entry records a failure.
From the source
Case reports linking phenylpropanolamine-containing products to haemorrhagic stroke, often after a first dose, had accumulated well before the Hemorrhagic Stroke Project was designed. The project enrolled between 1994 and 1999 across 43 hospitals and published in December 2000, and the FDA advisory followed within weeks of publication. The interval between a recognised signal and a resolving study is the recurring pattern in this file: the signal is cheap and ambiguous, the study is expensive and slow, and the product stays on sale throughout. Here the product was on open supermarket shelves for that entire period.
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What is not here
7 questions this page could not answer
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What was measured, goal by goal — found nothing in the sources checked.
How close this is to real life — found nothing in the sources checked.
Felt, measured, or meaningful — found nothing in the sources checked.
How long anything takes — found nothing in the sources checked.
What it may clash with — found nothing in the sources checked.
Other ways to the same goal — found nothing in the sources checked.
What changed on this page — found nothing in the sources checked.
The record as stored
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The older medicine-wide conclusion held in this record
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An over-the-counter sympathomimetic removed from the United States market in 2000 on a single case-control study of 702 haemorrhagic stroke patients and 1,376 controls, which found an adjusted odds ratio of 16.58 for appetite-suppressant use in women — a figure whose 95 per cent confidence interval runs from 1.51 to 182.21.
Recorded evidence blocks (1)
Q3
Where do the label and the trials disagree about Phenylpropanolamine?
"withdrawn" against "approved": withdrawal status vs register status for Phenylpropanolamine.
✗ required summary fields resolved: 4 required field(s) not terminal: Why people use it, Best-supported result, Biggest unanswered question, Human evidence
✓ public claims reviewed: 0 reviewed claim(s); drafts are never rendered
✓ source coverage passed: 3 source rows
✓ no critical contamination: no quarantine open
✓ canonical metadata passed: slug and display name present
✓ no raw internal fields: enforced by the copy-contract test over the rendered page
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