The use the label states, quoted from it. No plain-language version of this sentence has been written.
The use the label states, quoted from it. It is written for a clinician, not for a reader without medical training.
No statement of the main limit is recorded.
The four opening statements run to 23 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.
Biomarker
A biomarker is a number from a test that stands in for something about health.
A picture of it, and where the picture fails
A biomarker is like a fuel gauge.
Where that stops being true. A gauge is wired to the tank. Many biomarkers are only loosely tied to health.
What people get wrong. A better number is read as a better life. Several medicines improved a number and helped nobody.
A measurable indicator used as a substitute for a clinical outcome of interest.
Placebo
A placebo is a dummy treatment given so the real one can be compared with it.
A picture of it, and where the picture fails
A placebo is like a blank control in an experiment.
Where that stops being true. A blank does nothing. People given a placebo often do get better.
What people get wrong. A placebo effect is read as imaginary. The improvement is measured and real.
An inactive intervention matched in appearance to the test intervention, used to control for non-specific effects.
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.
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 among children 1-36 months of age
✗ The study did not show it
Who was studied
NCT00109551
How many people
58000
Study design
Phase 3
Compared against
Not recorded for this study
Kind of result
Living longer, or avoiding a major event
What was found
Result not recorded on this page
Repeated elsewhere
Unreplicated
What this does not prove. A study that did not show an effect does not show that no effect exists anywhere.
The limits of this study, and where it came from
Main limit. No limitation is recorded for this study.
How far it carries. This study is recorded from the curated record, not from the registry match.
Form and route.
Interval reported. Not recorded in this summary
Written into the record, not signed off as a reviewed claim.
openFDA Drugs@FDA · a recorded source, not a stored snapshot
openFDA NDC Directory · a recorded source, not a stored snapshot
Europe PMC · a recorded source, not a stored snapshot
ClinicalTrials.gov · a recorded source, not a stored snapshot
Work and Iron Status Evaluation
✗ The study did not show it
Who was studied
NCT00094042
How many people
16000
Study design
Not applicable
Compared against
Not recorded for this study
Kind of result
A number that stands in for health
What was found
Result not recorded on this page
Repeated elsewhere
Unreplicated
What this does not prove. A study that did not show an effect does not show that no effect exists anywhere.
The limits of this study, and where it came from
Main limit. No limitation is recorded for this study.
How far it carries. This study is recorded from the curated record, not from the registry match.
Form and route.
Interval reported. Not recorded in this summary
Written into the record, not signed off as a reviewed claim.
openFDA Drugs@FDA · a recorded source, not a stored snapshot
openFDA NDC Directory · a recorded source, not a stored snapshot
Europe PMC · a recorded source, not a stored snapshot
ClinicalTrials.gov · a recorded source, not a stored snapshot
Changes in mean hemoglobin concentrations
✗ The study did not show it
Who was studied
NCT02567981
How many people
4577
Study design
Not applicable
Compared against
Not recorded for this study
Kind of result
A number that stands in for health
What was found
Result not recorded on this page
Repeated elsewhere
Unreplicated
What this does not prove. A study that did not show an effect does not show that no effect exists anywhere.
The limits of this study, and where it came from
Main limit. No limitation is recorded for this study.
How far it carries. This study is recorded from the curated record, not from the registry match.
Form and route.
Interval reported. Not recorded in this summary
Written into the record, not signed off as a reviewed claim.
openFDA Drugs@FDA · a recorded source, not a stored snapshot
openFDA NDC Directory · a recorded source, not a stored snapshot
Europe PMC · a recorded source, not a stored snapshot
ClinicalTrials.gov · a recorded source, not a stored snapshot
Return to non-anemic status in the last trimester of pregnancy
✗ The study did not show it
Who was studied
NCT05358509
How many people
4368
Study design
Phase 4
Compared against
Not recorded for this study
Kind of result
A number that stands in for health
What was found
Result not recorded on this page
Repeated elsewhere
Unreplicated
What this does not prove. A study that did not show an effect does not show that no effect exists anywhere.
The limits of this study, and where it came from
Main limit. No limitation is recorded for this study.
How far it carries. This study is recorded from the curated record, not from the registry match.
Form and route.
Interval reported. Not recorded in this summary
Written into the record, not signed off as a reviewed claim.
openFDA Drugs@FDA · a recorded source, not a stored snapshot
openFDA NDC Directory · a recorded source, not a stored snapshot
Europe PMC · a recorded source, not a stored snapshot
ClinicalTrials.gov · a recorded source, not a stored snapshot
Preterm delivery
✗ The study did not show it
Who was studied
NCT00488579
How many people
4326
Study design
Phase 4
Compared against
Not recorded for this study
Kind of result
A number that stands in for health
What was found
Result not recorded on this page
Repeated elsewhere
Unreplicated
What this does not prove. A study that did not show an effect does not show that no effect exists anywhere.
