This page shows what was measured, who it was measured in, and what that does not settle.
What Cromoglicic acid does in the body
Most allergy drugs block the receiver of the histamine signal.
This one was designed to stop the signal being sent: to make the cells that store histamine less willing to release it when they meet an allergen. Because it barely gets absorbed, it only works on whatever surface you apply it to — the nose, the eye, the airway lining — and it has to be there before the allergen arrives. Exactly how it calms those cells has never been settled.
Why people take it. Preventing asthma attacks, hay fever and itchy eyes before they start — and, by mouth, the gut symptoms of mastocytosis
What happened in people
No statistically significant difference from placebo on percentage of symptom-free days across four pooled paediatric asthma trials
✎ 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.
Only six products remain in the CMS acquisition survey, the smallest count of any drug in this batch, at $0.5845 per millilitre
Where it acts
The mucosal surface it is applied to — bronchial epithelium, nasal mucosa, conjunctiva, or gut lumen. Almost none of it is absorbed, which is the whole design
Kind of result
Symptoms and quality of life
Supervision
RNAWiki has not recorded a supervision or regulatory status for this substance.
What the registries record it as
The substance registry classes this as chemical.
FDA substance registry · Y0TK0FS77W · read 2026-08-29
Its recorded molecular formula is C23H14Na2O11, weighing 512.34.
US prescribing information · 00623958-a8fe-47d1-a0d2-0aa4e2f7966e · read 2026-08-30
Where each sentence above came from
A person wrote this explanation into the record, with the studies named in the path below.
The recorded use, written for a reader without medical training. Not signed off.
A limit recorded against this substance. Not signed off as a reviewed claim.
The four opening statements run to 115 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.
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.
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.
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.
Efficacy of sodium cromoglycate against placebo as maintenance therapy in children aged 0 to 18
✗ The study did not show it
Who was studied
Cochrane CD002173.pub2 — inhaled sodium cromoglycate for asthma in children
How many people
1026
Study design
Systematic review and meta-analysis of 23 double-blind placebo-controlled trials
Compared against
A dummy treatment
Kind of result
A number that stands in for health
What was found
No statistically significant difference on percentage of symptom-free days; other symptom outcomes significant with small effects; funnel plot indicating publication bias
Repeated elsewhere
Failed to Replicate
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. Trials published 1970 to 1997, mostly crossover, few reporting allocation concealment. The authors state publication bias is likely to have overestimated the beneficial effects.
How far it carries. This study is recorded from the curated record, not from the registry match.
Form and route. Four route-specific formulations: inhalation solution for nebulisation, nasal solution over the counter, ophthalmic solution, and oral concentrate
Interval reported. Not recorded in this summary
Written into the record, not signed off as a reviewed claim.
Drugs@FDA: GASTROCROM (cromolyn sodium) oral concentrate, NDA 020479, approved 29 February 1996; generic cromolyn sodium for inhalation (ANDA 075271, 2000), … · a recorded source, not a stored snapshot
Participant-reported severity of ocular itching, irritation, tearing and photophobia
✓ The study showed what it set out to show
Who was studied
Cochrane CD009566.pub2 — topical antihistamines and mast cell stabilisers
How many people
4344
Study design
Systematic review of 30 randomised trials across 17 drugs or comparisons
Compared against
Not recorded for this study
Kind of result
A number that stands in for health
What was found
All reported agents, cromoglicate among them, reduced symptoms and signs against placebo in the short term; no serious adverse events reported for the class
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. Treatment periods of one to eight weeks only, with no long-term efficacy data for any drug in the class. Meta-analysis was possible for one comparison, which did not involve cromoglicate.
How far it carries. This study is recorded from the curated record, not from the registry match.
Form and route. Four route-specific formulations: inhalation solution for nebulisation, nasal solution over the counter, ophthalmic solution, and oral concentrate
Interval reported. Not recorded in this summary
Written into the record, not signed off as a reviewed claim.
