A few notes from the article I linked to:
This post discusses medications used to treat MCAS. Doses listed are taken directly from “Presentation, diagnosis and management of mast cell activation syndrome” by Lawrence B. Afrin. These doses are general recommendations. Medication should always be taken under the direction of a provider who knows you and your case personally.
MCAS is generally treated identically to ISM, with the medications that block the action of released mediators, that prevent the release of mediators or that prevent the production of mediators. As a reminder, any medication that causes a reaction should be evaluated to see if it is truly caused by the drug or by a dye or inert ingredient. Medications compounded without dyes or noxious fillers can be truly life changing for mast cell patients.
Antihistamines are first line medications for both acute and chronic management of MCAS (but not for anaphylaxis – epinephrine is first line medication for anaphylaxis.) Most currently available antihistamines either block the histamine 1 (H1) receptor or the histamine 2 (H2) receptor and are referred to by the receptors they block. It is generally recommended for MCAS patients to take medication to block H1 and H2 receptors daily as baseline medications.
Quercetin is commonly mentioned as a natural/homeopathic mast cell stabilizer. After much research on the topic, I have to say that I agree. It has been found to inhibit lipoxygenase and cyclooxygenase, which in turn decreases production of leukotrienes and histamine. It is usually dosed starting at 500-2000mg per day, divided up into 2-4 doses. For example, a daily dose of 500mg may be taken as 125mg four times a day. A newer form, quercetin chalcone, is usually taken at 250mg three times a day.
Corticosteroids like prednisone are sometimes used to manage MCAS symptoms. These medications can prevent mast cells from producing mediators and as such can be very effective. However, long term use can have severe side effects and as such is discouraged.