Question
I keep reading reports that some people with ME/CFS also have a condition called mast cell activation syndrome (MACS). I also saw a report on the MEA website about a new Overlapping Illness Alliance being formed that includes ME/CFS, PoTS and MCAS. So what is MCAS? Can it be treated? And how common is it in people with ME?
Answer
Mast cells are a normal part of our body’s immune system that help us to fight infections. These cells are often involved in allergic or inflammatory reactions and, when activated, they release different chemicals, including histamines. Histamines create symptoms that relate to allergic reactions.
So MCAS is caused by abnormal mast cells or the abnormal release of chemicals contained within the mast cell.
The most common signs and symptoms of MACS, some of which obviously occur in ME/CFS* as well, are:
- Fatigue*
- Dermographism (a condition in which light scratching of the skin causes raised, red lines)
- Widespread pain*
- Feeling faint or fainting*
- Headaches*
- Itching/nettle rash
- Tingling*
- Nausea and/or vomiting
- Chills*
- Skin swelling, which moves around the body
- Eye irritation
- Breathlessness
Less common signs and symptoms include:
- Variable blood pressure
- Excessive heart rate
- Blocked nose
- Wheezing
- Flushing
- Diarrhoea
- Abdominal cramps
On rare occasions a severe allergic reaction can occur called anaphylaxis which includes rapid swelling of skin and tissues particularly around the mouth and airways. Triggers: Sometimes it's difficult to identify the cause of a mast cell reaction. If you do identify a trigger try to avoid this in future.
These are some of the more common triggers:
- Alcohol
- Heat
- Medication
- Medical procedures
- Wasp/bee stings or insect bites
- Fever or infection
- Physical stimulation (e.g. pressure, friction)
- Emotions/stress
- Foods
- Perfumes
- Bacteria/mould
- Menstrual cycle
Treatment options: Although there is no permanent cure for MCAS, management of the condition is based on avoiding triggers and medication to control symptoms.
Antihistamines can be used to dampen down the effect of histamine released by the mast cell. You may be asked to start taking a trial of dual antihistamines for three months. A dual regimen means that you will take two types of antihistamines daily. You will then be reviewed at three months to explore the effects on your symptoms.
- A recent research paper from Austria reported that mast cell activation appears to be a frequent and clinically-relevant comorbidity in ME/CFS and is associated with a higher prevalence of orthostatic intolerance, particularly POTS. Stratifying patients based on MCA involvement may support personalised treatment approaches and improve clinical outcomes.
- Mast Cell Action is a charity that provides more information on MCAS
- The British Dietetic Association (BDA): Low Histamine Diet Information
- More information on the Overlapping Illness Alliance
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MEDICAL DISCLAIMER
We recommend that the medical information is discussed with your doctor. It is not intended to be a substitute for personalised medical advice or treatment. You should consult your doctor whenever a new symptom arises, or an existing symptom worsens. It is important to obtain medical advice that considers other causes and possible treatments. Do not assume that new or worsened symptoms are solely because of ME/CFS or Long Covid.