Cromolyn sodium

Mast cell stabiliser · also known as Cromoglicic acid, Sodium cromoglycate, Gastrocrom

Oral mast cell stabiliser with randomized systemic-mastocytosis evidence and a five-person retrospective MCAS case series.

How it relates to mast cells: MCAS patients
Types of studies cited: Case series
Approved in the US for: mastocytosis
Randomised trials in: systemic mastocytosis

What this relationship means: Studied in people diagnosed with mast cell activation syndrome. Current evidence consists of case reports, uncontrolled series, or retrospective review rather than randomised comparisons — so it establishes that people have taken it, not that it worked. A 2025 practical-management review places this at step 4 of the sequence it describes — described for persistent gastrointestinal symptoms despite H1 and H2 blockade. That is what the review reports, not a recommendation from this site.

Mechanism of action

Cromolyn sodium inhibits the release of preformed mediators from mast cell granules, and is the compound from which the “mast cell stabiliser” class takes its name — it descends from khellin, isolated from Ammi visnaga. The precise molecular target remains contested; reviews of the class note that cromolyn’s stabilising effect was characterised clinically well before its mechanism was, and that several proposed targets have not been settled.

A 2026 retrospective case series described five people who also had ME/CFS and met consensus-2 MCAS criteria. The patients were not a random or consecutive sample, there was no comparator, symptoms and wellness were self-reported, assessment varied by clinician, and the report mixed oral and local cromolyn routes. It therefore supplies direct MCAS-labelled exposure while remaining unable to establish an attributable outcome.

The randomized evidence remains a small withdrawal trial in systemic mastocytosis rather than MCAS. Oral cromolyn is minimally absorbed from the gut, while its US label covers mastocytosis and describes both gastrointestinal and non-gastrointestinal manifestations. The label does not carry a mast cell activation syndrome indication; use in MCAS is off-label.

Sources

Cromolyn sodium in the management of systemic mastocytosis Peer-reviewed study 1990 PMID 2110198 · link checked 24 Aug 2026
A Continuous Oral Regimen of High-Dose Cromolyn Sodium Is Effective for Some Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) Patients With Mast Cell Activation Syndrome Peer-reviewed study 2026 PMID 41728426 · link checked 24 Aug 2026
GASTROCROM (cromolyn sodium oral concentrate) US prescribing information Drug label · link checked 24 Aug 2026
Mast cell stabilisers Review article 2016 PMID 26130122 · link checked 24 Aug 2026
Mast Cell Activation Syndrome and Mastocytosis: Initial Treatment Options and Long-Term Management Review article 2019 PMID 30961835 · link checked 24 Aug 2026

What this evidence cannot establish

The direct MCAS report is a nonconsecutive, five-person retrospective case series in people who also had ME/CFS and met consensus-2 criteria. It was selected to illustrate a particular administration approach, used self-reported outcomes assessed at each clinician's discretion, mixed oral and local routes, and had no comparator; natural fluctuation, placebo effects, selection, attention from specialist clinicians, and concurrent care cannot be separated from cromolyn exposure. The randomized evidence is instead in systemic mastocytosis: a small multicentre withdrawal trial in a clonal mast cell disease with different diagnostic and proliferative biology. Oral cromolyn is minimally absorbed, so evidence for gastrointestinal effects does not imply a systemic one.

What this page does not say

No dosing, and no claim that this works. The entry describes a published mechanism, the cited study types, and what those studies cannot establish — nothing further. Why the site is built this way.

Recently verified. Verified 24 Aug 2026