If you are experiencing chronic allergy symptoms, cromolyn sodium might be a viable way to manage them.

Cromolyn sodium is a mast cell stabilizer commonly used in the management of allergy and asthma-like symptoms. It is also a treatment option for immune system conditions like mast cell activation syndrome (MCAS) and mastocytosis.

In this article, we cover the essentials of cromolyn sodium: breaking down why it’s used, how it works, its common side effects, and how to take it safely.

Here’s what you need to know.

What is cromolyn sodium, and how does it work?

Cromolyn sodium (sometimes referred to as just Cromolyn or its brand name Gastrocrom®) is a mast cell stabilizer. It’s derived from khellin, which is a natural extract from the Ammi visnaga herb.

The medication is primarily used to manage allergy-like symptoms by reducing the release of chemical mediators like histamine by mast cells. It’s typically used as a preventative treatment and may be taken regularly over the long term to help manage symptoms.

Mast cells, which are a type of white blood cell, play an important role in the body, acting as an alarm system. When triggered, they release chemical mediators like histamine, leukotrienes, and cytokines, which can cause inflammation, airway constriction, and allergy symptoms.

Cromolyn sodium reduces the release of chemical mediators like histamine by mast cells, which can ease the severity and frequency of unwanted symptoms. It’s a preventative therapy, so it often takes up to four weeks to notice a difference.

The United States Food and Drug Administration (FDA) has approved cromolyn sodium for the following conditions:

• Mild to moderate bronchial asthma
• Allergic rhinitis (hay fever)
• Certain allergic eye conditions (vernal conjunctivitis, keratitis, keratoconjunctivitis)

Cromolyn sodium may also be prescribed off-label to reduce severe food allergies and manage inflammatory bowel disease.

Cromolyn sodium for mast cell conditions

People with mast cell conditions such as mast cell activation syndrome and mastocytosis may also be prescribed cromolyn sodium.

In MCAS, mast cells release chemical mediators like histamine irregularly or too much. In mastocytosis, people have too many mast cells, leading to a high release of chemical mediators. This is why treatments that help stabilize mast cells can support symptom management.

In people with these conditions, cromolyn sodium may help reduce symptoms such as gastrointestinal discomfort, flushing, or allergy-like reactions.

How to take cromolyn sodium

Cromolyn sodium can be taken in four different ways:

• Oral solution
• Nasal spray
• Eye drops (ophthalmic solution)
• Inhalation solution (through nebulizer or inhaler)

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Oral solution

To take the oral solution of cromolyn sodium, you can use capsules or ampules of liquid. Here’s how to prepare each option:

Capsules

• Open the cromolyn sodium capsule(s) and pour the powder into a half glass of water.
• Stir the solution until completely dissolved.
• Add an additional half glass of water while stirring.
• Drink the entire glass to get the full dose of medication.

Ampules

• Break the ampule and pour the liquid into a glass of water, and stir until dissolved.
• Drink the entire glass to get the full dose of medication.
• Do not use an ampule if it’s cracked, or if the liquid is cloudy or discolored.

Only mix cromolyn sodium with water, not juices, milk, or food. Store both capsules and ampules at room temperature, avoiding moisture, direct sunlight, and heat.

Don’t freeze cromolyn sodium for later use.

Nasal spray

Cromolyn sodium nasal spray comes with a specialized nasal applicator:

• Before using, blow your nose to clear your nostrils.
• Insert the applicator into your nostril.
• Sniff once as you spray.
• Repeat this process in the second nostril to complete the dose.

Ophthalmic solution

To use the eye drop version of cromolyn sodium, follow these steps:

• Wash your hands.
• Tilt your head back and gently press your finger against the skin below the lower eyelid to pull it away from the eye.
• Drop the medication into that space.
• Release your eyelid and hold your eyes closed, not blinking.
• Keep your eyes closed for one to two minutes to let the medication fully absorb.

Do not touch the tip of the applicator to your skin, eyelid, or eye to keep it as clean as possible. 

