Firstly, everyone should know that, antihistamines don’t actually reduce histamine release which is crucial for treating MCAS.

In one paragraph: antihistamines do not reduce histamine release; they block H1 and H2 receptors so symptoms are not felt, which is why Dr. Hoffman uses round-the-clock blockade every 12 hours. His typical average is levocetirizine 5 mg and famotidine 20 mg twice daily, with ketotifen 0.25 to 1 mg at night, alongside mast cell stabilizers, a low-histamine diet, gut support, and addressing infections, toxins and stress.

They only block histamine receptors, preventing you from feeling the symptoms. You may need a round-the-clock blockade of the H1 and H2 receptors, every 12 hours. Hence the approach is different when it comes to treating people with mast cell activation using best antihistamines.

Which antihistamines work best for mast cell activation syndrome

Histamine 1 blockers – hydroxyzine, doxepin, loratadine, fexofenadine, diphenhydramine, ketotifen, and cetirizine.
Histamine 2 blockers – famotidine (Pepcid, Pepcid AC), cimetidine (Tagamet, Tagamet HB), ranitidine (Zantac). Famotidine is chosen most often as it has fewer drug interactions than Tagamet).
Mast cell stabilizers – cromolyn, ketotifen (both a mast cell stabilizer and an H1 blocker), hydroxyurea, quercetin.
Leukotriene inhibitors – montelukast (Singulair), zafirlukast (Accolate)
Tyrosine kinase inhibitors.

H1 and H2 histamine blockers must be taken every 12 hours for maximum effect.

It may take up to 12 months to achieve maximum therapeutic effect. The doses may need to be increased to up to three times the recommended over-the-counter dosing.

How Dr. Hoffman uses antihistamines to treat mast cell activation

1) Eat a low-histamine diet

People with mcas should remove alcohol, smoked and cured meat, tinned fish, pickled and fermented foods, berries (strawberries being one of the worst culprits), citrus, nuts, chocolate, dairy, spinach, yeast, soy sauce, tomatoes and tomato products, preservatives, and vinegar. Also stop eating leftover food.

This will only reduce the incoming histamine and won’t affect the mast cell overactivity within the cells of the body. A comprehensive guide regarding the low-histamine diet can be found here.

2) Promote good gut health

Cut back on gut-damaging and inflammatory foods, and increase probiotics. Use a DAO enzyme, which goes under the generic name Umbrellux DAO – two tablets, 20 minutes before each meal.

3) Mast Cell Stabilizers

Stabilize mast cell release histamine with quercetin and vitamin C 500 mg – two tablets three times daily. We use a product called Natural-D Hist from Ortho Molecular Products.

4) Use H1 and H2 blockers every 12 hours

Use, on average, levocetirizine 5 mg twice daily and famotidine 20 mg twice daily.

5) Block nighttime histamine release with ketotifen or zaditen

0.25–1 mg at night. Excellent sleep aid, mast cell stabilizer, H1 antihistamine. Excellent treatment for eosinophilic esophagitis.

6) Treat any existing infections

Have a thorough examination done to identify and treat any potential infections in the body which are powerful mast cell triggers. Stool testing by Genova labs and Cyrex Lab Pathogen Testing (array 12) can be of assistance in identifying pathogens.

7) Identify and remove toxins and allergens

This could be heavy metals, mercury fillings, cosmetics, and household cleaners.

8) Nutrients that assist in the treatment

This includes vitamin B6, alpha lipoic acid, vitamin C and E, selenium, omega-3s, N-acetylcysteine (NAC), methylation donors like methyl-folate, SAMe, and riboflavin.

9) Herbs

Nigella sativa, butterbur, turmeric, ginger and peppermint.

10) Get into a solid routine

Getting high quality sleep and staying on schedule helps keep mast cells in check.

11) Reduce stress

Stress, through the action of corticotropin hormone, can activate your mast cells and cause them to destabilize and release mediators.

One of the best resources for how to deal with histamine and mast cell activation through nutrition and supplementation is the website and Facebook posts by Yasmina Ykelenstam www.healinghistamine.com.

It can be incredibly discouraging to feel so sick for so long and not find any answers. It is my hope that we continue to learn more about multisystem conditions such as MCAS and spread useful information so it may end up in the hands of those suffering.

Share this article with friends and family to help spread the word about mast cell activation syndrome and histamine blockers. They may discover it’s more than allergies that’s keeping them down.

Frequently asked questions

Do antihistamines reduce histamine release in MCAS?

No. Antihistamines only block histamine receptors, preventing the symptoms from being felt, which is why round-the-clock H1 and H2 blockade every 12 hours may be needed.

Which antihistamines are used for mast cell activation syndrome?

H1 blockers include hydroxyzine, doxepin, loratadine, fexofenadine, diphenhydramine, ketotifen and cetirizine. H2 blockers include famotidine, cimetidine and ranitidine, with famotidine chosen most often because it has fewer drug interactions than Tagamet.

What doses of H1 and H2 blockers does Dr. Hoffman use for MCAS?

Dr. Hoffman uses, on average, levocetirizine 5 mg twice daily and famotidine 20 mg twice daily. Doses may need to be increased to up to three times the recommended over-the-counter dosing.

How long do antihistamines take to work for MCAS?

It may take up to 12 months to achieve maximum therapeutic effect.

What are mast cell stabilizers for MCAS?

Mast cell stabilizers include cromolyn, ketotifen, hydroxyurea and quercetin. Dr. Hoffman uses quercetin with vitamin C 500 mg, two tablets three times daily, as Natural-D Hist from Ortho Molecular Products, and ketotifen 0.25 to 1 mg at night.

Is famotidine used for MCAS?

Yes. The article lists famotidine (Pepcid, Pepcid AC) as an H2 blocker for MCAS and the one chosen most often, because it has fewer drug interactions than Tagamet. Dr. Hoffman uses famotidine 20 mg twice daily on average, since H1 and H2 blockers must be taken every 12 hours for maximum effect.

Are Zyrtec and Pepcid used together for MCAS?

Cetirizine is among the H1 blockers and famotidine (Pepcid) is among the H2 blockers for MCAS. Dr. Hoffman pairs an H1 and an H2 blocker every 12 hours, using on average levocetirizine 5 mg twice daily and famotidine 20 mg twice daily.

Why take Zyrtec and Pepcid together?

Antihistamines do not reduce histamine release in MCAS. They only block histamine receptors. That is why Dr. Hoffman describes a round-the-clock blockade of both H1 receptors (with drugs such as cetirizine) and H2 receptors (with famotidine, or Pepcid) every 12 hours.