What does sodium cromoglicate do? A deep dive into its use and pharmacology

October 7, 2025 •

4 min read

Unlike medications that treat allergic symptoms reactively, sodium cromoglicate works proactively by preventing the release of inflammatory chemicals. This preventative action is key to understanding what does sodium cromoglicate do for conditions like asthma, hay fever, and allergic conjunctivitis.

Quick Summary

As a mast cell stabilizer, sodium cromoglicate inhibits the release of inflammatory substances, providing prophylactic treatment for allergic rhinitis, conjunctivitis, and asthma.

Key Points

Mast Cell Stabilizer: Sodium cromoglicate prevents allergic reactions by stabilizing mast cells, inhibiting the release of inflammatory chemicals like histamine.
Prophylactic Action: It is a preventative medication and is not effective for treating acute, ongoing allergy or asthma attacks.
Multiple Formulations: The medication is available as eye drops for allergic conjunctivitis, a nasal spray for allergic rhinitis, and oral capsules for systemic mastocytosis.
Delayed Onset: It requires consistent use for several days to weeks to achieve maximum effectiveness, especially for oral or nasal formulations.
Good Safety Profile: Sodium cromoglicate is generally well-tolerated with rare, mild side effects like local irritation, sneezing, or headache.
Not a Steroid: Unlike corticosteroids, sodium cromoglicate works through a different anti-inflammatory mechanism and is not a steroid.

The Core Mechanism of Sodium Cromoglicate

Sodium cromoglicate, also known as cromolyn sodium, is a mast cell stabilizer. The mechanism of action is central to understanding its role in allergy and asthma management. Mast cells are a type of immune cell that play a critical role in allergic responses. When an allergic trigger, such as pollen or dust mites, binds to antibodies on the mast cell surface, it causes the mast cell to 'degranulate,' or release a host of inflammatory mediators. These mediators include histamine, leukotrienes, and other cytokines, which are responsible for the unpleasant symptoms of allergies like itching, swelling, and mucus production.

Sodium cromoglicate's primary function is to stabilize the membrane of these mast cells. By doing so, it prevents the cascade of events that leads to degranulation, thereby stopping the release of inflammatory chemicals before they can cause symptoms. This preventative approach distinguishes it from other allergy medications, such as antihistamines, which work by blocking the effects of histamine after it has already been released. Because it prevents the allergic reaction rather than treating it, sodium cromoglicate must be taken regularly and before exposure to the allergen for optimal effect.

Applications of Sodium Cromoglicate in Allergic Conditions

The medication's prophylactic nature makes it a valuable treatment for various allergic diseases, depending on its formulation.

For Respiratory Allergies (Asthma and Rhinitis)

Asthma Management: Inhaled sodium cromoglicate has been historically used as a preventative therapy for mild to moderate asthma. It is particularly effective for managing exercise-induced asthma and asthma triggered by allergens. It is not a rescue inhaler and should never be used for an acute asthma attack. Some studies also indicate it can be an effective add-on therapy for patients with severe atopic asthma already on inhaled corticosteroids.
Allergic Rhinitis: Available as a nasal spray, sodium cromoglicate is used to prevent and relieve symptoms of hay fever and other nasal allergies. It reduces symptoms like sneezing, itchy nose, and a runny or stuffy nose.

For Ocular Allergies (Allergic Conjunctivitis)

Eye Drops: As ophthalmic eye drops, sodium cromoglicate is a popular treatment for allergic conjunctivitis. This includes conditions caused by hay fever, dust mites, and pet dander that result in red, watery, itchy, and puffy eyes. It is often considered a first-line treatment for managing these eye allergy symptoms.

For Systemic Mastocytosis

Oral Solution: An oral formulation is prescribed to manage the gastrointestinal symptoms associated with mastocytosis, a rare condition caused by an overaccumulation of mast cells. By stabilizing mast cells in the gut, it can help reduce abdominal pain, diarrhea, nausea, and other related issues.

Comparison: Sodium Cromoglicate vs. Antihistamines

Understanding the differences between mast cell stabilizers like sodium cromoglicate and antihistamines is crucial for effective treatment planning. While both are used for allergies, their mechanisms and ideal applications differ significantly.


