MCAS // Treatment

There’s currently no cure for MCAS but a broad range of treatments are available. Treatment plans are designed to both control immediate symptoms and to stabilise mast cells longer-term. While individual treatment plans differ, most incorporate combination drug & supplement therapies, dietary changes and lifestyle modifications.

A two-pronged approach

A combination of prescription and over-the-counter drugs combined with nutritional supplements will likely form the basis of most MCAS treatments. This isn’t necessarily the desired starting point for many Doctors and patients but by the time an MCAS diagnosis is made symptoms are usually severe and seemingly uncontrollable - this means pharmaceutical interventions become something of a necessity in the first instance.

Drug and supplement regimens for MCAS typically have a dual goal:

  1. to provide immediate, effective symptom relief and

  2. to stop symptoms from developing longer-term by stabilising your mast cells.

To achieve this a number of medicines and supplements might need to be tried until you hit upon a combination that works for you. The important thing to remember here is that although finding the right treatment takes time, you have a lot of options.

Medicines

The list below highlights some of the medicines commonly used to treat MCAS (and mast cell diseases in general). It’s by no means an exhaustive list and your own treatment plan might include medicines not included here. Be aware that availability and restrictions may vary by region and/or country.

Commonly used medicines

  • Brand names
    Clarityn (UK) Alavert (US)

    Notes
    Commonly available without a prescription.
    May have fewer drug-drug interactions than other H1 antihistamines.

    Common side effects
    Drowsiness, dry mouth

  • Brand names
    Benadryl Allergy (UK)
    Zyrtec (US)

    Notes
    Commonly available without a prescription.

    Common side effects
    Drowsiness, dry mouth

  • Brand names
    Allevia, Treathay, Telfast (UK)
    Allegra (US)

    Notes
    Commonly available at lower strengths without a prescription.

    Common side effects
    Drowsiness, dizziness

  • Brand names
    Nytol Original, Boots Sleepeaze (UK)
    Benadryl (US)

    Notes
    A first generation H1 antihistamine. Effective for acute flares but has a sedative effect.

    Common side effects
    Pronounced tiredness / sedation

H1 Antihistamines

  • Brand names
    Pepcid (UK)
    Pepcid, Zantac 360 (US)

    Notes
    Not usually available without a prescription in the UK.

    Common side effects
    Constipation, diarrhoea, headache

  • Brand names
    Tazac, Axid (UK & US)

    Notes
    Not available without a prescription in the UK and US.

    Common side effects
    Constipation, diarrhoea, headache

H2 Antihistamines

  • Brand names
    Zaditen

    Notes
    There are frequent supply issues with this drug in the UK and you may have to swap from tablet to liquid or vice versa to ensure you have a supply.

    Common side effects
    Headache, conjunctivitis, upper airway inflammation

  • Brand names
    Nalcrom (UK)
    Gastrocrom (US)

    Notes
    A particularly expensive drug which may not be covered by health insurers.

    Common side effects
    Can cause acute mast cell flares when first administered but may reduce symptoms long-term.

Mast Cell Stabilisers

  • Brand names
    Singulair

    Notes
    May be particularly helpful at reducing wheezing and abdominal cramping.

    Common side effects
    Diarrhoea, fever, nausea, headache

Leukotriene Inhibitors

Non-Steroidal Anti-Inflammatories (NSAIDs)

  • Brand names
    Anadin (UK)

    Notes
    Many people with MCAS cannot tolerate NSAIDs and the use of aspirin to treat symptoms should be supervised by a healthcare professional.

    Aspirin (and other NSAIDs) should be avoided while you’re being tested for MCAS as they can influence lab results.

    Common side effects
    Can cause acute, and sometimes severe flares in some people.

    Indigestion, increased bleeding

Competitive Opioid Receptor Antagonists

  • Notes
    May improve a broad range of symptoms in those who can tolerate it.

    Common side effects
    Nausea, insomnia

MCAS Medicines

Just as Mast Cell Activation Syndrome itself requires a nuanced approach, so too does the approach to treating it with pharmaceutical medicine. Here are a few things worth bearing in mind…

4 things you should know

01.

Most medicines are used “off-label”

At present, no drugs have been specifically created or licensed for MCAS. This means Doctors have to prescribe drugs “off-label” which means they’re prescribing medicines that weren’t originally intended for MCAS but may be beneficial in treating it. As a result, MCAS won’t be described on the information leaflet that comes with your medicine. If you have questions, be sure to speak with the Doctor who prescribed your medicine.