Inhalation solution

To help manage asthma-like symptoms, cromolyn sodium can be inhaled through a nebulizer or aerosol inhaler. Follow these steps to get the full dose:

• Prime and test the inhaler to ensure it is working.
• Once set, take off the cap and hold the inhaler upright with the mouthpiece facing you.
• Shake the inhaler three to four times.
• Breathe out slowly, emptying your lungs.
• Place the mouthpiece in your mouth, tilt your head back, and breathe in through your mouth.
• Breathe for three to four seconds, press the canister, and continue breathing as it sprays.
• Hold your breath for up to 10 seconds to get the medication into your lungs.
• Rinse your mouth after use.

If your prescription involves more than one spray per dose, wait one minute before administering the next spray. An inhalation chamber can also be used if you struggle to use inhalers in this way. 

Side effects of cromolyn sodium

Cromolyn sodium can cause side effects. It’s generally well-tolerated and has a low toxicity risk, but it’s still important to monitor for side effects, especially when starting this drug.

The most commonly reported side effects include:

• Headache
• Diarrhoea

Other reported side effects include:

• Pruritus (itching)
• Nausea
• Myalgia (muscle pain)
• Abdominal pain
• Rash
• Irritability
• Malaise (feeling generally unwell)

Additional side effects have been reported in broader clinical use, particularly affecting the gastrointestinal system, such as:

• Diarrhea
• Nausea
• Abdominal pain
• Constipation
• Vomiting

Less commonly, side effects affecting other systems have been reported, including:

• Skin: rash, photosensitivity (sensitivity to light)
• Neurological: dizziness, skin flushing
• Psychological: anxiety, sleep disturbances
• Respiratory: difficulty breathing

In clinical studies of people with mast cell conditions, some side effects overlap with symptoms of the condition itself. This can make it tricky to distinguish between medication-related effects and underlying symptoms without tracking changes over time.

Life-threatening reactions can occur in rare cases. If you or another person taking a new medication struggles to breathe or communicate, call emergency medical services immediately.

Taking cromolyn sodium safely

Before taking cromolyn sodium, it’s important to disclose if you have a medical history of the following conditions:

• Kidney disease
• Liver disease
• A history of any strong allergic reactions
• You are breastfeeding, pregnant, or planning a pregnancy

Also, tell your doctor about any other medications you are taking to ensure there are no contraindications.
To reduce the risk of adverse effects, only take this medication as prescribed by your doctor. Don’t take more of the medication than instructed.

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Frequently asked questions

Is cromolyn sodium the same as Flonase?

No, cromolyn sodium and Flonase (fluticasone) are not the same medication.

While they both are available as nasal sprays used to treat allergy-like symptoms, cromolyn sodium is a mast cell stabilizer, while Flonase is a corticosteroid. They are different classes of drug and have different mechanisms of action.

How long does cromolyn sodium take to work?

Because cromolyn sodium is a preventative medicine, it takes time to notice changes in your symptoms. Cromolyn sodium can take up to four weeks to reach its full therapeutic benefit.

To better understand its impact and whether it’s working for you, we recommend keeping a detailed symptom journal to assess changes in your health.

Is cromolyn sodium hard to get?

Unfortunately, there is an ongoing cromolyn sodium shortage that is affecting the availability of the medication. Due to supply issues, manufacturing discontinuation, and an increase in demand, this shortage may impact your ability to access this treatment. 

Disclaimer: Human Health is a health tracking platform and does not provide medical advice, diagnosis, or treatment. The information on this site is intended to support, not replace, conversations with qualified healthcare professionals.

Sources:

1. Cromolyn sodium (2024)
2. Label: GASTROCROM, cromolyn sodium liquid, DailyMed
3. Cromolyn Sodium (2024) 
4. Cromolyn sodium oral solution, concentrate, The United States Food and Drug Administration
5. Cromolyn sodium nasal solution, MedlinePlus
6. Cromolyn (ophthalmic route), Mayo Clinic
7. Cromolyn (inhalation route), Mayo Clinic‍
8. Cromolyn sodium concentrate shortage update & tips to navigate a drug shortage, The Mast Cell Disease Society