Feature	Sodium Cromoglicate (Mast Cell Stabilizer)	Antihistamines
Mechanism	Stabilizes mast cell membranes, preventing the release of histamine and other inflammatory mediators.	Blocks the action of histamine at receptor sites after it has been released.
Primary Use	Prophylactic (preventative) treatment of allergic reactions and asthma.	Symptomatic treatment for acute allergic reactions and relief of ongoing symptoms.
Onset of Action	Requires consistent use for several days to weeks to achieve maximum effect.	Provides relatively rapid relief of acute symptoms.
Best For	Managing chronic, recurring allergies and prophylactic asthma control.	Quick relief of sudden or seasonal allergy symptoms.
Acute Attacks	Ineffective for treating acute allergic reactions or asthma attacks.	Some formulations can offer fast relief for immediate symptoms.
Potential Synergies	Can be used to reduce the need for supplementary oral antihistamines or corticosteroids over time.	Primarily used for reactive symptom control.

Considerations for Use

For sodium cromoglicate to be most effective, patients must adhere to the prescribed dosing schedule, as its effects are not immediate.

Consistency is Key: Because it prevents the allergic response, the medication needs to be taken regularly, even when symptoms are not present. Missing doses can reduce its effectiveness.
Administration: The method of administration depends on the condition being treated.
- Eye Drops: For allergic conjunctivitis, drops are placed directly into the eye.
- Nasal Spray: For allergic rhinitis, the spray is inhaled into each nostril.
- Oral Solution: The oral capsules are taken before meals for systemic mastocytosis.
- Inhalation: Historically used for asthma, this formulation has been largely replaced by more convenient options but is still available in some regions.
Contact Lenses: Individuals using sodium cromoglicate eye drops should typically remove contact lenses before administration and wait a specified time before reinserting them.

Side Effects and Safety Profile

Sodium cromoglicate has a generally favorable safety profile, with side effects typically being mild and transient. Due to its poor systemic absorption, particularly with ocular and nasal formulations, severe adverse reactions are rare.

Common side effects, which vary depending on the formulation, may include:

Eye Drops: Transient stinging or burning in the eyes.
Nasal Spray: Nasal itching, sneezing, or mild throat irritation.
Oral Solution: Mild gastrointestinal issues like nausea, diarrhea, or stomach pain, especially early in treatment.

Serious allergic reactions to sodium cromoglicate are rare but require immediate medical attention. It is not a steroid and does not carry the same risks associated with long-term corticosteroid use.

Conclusion: The Role of Prophylaxis

Sodium cromoglicate is a cornerstone of preventative treatment for various allergic diseases. By stabilizing mast cells and halting the release of inflammatory mediators, it effectively manages conditions like allergic rhinitis, conjunctivitis, and asthma before symptoms fully develop. Its non-steroidal mechanism and favorable safety profile make it a valuable alternative or complementary treatment to antihistamines and corticosteroids. However, patients must commit to consistent, regular use for optimal results, as it is designed for prophylaxis rather than the reactive treatment of acute symptoms. Consulting a healthcare provider is essential to determine if sodium cromoglicate is the right treatment option for a specific allergic condition.

For more information on the use of this medication for hay fever, you can visit the NHS - About sodium cromoglicate eye drops.

Frequently Asked Questions

No, sodium cromoglicate is not a steroid. It is a mast cell stabilizer, which works by a different mechanism to prevent allergic reactions from occurring in the first place.

Sodium cromoglicate is not for immediate relief. For eye drops, relief may be noticed within a few days to weeks. For nasal or oral forms, it may take up to 4 weeks of consistent, regular use to achieve its full effect.

Side effects are typically mild and uncommon. They can include transient stinging or burning with eye drops, sneezing or throat irritation with nasal spray, and mild gastrointestinal issues with the oral solution.

No, sodium cromoglicate is a preventative treatment and is not effective for relieving an acute asthma attack. A rescue inhaler should be used for this purpose.

Yes, sodium cromoglicate is safe to use with most antihistamines. In some cases, it may even help reduce the need for supplementary oral antihistamines.

The frequency depends on the condition and formulation, but it often requires regular use, such as four times a day, to be effective. It must be taken consistently for best results.

Some formulations, like certain eye drops and nasal sprays, may be available over-the-counter. However, oral capsules typically require a prescription.

If you forget a dose, take it as soon as you remember, unless it is almost time for your next scheduled dose. In that case, skip the missed dose and continue with your regular schedule. Do not take a double dose.