02.

Another little MCAS gem is that the very medicines prescribed to help stop mast cell reactions can themselves cause a reaction! This can be incredibly disheartening when you’re desperate to feel better. However, before you give up on a medicine, speak with your Doctor about Titration as your starting dose may simply be too high. Titration is a way of limiting potential side-effects by starting you off on a very small dose and then slowly and steadily increasing it until you reach your target dose. Many MCAS patients find this approach helpful.

You might need to titrate your dose

03.

Ordinarily it shouldn’t matter whether you use a branded medicine or a generic form as the active ingredient (the drug) remains the same. However, when it comes to mast cell diseases like MCAS, the fillers, binders and dyes (excipients) used in the manufacturing process can also cause unwanted reactions. Some people find changing to a different brand of the same medicine (one that uses different excipients) can help reduce unwanted symptoms.

The brand matters

04.

Some medicines can be compounded

If you’ve been prescribed a medicine but are really struggling to find a form you can take without experiencing a reaction, you may be able to have the medicine compounded. A compounding pharmacy can tailor a medicine to your specific needs by removing unnecessary fillers or creating customised titration doses for example. Compounded medicines can be quite expensive but typically enable you to gain the benefits of medicines you wouldn’t otherwise be able to tolerate.

Supplements

The use of both pharmaceutical drugs and nutritional supplements is fairly common when treating MCAS and your specialist will likely recommend both. The table below highlights some of the most commonly recommended supplements for MCAS. Again, this list is not exhaustive and your doctor may recommend supplements not listed here.

Commonly used supplements

  • Notes
    Inhibits the release of mast cell mediators

    Outperforms sodium cromoglycate in blocking inflammatory cytokine release [1]

  • Notes
    The active component found in turmeric

    Inhibits the proliferation and function of mast cells

    Inhibits the production of mast cell mediators [2]

  • Notes
    Inhibits mast cell activation (degranulation)

    Enhances general immune system function

    May provide additional benefit in a timed-release form [3]

  • Notes
    Inhibits mast cell activation (degranulation)

    Promotes the production of anti-inflammatory cytokines

    Considered essential for the healthy function of mast cells [4] [5]

Mast Cell Stabilisers

  • Notes
    A digestive supplement

    Helps breakdown histamine in the digestive tract

    May be helpful for food-induced flares

Enzymes

HEADS UP: supplements can be just as problematic as prescribed medicines if you have MCAS so always check in with your Doctor before starting any new ones.

  • [1]
    Weng Z, Zhang B, Asadi S, Sismanopoulos N, Butcher A, Fu X, Katsarou-Katsari A, Antoniou C, Theoharides TC. Quercetin is more effective than cromolyn in blocking human mast cell cytokine release and inhibits contact dermatitis and photosensitivity in humans. PLoS ONE. 2012;7(3). doi: 10.1371/journal.pone.0033805.

    [2]
    Mathias C, Xing W, Kinney S, Mazzamurro J, Carlson L, Schneider S. Curcumin inhibits the development of food allergy by suppressing mast cell function in an NF-κB-dependent manner (HYP7P.308). J Immunol. 2014 May 1;192(1_Supplement):119.23. doi: 10.4049/jimmunol.192. Supp.119.23.

    [3]
    Kazama I, Sato Y, Tamada T. Pyridoxine synergistically potentiates mast cell-stabilizing property of ascorbic acid. Cell Physiol Biochem. 2022;56:282-92. doi: 10.33594/000000534.

    [4]
    Murdaca G, Allegra A, Tonacci A, Musolino C, Ricciardi L, Gangemi S. Mast cells and vitamin D status: A clinical and biological link in the onset of allergy and bone diseases. Biomedicines. 2022;10(8):1877. Available from: http://dx.doi.org/10.3390/biomedicines10081877.

    [5]
    Liu Z-Q, Li X-X, Qiu S-Q, Yu Y, Li M-G, Yang L-T, et al. Vitamin D contributes to mast cell stabilization. Allergy [Internet]. 2017;72(8):1184–92. Available from: http://dx.doi.org/10.1111/all.13110

DOES THE SUPPLEMENT BRAND MATTER?

Yes it does. Nutritional supplements aren’t regulated as strictly as medicines in most countries which means their quality, effectiveness and ingredients can vary wildly. If you’re in any doubt, your Doctor may be able to recommend specific brands that maximise the benefits while minimising the risk of unwanted reactions.