Drugs@FDA: GASTROCROM (cromolyn sodium) oral concentrate, NDA 020479, approved 29 February 1996; generic cromolyn sodium for inhalation (ANDA 075271, 2000), … · 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
Cromoglicic acid
What a person takes: Four route-specific formulations: inhalation solution for nebulisation, nasal solution over the counter, ophthalmic solution, and oral concentrate.
The measurement behind this step
Each formulation treats only the surface it reaches, because the molecule is not absorbed. All require dosing several times daily to maintain local concentration, since there is no plasma half-life doing that work. The inhalation label describes it as a prophylactic given on a regular daily basis, with effect usually evident after several weeks though some patients respond almost immediately.
Getting in
Applied to a surface, and it stays there
Sprayed into the nose, nebulised into the lungs, dropped into the eye, or swallowed to reach the gut lining. Which formulation you use decides which surface is treated, because none of it travels.
╌╌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
Two carboxylic acids fully ionised at physiological pH give a doubly anionic molecule with negligible absorption across any epithelium. Four separate route-specific formulations exist for that reason, and the oral concentrate acts on gut mucosal mast cells without entering the circulation.
The molecule is far too charged to cross a cell membrane. Whatever it does, it does from the outside — which is one reason the mechanism has been so hard to pin down.
╌╌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 double negative charge that prevents systemic absorption equally prevents passive entry into mast cells. Any mechanism must therefore operate at the cell surface or through a surface receptor, which is what makes the GPR35 hypothesis structurally attractive and the classical membrane-stabilisation account structurally awkward.
The classical account: the mast cell is stabilised
The traditional explanation is that it makes the mast cell membrane less likely to open and release its contents when an allergen arrives. This is the phrase the whole drug category is named after.
╌╌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
Early studies attributed the cromones’ prevention of allergic reactions to mast cell stabilising properties. The 2017 review states the exact pharmacological mechanism remained a mystery, and that the account cannot explain the discrepancies between species and between mast cell subtypes in their response to the drugs.
One idea is that the drug activates a specific receptor on the cell surface. The other is that it boosts one of the body’s own anti-inflammatory systems, the one steroids also use. Both have evidence and neither has closed the question.
╌╌Measured in animals. A result in animals says what to test next. It does not say what happens in people.
The measurement behind this step
Cromoglycate, nedocromil and zaprinast increase inositol phosphate accumulation and calcium mobilisation in HEK cells transfected with the orphan receptor GPR35, though its relevance to mast cell mediator release is unelucidated. Separately, cromones potentiate glucocorticoid-induced annexin A1 release by inhibiting PP2A phosphatase, and annexin A1 depletion in vitro completely reverses their inhibitory actions.
The allergic reaction is smaller, if it is prevented in advance
Used regularly and started before exposure, less histamine is released and the reaction is milder. Used during a reaction it does nothing, because it works upstream of everything that is already happening.
──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
The inhalation label describes it as a prophylactic agent given on a regular daily basis, with effect usually evident after several weeks though some patients respond almost immediately. There is no receptor-blocking component, so nothing in the mechanism addresses mediators already released.
On the cleanest measure in childhood asthma — days with no symptoms — pooling the trials found no difference from placebo, and the shape of the published literature suggested negative studies were missing.
╌╌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
Twenty-three trials in 1,026 children published 1970 to 1997; percentage of symptom-free days showed no statistically significant difference; other symptom outcomes reached significance with small effects and wide intervals; funnel plot indicated under-representation of small negative studies.
No suggested links are held for this record, so nothing is hidden from this path.
What we know
The record describes 6 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.
Historically children with asthma, and still people with allergic rhinitis and allergic conjunctivitis over the counter. The oral concentrate is used for mastocytosis, where the target cell is unambiguously the mast cell.
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 pediatric, the label states: “In adult rats no adverse effects of cromolyn sodium were observed at oral doses up to 6144 mg/kg (approximately 25 times the maximum recommended daily oral dose in adults on a mg/m 2 basis).”
US prescribing information · 00623958-a8fe-47d1-a0d2-0aa4e2f7966e · read 2026-08-30
On older people, the label states: “Clinical studies of GASTROCROM did not include sufficient numbers of subjects aged 65 and over to determine whether they respond differently from younger subjects.”
