Cromolyn Has Very Few Drug Interactions — But You Should Still Be Informed

If you're starting Cromolyn Sodium and you take other medications, it's natural to worry about drug interactions. Here's the reassuring news upfront: Cromolyn has one of the cleanest interaction profiles of any prescription medication.

That said, there are still some things to be aware of. This guide covers how drug interactions work in general, what we know about Cromolyn's interactions (or lack thereof), and what you should always tell your doctor.

How Drug Interactions Work

Drug interactions happen when one medication affects how another medication works. This can happen in several ways:

• Absorption interactions: One drug changes how much of another drug gets into your body
• Metabolism interactions: One drug affects the liver enzymes that break down another drug (the cytochrome P450 system)
• Excretion interactions: One drug changes how quickly another is removed from your body
• Pharmacodynamic interactions: Two drugs have additive or opposing effects on the same system

Most significant drug interactions involve the liver's cytochrome P450 enzyme system. This is where Cromolyn gets its safety advantage.

Why Cromolyn Has So Few Interactions

Cromolyn Sodium is unusual among prescription medications because it has extremely low systemic absorption. When you take the oral solution, only about 0.5–2% actually enters your bloodstream. The rest stays in your GI tract and is excreted unchanged.

Because so little reaches your bloodstream:

• It is not metabolized by cytochrome P450 enzymes in the liver
• It does not inhibit or induce liver enzymes that process other drugs
• It has virtually no protein binding competition with other medications

This means Cromolyn is unlikely to change the levels or effectiveness of other medications you're taking — and other medications are unlikely to change how Cromolyn works.

Known Medication Interactions

According to current FDA labeling and drug interaction databases, no major drug-drug interactions have been identified for Cromolyn Sodium oral solution.

There are also no moderate interactions that would require dose adjustments or special monitoring when combining Cromolyn with other common medications.

This includes safe use alongside medications frequently taken by mast cell disorder patients:

• H1 antihistamines: Cetirizine (Zyrtec), Loratadine (Claritin), Fexofenadine (Allegra), Diphenhydramine (Benadryl), Hydroxyzine (Atarax/Vistaril)
• H2 antihistamines: Famotidine (Pepcid), Ranitidine (where still available)
• Leukotriene inhibitors: Montelukast (Singulair), Zafirlukast (Accolate)
• Mast cell stabilizers: Ketotifen
• Corticosteroids: Prednisone, Methylprednisolone
• Epinephrine auto-injectors: EpiPen
• Proton pump inhibitors: Omeprazole (Prilosec), Pantoprazole (Protonix)

Many patients with mastocytosis or MCAS take several of these medications simultaneously with Cromolyn without interaction concerns.

Supplements and OTC Medications to Watch

While Cromolyn doesn't have formal drug interactions with supplements or OTC medications, there are a few practical considerations:

Quercetin

Quercetin is a natural flavonoid supplement that some mast cell patients take as a complementary mast cell stabilizer. There's no known interaction with Cromolyn, and some patients use both. However, discuss this with your doctor as research on the combination is limited.

Vitamin C

Vitamin C acts as a natural antihistamine for some patients. No interaction with Cromolyn is known, but high-dose Vitamin C can cause GI symptoms (diarrhea, stomach upset) that could overlap with Cromolyn's GI side effects.

Digestive Enzymes

Some mast cell patients take digestive enzymes like DAO (diamine oxidase) supplements to help break down histamine in food. No interactions with Cromolyn are known, but take them at different times to avoid any potential effect on Cromolyn's absorption.

Antacids

Over-the-counter antacids (like Tums or Maalox) could theoretically affect the pH of your stomach and alter how Cromolyn dissolves. While this interaction hasn't been formally studied, it's a good idea to separate antacid use from Cromolyn doses by at least 30 minutes.

NSAIDs

Non-steroidal anti-inflammatory drugs like Ibuprofen (Advil) and Naproxen (Aleve) can trigger mast cell degranulation in some patients with mast cell disorders. This isn't an interaction with Cromolyn specifically — it's a concern for your underlying condition. Some mast cell patients are advised to avoid NSAIDs altogether. Talk to your doctor about safe pain relief options.

Food and Drink Interactions

While Cromolyn doesn't interact with specific foods at a pharmacological level, there are important rules about how you take it with food:

• Take Cromolyn 30 minutes before meals on an empty stomach for best results
• Mix the oral solution with water only — do not mix with fruit juice, milk, or food, as this can affect how the medication works in your gut
• Alcohol is not known to interact with Cromolyn, but alcohol can trigger mast cell degranulation in some patients. If alcohol worsens your symptoms, it's worth limiting regardless of Cromolyn use.

What to Tell Your Doctor

Even though Cromolyn has very few interactions, you should always tell your doctor about:

• All prescription medications you're currently taking
• Over-the-counter medications — including antihistamines, antacids, and pain relievers
• Supplements and vitamins — especially Quercetin, DAO enzymes, and high-dose vitamins
• Herbal remedies — some can affect mast cell activity
• Any changes to your medication regimen — if you start or stop a medication while on Cromolyn, let your doctor know
• Kidney or liver conditions — while Cromolyn has very low systemic absorption, small amounts are excreted renally, and dose adjustments may be appropriate

It's also important to mention if you're taking medications that are known to trigger mast cell activation. Your doctor can help you identify potential triggers and find safer alternatives.

Final Thoughts

Cromolyn Sodium stands out for having an exceptionally clean drug interaction profile. Its low absorption, lack of liver enzyme involvement, and local mechanism of action mean it plays well with the vast majority of other medications.

That said, always keep your healthcare team informed about everything you're taking. And if you're having trouble finding Cromolyn at your pharmacy, use Medfinder to check availability near you.

For more about this medication, see our guides on what Cromolyn is, side effects, and how it works.