The limits of this study, and where it came from
Main limit. No limitation is recorded for this study.
How far it carries. This study is recorded from the curated record, not from the registry match.
Form and route.
Interval reported. Not recorded in this summary
Written into the record, not signed off as a reviewed claim.
openFDA Drugs@FDA · a recorded source, not a stored snapshot
openFDA NDC Directory · a recorded source, not a stored snapshot
Europe PMC · a recorded source, not a stored snapshot
ClinicalTrials.gov · a recorded source, not a stored snapshot
incidence of clinical malaria (if fever recorded a blood sample will be taken to determine parasite species and count)
✗ The study did not show it
Who was studied
NCT01001871
How many people
3880
Study design
Not applicable
Compared against
Not recorded for this study
Kind of result
A number that stands in for health
What was found
Result not recorded on this page
Repeated elsewhere
Unreplicated
What this does not prove. A study that did not show an effect does not show that no effect exists anywhere.
The limits of this study, and where it came from
Main limit. No limitation is recorded for this study.
How far it carries. This study is recorded from the curated record, not from the registry match.
Form and route.
Interval reported. Not recorded in this summary
Written into the record, not signed off as a reviewed claim.
openFDA Drugs@FDA · a recorded source, not a stored snapshot
openFDA NDC Directory · a recorded source, not a stored snapshot
Europe PMC · a recorded source, not a stored snapshot
ClinicalTrials.gov · a recorded source, not a stored snapshot
What we know
RNAWiki holds 6 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 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
No description of who was studied is recorded.
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
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
Prescription only
❝ 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
Not recorded.
∅ Nothing recorded
Where this came from
RNAWiki holds nothing here and says so rather than guessing.
No form or route is recorded.
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
Not recorded.
∅ Nothing recorded
Where this came from
RNAWiki holds nothing here and says so rather than guessing.
Nothing is recorded about product quality.
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∅Nothing found in the sources checked
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.
∅Nothing found in the sources checked
No harm is recorded against this substance in the sources RNAWiki checked. Finding nothing is not the same as showing there is nothing.
The sources listed were searched and held nothing. That is not the same as nothing existing.
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
Not recorded.
∅ Nothing recorded
Where this came from
RNAWiki holds nothing here and says so rather than guessing.
The exact form studied is not recorded.
No source is stored against this line.
What is sold
Not recorded.
∅ Nothing recorded
Where this came from
RNAWiki holds nothing here and says so rather than guessing.
Nothing further is recorded about which forms are sold.
No source is stored against this line.
What is recorded as being sold
66 published labels name it as an active ingredient. 7 of them describe this substance alone, which is where its own label text on this page comes from.
US prescribing information · 597caf33-5107-9dec-e063-6294a90a5fcd · read 2026-08-29
Those labels are classed as human otc drug and human prescription drug.
US prescribing information · 597caf33-5107-9dec-e063-6294a90a5fcd · read 2026-08-29
3437 marketed supplement labels list this ingredient, classed as mineral.
Those labels carry all other and nutrient 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.
This order is fixed in code and does not count clicks or time on the page.
What is not here
9 questions this page could not answer
These sections were prepared and left out because there was nothing to put in them. They are listed rather than hidden, so the gaps in this record are visible.
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.
The path through the body — 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.
Claims that go past the evidence — found nothing in the sources checked.
What changed on this page — found nothing in the sources checked.
The record as stored
The full record, for auditing
Everything above is built from what is below. This layer keeps the technical vocabulary, record identifiers and every stored row, so a reader who wants to check the page can.
Recorded evidence blocks (6)
Q2
245 registered trials of Ferrous Sulfate — at which phases?
Registered studies posting no result
196 of 245
245 registered studies of Ferrous Sulfate: 91 na, 60 phase4, 55 phase3, 27 phase2, 7 na or unstated, 7 phase1, 5 early phase1. CLINICALTRIALS_SNAPSHOT · 2026-09-01
326 with a PubMed record
Show the evidence
na
91
phase4
60
phase3
55
phase2
27
na or unstated
7
phase1
7
8 more recorded rows
early phase1
5
completed
158
unknown
32
recruiting
16
terminated
16
not yet recruiting
12
withdrawn
10
enrolling by invitation
1
recorded 2026-09-01 · last checked 2026-09-04
Q3
25 of Ferrous Sulfate's trials stopped: safety, accrual/recruitment, funding/business, other?
safety (2), accrual/recruitment (9), funding/business (5) and other (9): Ferrous Sulfate's stop wording, clustered. CLINICALTRIALS_SNAPSHOT · 2026-09-01
"The study was terminated because of significant enrollment challenges"; 25 of 245 registered studies
Show the evidence
Trial
NCT00223938
terminated; "The study was terminated because of significant enrollment challenges"
NCT00459225
withdrawn; "Difficulty recruiting subjects"
NCT00497471
terminated; "Follow-up end in 1999"
NCT00830037
terminated; "Terminated by the DSMB based on low chance of finding differences in mGFR slopes, but higher risk of serious adverse events in the IV iron group (aIRR = 1.60)"
NCT00929409
terminated; "Stopped prematurely because too few patients were recruited."