US prescribing information · 00623958-a8fe-47d1-a0d2-0aa4e2f7966e · read 2026-08-30
On people who are pregnant, the label states: “There are, however, no adequate and well controlled studies in pregnant women.”
US prescribing information · 00623958-a8fe-47d1-a0d2-0aa4e2f7966e · read 2026-08-30
On people who are breastfeeding, the label states: “It is not known whether this drug is excreted in human milk.”
US prescribing information · 00623958-a8fe-47d1-a0d2-0aa4e2f7966e · read 2026-08-30
Where the result stopped carrying
The pooled percentage of symptom-free days in childhood asthma showed no significant difference from placebo
Publication bias was detected in the paediatric asthma literature, with small negative studies under-represented
The drug lost its place as maintenance therapy for childhood asthma from 1990 onward as inhaled corticosteroids arrived
Every original brand — Intal, Opticrom, Crolom — has left the active Drugs@FDA product listing
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
Four route-specific formulations: inhalation solution for nebulisation, nasal solution over the counter, ophthalmic solution, and oral concentrate
✎ 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
RNAWiki has not recorded a supervision or regulatory status for this substance.
❝ Quoted from a source
Where this came from
Copied from a source RNAWiki stored, with the source named.
No register row and no identity class settled the question.
No source is stored against this line.
What is in the pack
Each formulation treats only the surface it reaches, because the molecule is not absorbed. All require dosing several times daily to maintain local concentration, since there is no plasma half-life doing that work. The inhalation label describes it as a prophylactic given on a regular daily basis, with effect usually evident after several weeks though some patients respond almost immediately.
✎ 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
Among the most benign safety profiles in this batch, and for a structural reason: a doubly anionic molecule that is essentially not absorbed cannot produce systemic toxicity. The Cochrane review of topical antihistamines and mast cell stabilisers reported no serious adverse events related to the class across 30 trials in 4,344 participants. Local irritation on application — throat irritation and cough with inhalation, nasal stinging and sneezing with the spray, transient burning with the drops — is the practical limit. The safety record is the strongest thing about this drug and it was never the reason it was displaced.
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
Four route-specific formulations: inhalation solution for nebulisation, nasal solution over the counter, ophthalmic solution, and oral concentrate
✎ 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
All require dosing several times daily to maintain local concentration, since there is no plasma half-life doing that work. The inhalation label describes it as a prophylactic given on a regular daily basis, with effect usually evident after several weeks though some patients respond almost immediately.
✎ 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
27 products list this as an active ingredient in the United States drug directory. 27 of them contain it and nothing else.
FDA National Drug Code directory · 42571-445 · read 2026-08-29
They are sold as liquid, powder, solution, solution, concentrate, solution/ drops and spray, metered, taken intrabronchial, nasal, ophthalmic and oral.
FDA National Drug Code directory · 42571-445 · read 2026-08-29
The regulator's established pharmacologic class for it is decreased histamine release [pe] and mast cell stabilizer [epc].
FDA National Drug Code directory · 42571-445 · read 2026-08-29
11 published labels name it as an active ingredient. 11 of them describe this substance alone, which is where its own label text on this page comes from.
US prescribing information · 93f80edb-3b38-423e-8cd6-5b5cb4393ec2 · read 2026-08-29
Those labels are classed as human otc drug and human prescription drug.
US prescribing information · 93f80edb-3b38-423e-8cd6-5b5cb4393ec2 · read 2026-08-29
Gastrocrom is oral at HOW SUPPLIED GASTROCROM Oral Concentrate is an unpreserved, colorless solution supplied in a low density polyethylene plastic unit dose ampule with 8 ampules per foil pouch., recorded as fda label in effect 2024-06-26 in the United States.
US prescribing information · 00623958-a8fe-47d1-a0d2-0aa4e2f7966e · read 2026-08-30
Recorded price in US: 0.33569–0.98098 USD per one millilitre, across 8 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.
