Compounded Antihistamines for Mast Cell Activation Syndrome

Author: Bryana Gregory, PharmD., R.Ph.

Compounded Antihistamines for Mast Cell Activation Syndrome

Do you suffer from allergies? Allergy symptoms affect so many people and can make your life miserable. It’s no secret that in Houston, as well as other parts of the country, we’ve all been having a tough time with the high pollen counts lately. As a result, many of us have succumbed to the effects of allergy-related reactions.

If left unattended, allergenic reactions to the environment can lead to respiratory distress, inflammation and an eventual productive cough, putting you at an increased risk of infection. So we want to tell you about some compounded medications that can help you with your allergy symptoms.

First, let’s start with the basics. An allergy is an abnormal reaction by the immune system to normally occurring substances in the environment, such as pollen, pet dander, mold, dust, and food, to name a few.

Common Allergy Symptoms

  • Fatigue
  • Frequent headaches
  • Sneezing, postnasal drainage or itching of the nose
  • Frequent “colds”
  • Recurrent or chronic sinus infections
  • Recurrent yeast infections, jock itch or athlete’s foot
  • Dizziness
  • Itching, watering, redness or swelling of the eyes
  • Dark circles under the eyes
  • Recurrent ear infections
  • Recurrent cough or bronchitis
  • Tightness in the chest, wheezing or asthma
  • Eczema, skin rashes, itching or hives
  • Indigestion, bloating, diarrhea or constipation

Many people take allergy shots or sublingual allergy drops, and these allergy treatments help prevent symptoms by desensitizing you to the allergens to which you are reacting. It builds up blocking antibodies (IgG) which block the allergy reaction.

However, sometimes that is not enough.

What is a Mast Cell and its role in allergies?

When you inhale or ingest various substances, they cross the inner lining of the body and they enter your bloodstream as allergens. If you have a genetic predisposition towards allergy, your plasma cells, which are a form of white blood cells in the bloodstream, produce an abnormal antibody, called immunoglobulin E (IgE antibody) to these various allergens. These abnormal IgE antibodies circulate in the blood and bind to mast cells which are on the mucosal lining of the respiratory and gastrointestinal tract, causing the mast cells to die, rupture and spill their chemical contents directly into your tissues.

A mast cell is a type of white blood cell, which is a part of your immune system, that releases histamine and other chemical substances into your tissues during allergic reactions, causing local tissue swelling, inflammation and drainage. Mast cells are found in your connective tissue, under the skin, in the lungs, near blood vessels and lymph vessels, in nerves, and in the intestines.

What is Mast Cell Activation Syndrome?

Mast cell activation is a normal process to mitigate inflammation in the body, but chronic activation is not. Many people suffer greatly from the effects of Mast Cell Activation Syndrome (MCAS).

First recognized in 1991 and finally termed such in 2007, Mast Cell Activation Syndrome is a large, prevalent collection of illnesses resulting from mast cells which have been inappropriately activated but which, in contrast to the rare “mastocytosis,” are not proliferating, or otherwise accumulating, to any significant extent. The lifespan for most MCAS patients appears normal, but quality of life can be mildly to severely impaired absent correct diagnosis and effective treatment. (1)

Symptoms of Mast Cell Activation Syndrome


  • Food, drug, environmental, and chemical sensitivities
  • Sweats that come out of nowhere
  • Inflammation
  • Swollen lymph nodes
  • Hyperflexible joints


  • Itching
  • Skin is sensitive to the touch
  • Hair loss


  • Racing heartbeat after meals
  • Chest pains
  • Dizziness and lightheadedness when standing up


  • Constipation
  • Reflux
  • Malabsorption

Brain and Nervous System

  • Trouble recalling words
  • Migraines
  • Depression
  • Anxiety
  • Insomnia
  • Dizziness
  • Numbness/tingling in arms and legs

Other conditions that may be related to MCAS

  • Fibromyalgia
  • Other issues with the GI (gastrointestinal) tract like SIBO, SIFO, or leaky gut
  • Crohn’s disease
  • Type 2 diabetes
  • Ehlers-Danlos Syndrome (EDS)
  • Postural Orthostatic Tachycardia Syndrome (POTS)
  • Autism spectrum disorders
  • Autoimmune diseases
  • Rheumatoid arthritis
  • Lupus
  • Hashimoto’s thyroiditis
  • Guillain- Barré syndrome
  • Graves
  • Sjogren’s
  • Multiple sclerosis

Does Mast Cell Activation Syndrome make allergies or allergy symptoms worse? If so, how?

In people with MCAS, mast cells are overactive and cause more severe allergic reactions. (Also, MCAS is keeping the body in a chronic state of inflammation so it doesn’t allow it to fully recover to defend against allergies.)

Our Compounded Antihistamines

At Physicians Preference Pharmacy, we compound antihistamines, that when used alone or in combination with allergy treatments, are highly effective against the effects of MCAS. Our compounded medications are always free of unnecessary dyes, binders or fillers, and our compounds contain the active ingredient and only the necessary filler for accurate and consistent dosing – hypromellose and/or microcrystalline cellulose.

The compounded antihistamines we offer include:

  • Famotidine capsules
  • Loratadine capsules
  • Diphenhydramine slow-release capsules
  • Brompheniramine slow-release capsules
  • Chlorpheniramine slow-release capsules
  • Hydroxyzine capsules
  • Ketotifen capsules

Why are our compounded antihistamines better than store-bought over-the-counter antihistamines?

Besides being free of unnecessary dyes, binders or fillers, one important point is that people with MCAS are SO sensitive that they react to literally almost everything. So typically, if they took a commercially available/over-the-counter product, they would likely react to the inactive ingredients or fillers. We actually refer to our antihistamines as hypoallergenic.

We Are Here to Help

Our compounded antihistamines do require a prescription from your provider. Please call our pharmacists today with any questions about your compounded prescription needs at 281-828-9088. It will be our privilege to serve you!


  1. Presentation, Diagnosis, and Management of Mast Cell Activation Syndrome