Mast Cell Activation Syndrome (MCAS)

Mast Cell Activation Syndrome occurs frequently with the hypermobile type of EDS and is also often a part of the complex together with POTS. This combination of diseases came into focus of some researchers and hopefully the connection will be solved soon.

MCAS is not the same as Mastocytosis. Mastocytosis is a disease where mast cells start to proliferate in abnormal numbers in different tissue, whereas MCAS is a disorder where mast cells release mast cell mediators. But both disorders often lead to similar symptoms. MCAS can affect every system of the body and may manifest with neurological, gastroinstestinal, cardial, skin and bronchial symptoms.

Symptoms occur in different severity if mast cells start to degranulate through many triggers.

Symptoms which may occur:

Rash, Redness, Itching
Low body temperature
Diarrhea, nausea, cramps
Vision problems
Low bone density
Intolerance to foods or medication
Urinary urgency
sometimes even anaphylactic reactions

Basically the same symptoms like allergic reactions

Trigger factors which can lead to acute episodes:

Heat or cold
Physical activity
Chemicals / Medication

No alcohol!


Diagnosis of MCAS is very difficult. Based on a medical history regarding to typical mast cell specific symptoms a doctor will probably order lab tests for mast cell mediators like

Tryptase in blood
Methylhistamine in urine
Heparine in blood

or other markers (like Chromogranine A, Leuktrienes, Prostaglandine D2)

There are no clear criteria for diagnosing MCAS and although the patient does have MCAS all tests can come back negativ.

Often the doctors try a therapy consisting of a combination of H1 and H2 receptor blocker and mast cell stabilizers.

Foods with high levels of histamine, alcohol, specific medication and therapies which stimulate the immune system should be avoided (if possible) if MCAS is diagnosed.


Helpful Smartphone Apps for histamine free diet:


Emergency information in case of surgery:

In case of a surgery many factors can contribute to the release of mast cell mediators for example mental stress, bleeding, hypothermia and different medication. This is why it is very important to plan your pre-, peri-, and postoperative care very well.

In case of any surgery or invasive examination Prednisolone, H1 and H2 blockers should be administered as a mast cell prophylaxis.

The patients stress should be reduced as far as possible; the medication before, during and after surgery (pain meds, anesthesia, antibiotics, muscle relaxants) should be discussed and planned very well in advance.

A mast cell specific blood analysis for bleeding or thrombosis is necessary.

During the surgery the patient should be protected from hypothermia, skin irritation and a atraumatic technique should be used. Anaphylaxis can occur at all times and preventive measures have to be taken (Adrenaline, Glucocorticoid, H1 Antihistamines, Volume substitute). Patients who suffer from increased bleeding could benefit from Tranexamic acid.

After surgery anaphylaxis still can occur and should be monitored as well as a prophylaxis of thrombotic events.


Many drugs have a huge influence on mast cell diseases. Medication that should be avoided and their alternatives are the following:
(No claim for completeness or correctness)

Antibiotics to be avoided:
Cefotiam, Cefuroxime, Chlortetracycline, Clavulanic acid, D-Cycloserin, Framycetin (Neomycin), Isoniazid, Polymyxin B
Alternative: Roxithromycin

Local anesthesia: In general the ester type anesthesia are not well tolerated. Amid type anesthesia is better.

Anesthesia to be avoided: Curare, Methohexital, Phenobarbital, Propanidid
Alternative: Propfol, Ketamine

Muscle relaxants to be avoided: Alcuronium, Atracurium, Doxacurium, Gallamine, Metocurine, Mivacurium, Pancuronium, Succinylcholine (Suxamethonium), Tubocurarine
Alternative: Cisetracurium, Vecuronium, Rocuronium

Heart and blood pressure medication to be avoided: Alpha and Betablocker (for example Alprenolol), Chinidin, Dihydrazaline, Furosemide, Propafenone, Reserpine, Verapamil

Cough and asthma medication to be avoided: Acetylcysteine, Ambroxol, Aminophylline, Codeine, Theophylline

Anti-cramping medication to be avoided: Metoclopramid, Papaverin, Pilocarpine, Scopolamin

Opiate/Opoids to be avoided: Morphium, Codeine, Pethidine
Alternative: Remifentanil, Alfentanil, Fentanyl, Oxycodone, Piritramide, Tramadol

Other pain meds to be avoided: Acemitacin, Acetylsalicyl acid, Diclofenac, Flurbiprofen, Indometacin, Ketoprofen, Meclofenamic acid, Mefenamic acid, Naproxen, Noscapine, Pyrazolone, Sufentanil, Toradol (Ketorolac)
Alternative: Ibuprofen, Fenbufen, Levamisol, Paracetamol, Cannabinoids

Antipsychotics to be avoided: Bupropion, Carbamazepine, Diazepam, Diphenhydramine, Flunitrazepam, Thiopental
Alternative: Chlorpromazine, Haloperidol, Amitryptiline, Doxepin, Clomipramine, Maprotiline, Clonazepam, Triazolam, Oxazepam
Basically antipsychotic medication releases mast cell mediators if administered in therapeutic concentration.

Contrast to be avoided: Contrast dye with idodine (ionic), Gadoliniumchelate
Alternative: Non ionic contrast dye or mast cell prophylaxis with Prednisolone, H1 und H2 Blocker

Other things to be avoided: Latex gloves, Ethanol (caution with ethanol in medication)

Albumin solution, NaCl and Ringers solution could be used as plasma substitute.


MCAS patients who already had anaphylaxis should always carry an emergency kit with them, containing the following for example:

Ceterizine or Fenistil liquid, Celestamine N liquid and in the case of occuring breathing and circulatory issues an additional epinephrine pen like Fastject Autoinjektor (learn how to use the pen!) has to be carried with you.

For patients with asthmatic issues an inhaler containing Salbutamol helps.


Emergency medication MCAS





Sido B, Dumoulin FL, Homann J, Hertfelder HJ, Bollmann M, Molderings GJ. Chirurgische Eingriffe an Patienten mit Mastzellüberaktivitätserkrankung. Der Chirurg. 2014 Apr 1;85(4):327-33.

Pöhlau D, Raithel M, Haenisch B, Harzer S, Molderings G. Neurologische und psychiatrische Symptome der systemischen MCAD. NeuroTransmitter. 2015 Ausgabe 9.

The Mastocytosis Society


Brockow K, Metcalfe DD. Mastocytosis. Current opinion in allergy and clinical immunology. 2001 Oct 1;1(5):449-54.

Afrin LB, Pöhlau D, Raithel M, Haenisch B, Dumoulin FL, Homann J, Mauer UM, Harzer S, Molderings GJ. Mast cell activation disease: an underappreciated cause of neurologic and psychiatric symptoms and diseases. Brain, behavior, and immunity. 2015 Nov 30;50:314-21.

EDNF presentation of Prof. Anne Maitland