RNAWiki could not confidently classify this substance, so no self-experiment plan is offered.
Questions worth asking
Which of the trials of Cromoglicic acid 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 "mast cell stabiliser" describes a known mechanism — the 2017 review calls the exact mechanism a mystery and notes species and subtype discrepancies the account cannot explain
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 statistically significant secondary symptom outcomes in childhood asthma reflect a real effect, given the publication bias the funnel plot indicates
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 GPR35 findings translate into therapeutic effect — the review states explicitly that it is unclear how they would
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 a mast-cell rationale established in mastocytosis transfers to asthma, where the pooled primary outcome was null
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 Cromoglicic acid 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.
Cochrane: no significant benefit on symptom-free days, and the missing studies were the negative ones
In plain words
Twenty-three trials in a thousand children were pooled. On the cleanest measure — how many days a child had no symptoms — the drug was no better than placebo. The pattern of published studies showed that small trials with negative results were missing from the literature.
What was measured
Percentage of symptom-free days, pooled across four trials, cromoglycate against placebo
Effect estimate
No reviewed effect estimate exists for this record.
Limits
This entry records a failure.
From the source
The Cochrane review searched for all double-blind placebo-controlled randomised trials of inhaled sodium cromoglycate as maintenance therapy in children aged 0 to 18 with asthma, screening 3,500 titles and including 24 papers reporting 23 studies published between 1970 and 1997, together enrolling 1,026 participants. Most were crossover studies and few provided enough information to judge allocation concealment. Four studies reported percentage of symptom-free days; pooling them revealed no statistically significant difference between cromoglycate and placebo. Other pooled symptom outcomes and bronchodilator use reached statistical significance but with small treatment effects, and the confidence intervals were wide enough that a clinically relevant effect could not be excluded either. The funnel plot showed an under-representation of small studies with negative results, indicating publication bias. The authors concluded there is insufficient evidence to be sure about efficacy over placebo, and that publication bias is likely to have overestimated the beneficial effects.
Written into the record, not signed off as a reviewed claim
The mechanism that named a whole drug class has never been established
In plain words
Cromolyn is the original "mast cell stabiliser" and the phrase was invented for it. Nearly sixty years after it was made, the pharmacologists reviewing it wrote that the exact mechanism remained a mystery.
What was measured
That cromolyn works by stabilising the mast cell membrane — the phrase that defines the class, offered without a confirmed molecular mechanism and contradicted by species and subtype discrepancies its own reviewers describe
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
A 2017 review by researchers including one of the original pharmacologists in the field states that while early studies attributed the cromones’ ability to prevent allergic reactions to their mast cell stabilising properties, the exact pharmacological mechanism by which this occurred remained a mystery, and that the classical account cannot explain the discrepancies between species and between mast cell subtypes in their response to these drugs. Two candidate mechanisms are advanced. First, the orphan G-protein coupled receptor GPR35: cromoglycate, nedocromil and zaprinast increase inositol phosphate accumulation and calcium mobilisation in HEK cells transfected with GPR35, though the review notes its significance to asthma, allergy or mast cell mediator release is yet to be elucidated and it is unclear how those actions would translate into therapeutic effect. Second, the annexin A1 and formyl peptide receptor anti-inflammatory loop: cromones potentiate glucocorticoid-induced annexin A1 release by inhibiting PP2A phosphatase activity, and depletion of annexin A1 in vitro completely reverses their inhibitory actions.
Written into the record, not signed off as a reviewed claim
It was displaced from asthma by a class with better evidence, not by a safety finding
In plain words
This drug was standard maintenance treatment for childhood asthma for years. Its use fell away from 1990 as inhaled steroids took over. Nothing dangerous was discovered — the replacement simply had evidence that held up.