NCT00999479
withdrawn; "Poor enrollment"
14 further recorded trials
NCT01155375
terminated; "Several factors contributed to significant challenges in enrollment and led the Sponsor to discontinue the AMAG-FER-CKD-251 study as designed."
NCT01155388
terminated; "Several factors contributed to significant challenges in enrollment and led the Sponsor to discontinue the AMAG-FER-CKD-252 study as designed."
NCT01438372
withdrawn; "The study was terminated prior to enrolling patients as we were unable to secure enough funding to complete the study."
NCT01656434
terminated; "Business reasons"
NCT01837030
withdrawn; "not feasible due to funding"
NCT01865175
withdrawn; "Institution required IND, although FDA did not, so institution did not allow enrollment"
NCT01908543
terminated; "Technical issues with availability of relevant personnel"
NCT01975272
terminated; "Disapointing randomization rate"
NCT02564796
terminated; "COVID"
NCT02825719
terminated; "Ulipristal was withdrawal from the market"
NCT02839096
terminated; "Lack of funds, PI left University"
NCT03777514
withdrawn; "Study wasn't started."
NCT03944733
withdrawn; "The study was never started as a result of change of personnel and funding"
NCT04087993
withdrawn; "difficult recruitment - redesign in discussion"
recorded 2026-09-01 · last checked 2026-09-04
Q4
Human studies of Ferrous Sulfate used iron (2 mg/kg/daily) — over how long?
studies of Ferrous Sulfate used the recorded amount. ClinicalTrials.gov · 2026-09-01
20 recorded entries; human; oral; also "iron (2 mg/kg/daily)", "Upsher-Smith ferrous sulfate 325 mg tablets NDC# 00245-0108-11", "Ferrous sulfate 325mg"
Which 108 trials of Ferrous Sulfate posted no result?
Posted no result
108 of 108 completed trials
Registrations
NCT00998998, NCT04363905, NCT00284700, NCT02346188, NCT00236964 and NCT00822380, and 102 more
Completion dates
oldest 1996-07; newest 2024-08-31
Show the evidence
Trial
NCT00998998
1996-07
NCT04363905
2000-12-31
NCT00284700
2001-05
NCT02346188
2001-12
NCT00236964
2002-05-30
NCT00822380
2004-11
14 further recorded trials
NCT02146053
2004-12
NCT00701246
2006-03
NCT00276224
2006-04
NCT00301054
2006-04
NCT00841061
2006-05
NCT00953134
2008-03
NCT00867867
2008-06
NCT00374790
2008-07
NCT00364104
2008-12
NCT01078818
2009-05
NCT00919230
2009-08
NCT01383798
2009-12
NCT01047098
2010-04
NCT01991600
2010-05
Q6
At the median, Ferrous Sulfate's trials enrolled 90 people — anything larger?
Median enrolment
90
Largest enrolment
406902
Registered trials counted
244
Q7
What do 758 spontaneous reports say about Ferrous Sulfate — 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.
Ferrous Sulfate appears in spontaneous reports to regulators. Across the 10 most-reported reaction terms, 758 reaction mentions were counted: drug hypersensitivity 115; premature baby 91; acute kidney injury 81; constipation 80. FAERS via Open Targets · CHEMBL1200830 · 2026-06-24
Show the evidence
drug hypersensitivity
115
premature baby
91
acute kidney injury
81
constipation
80
premature delivery
79
anaemia
76
4 more recorded rows
abdominal pain
76
low birth weight baby
68
drug intolerance
53
asthma
39
recorded 2026-06-24 · last checked 2026-09-04
Where it is registeredIdentifiers, relations and other names
ChEMBL 37 — CC BY-SA 3.0 Unported · ChEMBL ATC CC BY-SA · ClinicalTrials.gov — US Government work · Open Targets 26.06 — CC0 · mixed register set; per-register licences in docs/specs/corpus-20k-sources.md
✗ required summary fields resolved: 3 required field(s) not terminal: Best-supported result, Biggest unanswered question, Human evidence
✓ public claims reviewed: 0 reviewed claim(s); drafts are never rendered
✓ source coverage passed: 5 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
This is a record of evidence. It is not medical advice, and it does not say this substance suits you. Nothing here says any substance on RNAWiki is appropriate for a child.