What was measured
That a drug leaving practice implies it was found harmful — here it was displaced by a comparator with stronger evidence while remaining one of the safest molecules in respiratory medicine
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
The Cochrane review records that sodium cromoglycate was recommended as maintenance treatment for childhood asthma for many years and that its use decreased after 1990 when inhaled corticosteroids became popular, while still being used in many countries. The displacement was not driven by any safety signal: cromolyn remains among the best-tolerated drugs in respiratory medicine, and the Cochrane review of topical antihistamines and mast cell stabilisers in allergic conjunctivitis, which included cromoglicate, reported no serious adverse events for the class. What changed was the availability of a comparator whose evidence base did not depend on trials published between 1970 and 1997 with a funnel plot showing missing negatives. Every original brand — Intal, Opticrom, Crolom — has since left the active Drugs@FDA product listing.
Written into the record, not signed off as a reviewed claim
It is essentially not absorbed, and that is the design
In plain words
The molecule carries two permanent negative charges, so almost none of it crosses from the gut or the airway into the bloodstream. It can only act on the surface you put it on — which is why there are four different formulations for four different surfaces.
What was measured
Ionisation state and route-specific formulation set, from structure and regulatory listings
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
Cromoglicic acid is a symmetrical bis-chromone with two carboxylic acid groups, fully ionised at physiological pH, giving a doubly anionic molecule with negligible passive membrane permeability. The consequence runs through the whole product family: separate formulations exist for inhalation, nasal, ophthalmic and oral routes, and the oral concentrate is indicated for mastocytosis precisely because it acts on gut mucosal mast cells without being absorbed. It also explains the safety record — a drug that does not enter the circulation cannot produce systemic toxicity — and the dosing burden, since local concentration must be maintained by repeated application rather than by a plasma half-life.
Source
PubChem CID 2882, structure and physicochemical properties; Drugs@FDA route listings for cromolyn sodium (inhalation, nasal, ophthalmic, oral)
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
Across the eye-drop class it works, in the short term, like everything else
In plain words
In allergic conjunctivitis, the systematic review that examined every drop in this class found that all of them beat a dummy in the short term, including this one, and that none of them has any long-term data.
What was measured
Participant-reported ocular symptom severity against placebo, class-wide across 30 trials
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
The Cochrane review of topical antihistamines and mast cell stabilisers for seasonal and perennial allergic conjunctivitis identified 30 randomised trials in 4,344 participants across 17 drugs or comparisons, with nedocromil sodium and sodium cromoglycate among the agents evaluated. Overall risk of bias was low but reporting quality variable and outcome reporting highly heterogeneous; meta-analysis was possible for only one comparison, which did not involve cromoglicate. The conclusion was that all reported agents reduce symptoms and signs of seasonal allergic conjunctivitis against placebo in the short term, that trials evaluated treatment periods of one to eight weeks only with no long-term efficacy data, and that no serious adverse events related to the class were reported.
Written into the record, not signed off as a reviewed claim
The one indication where the target cell is beyond doubt is the smallest one
In plain words
For mastocytosis — a disease defined by too many mast cells — the oral form has its own approval. That is the only place where "mast cell drug" is not an assumption about the mechanism but a description of the disease.
What was measured
That a mast-cell-directed rationale transfers from mastocytosis, where the cell type defines the disease, to asthma, where the Cochrane review found no significant effect on symptom-free days
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
Gastrocrom, cromolyn sodium oral concentrate, was approved under NDA 020479 on 29 February 1996 and remains the only branded cromolyn product in the active Drugs@FDA listing, with generics from 2011 onward. In mastocytosis the pathology is an excess of mast cells, so the drug and the disease are matched at the level of the cell type regardless of which molecular mechanism turns out to be correct — the therapeutic rationale does not depend on resolving the GPR35 or annexin A1 question. This is a narrower and firmer claim than the one made for the inhaled product, where the same cell type is one participant among many in a complex inflammatory disease.
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What is not here
7 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.
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
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.
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.
A bis-chromone so poorly absorbed that it only works where it is sprayed — the drug that named the mast cell stabiliser class, whose mechanism its own pharmacologists called a mystery as recently as 2017, and whose Cochrane review of 23 trials in 1,026 children found no significant difference from placebo on symptom-free days with a funnel plot showing missing small negative studies.
Recorded evidence blocks (9)
Q1
On the Cromoglicic acid label: indicated for what?
"GASTROCROM is indicated in the management of patients with mastocytosis. Use of this product has been associated with improvement in diarrhea, flushing, headaches, vomiting, urticaria, abdominal pain, nausea, and itching in some patients.": indications and usage on Cromoglicic acid's label. DailyMed label · 00623958-a8fe-47d1-a0d2-0aa4e2f7966e · 2024-06-26
Q2
23 registered trials of Cromoglicic acid — at which phases?
Registered studies posting no result
20 of 23
23 registered studies of Cromoglicic acid: 10 phase2, 5 phase1, 4 phase3, 2 early phase1, 2 phase4, 1 na, 1 na or unstated. CLINICALTRIALS_SNAPSHOT · 2026-09-01
254 with a PubMed record
Show the evidence
phase2
10
phase1
5
phase3
4
early phase1
2
phase4
2
na
1
8 more recorded rows
na or unstated
1
completed
8
terminated
6
not yet recruiting
3
recruiting
3
enrolling by invitation
1
unknown
1
withdrawn
1
recorded 2026-09-01 · last checked 2026-09-04
Q3
7 of Cromoglicic acid's trials stopped: futility/efficacy, accrual/recruitment, other?
"prematurely terminated because of low recruitment"; 7 of 23 registered studies
Show the evidence
Trial
NCT01701843
terminated; "prematurely terminated because of low recruitment"
NCT01841307
terminated; "Difficulty recruiting; Funding ended; interim analysis provided sufficient data for interpretation."
NCT02664051
terminated; "Inactive"
NCT03202147
withdrawn; "Study halted prematurely prior to initiation but potentially will resume in the future."
NCT04408664
terminated; "Insufficient accrual rate"
NCT04428775
terminated; "Low enrollment"
1 further recorded trialNCT05077917
terminated; "slow enrollment"
recorded 2026-09-01 · last checked 2026-09-04
Q4
Human studies of Cromoglicic acid used Cromolyn Sodium (17.1 mg BID) — over how long?
Human studies of Cromoglicic acid used "Cromolyn Sodium (17.1 mg BID)". ClinicalTrials.gov · 2026-09-01
Show the evidence
humanNCT07142291
Cromolyn Sodium (17.1 mg BID)
recorded 2026-09-01 · last checked 2026-09-04
Q5
Which running trial of Cromoglicic acid could settle function?
NCT07757555 measures Change in Physical Function as Measured by the PROMIS® Physical Function Scale, reading out 2028-02-02.
1 open trial; n 25; "Guanfacine and Cromolyn Sodium for POTS: The DBPOTS Trial"
Show the evidence
TrialNCT07757555
"Guanfacine and Cromolyn Sodium for POTS: The DBPOTS Trial"; n 25; "Change in Physical Function as Measured by the PROMIS® Physical Function Scale"; 2028-02-02
Q6
Which 5 trials of Cromoglicic acid posted no result?
Posted no result
5 of 5 completed trials
Registrations
NCT00745199, NCT01722812, NCT02566252, NCT02547818 and NCT03167216
Completion dates
oldest 2009-06; newest 2022-06-30
Show the evidence
Trial
NCT00745199
2009-06
NCT01722812
2013-05
NCT02566252
2016-03
NCT02547818
2020-11-18
NCT03167216
2022-06-30
Q7
At the median, Cromoglicic acid's trials enrolled 21 people — anything larger?
Median enrolment
21
Largest enrolment
5000
Registered trials counted
22
Q8
What do 8 spontaneous reports say about Cromoglicic acid — 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.
Cromoglicic acid appears in spontaneous reports to regulators. Across the 1 most-reported reaction term, 8 reaction mentions were counted: treatment failure 8. FAERS via Open Targets · CHEMBL428880 · 2026-06-24
Show the evidence
treatment failure
8
recorded 2026-06-24 · last checked 2026-09-04
Q9
Which reaction does Cromoglicic acid's label not list?
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 · openFDA / DailyMed — US Government work
✗ 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: 6 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.