Mast Cell Activation Syndrome (MCAS): Symptoms, Causes and What to Do
By Dr. Cynthia Hall, ND
5 MIN READ
If you have been dealing with unexplained symptoms like fatigue, sensitivities to chemicals, skin reactions, sensitivity to foods or brain fog — you are not alone.
Many women in San Diego and across California experience persistent, complex symptoms that do not fit neatly into one diagnosis.
One often overlooked condition that may be contributing to these seemingly unrelated symptoms is Mast Cell Activation Syndrome (MCAS).
What is Mast Cell Activation Syndrome (MCAS)?
MCAS is a condition where mast cells — part of your immune system — become overactive and easily triggered to release inflammatory molecules.
These molecules are normally helpful in fighting infections and healing injuries. A key molecule that is released is histamine.
When released in excess, or at the wrong time, these molecules can lead to widespread symptoms throughout the body and in multiple systems.
MCAS Symptoms in Women
Symptoms can vary widely, come and go, and be seemingly unrelated — making MCAS difficult to recognize.
Common symptoms I see in practice are:
Skin
rashes
itchy skin
hives
flushing or redness
Neurological
Brain fog
Headaches
Tics
Dizziness
Digestive
Bloating and gas
Food senstivities
Nausea/vomiting
Abdominal pain
Systemic
Fatigue
Rapid heart rate
Anxiety
Fibromyalgia-like symptoms
Sensitivity to temperature, environment and chemicals
Sleep issues
Why MCAS Is Often Missed
MCAS can be difficult to diagnose because:
Symptoms affect multiple systems
Symptoms overlap with other conditions
Standard testing is unreliable and may not capture it
Many women are told their symptoms are stress-related or unexplained.
What Triggers Mast Cell Activation?
Triggers can vary from person to person but may include:
Infections (like Lyme disease and mycotoxin illness)
Certain foods high in histamine
Environmental exposures
Hormonal fluctuations
Stress
Chronic illness
Chronic inflammation
Want to learn more about Mycotoxin illness?
Read more here:
The Connection between MCAS and Hormones
Mast cells and hormones are closely linked.
Inflammation from mast cell activation can:
Disrupt hormone signaling
Affect menstrual cycles
Worsen PMS symptoms
Hormonal changes can also trigger mast cell activity, creating a cycle of symptoms.
MCAS and Chronic Inflammation
MCAS is often associated with chronic inflammation, which can impact:
Hormone balance
Immune regulation
Energy levels
This overlap is why MCAS is often seen alongside other chronic conditions.
A Root-Cause Approach to MCAS
Rather than focusing on only on symptom suppression, a comprehensive approach may include:
Identifying triggers
Supporting gut health
Addressing inflammation
Supporting detoxification pathways
Balancing hormones
Clearing infections
Each plan should be personalized based on symptoms and history.
When to Consider MCAS
You may want to explore MCAS if you:
Have unexplained, multi-system symptoms
React to foods or environmental triggers
Experience fluctuating or unpredictable symptoms
Feel like your symptoms don’t fit a clear diagnosis
Are not responding to current treatment plans as expected
What to Expect from Evaluation
A more comprehensive approach may include:
Detailed and robust health history
Symptom pattern analysis
Targeted lab testing
Support Options
MCAS management often involves a combination of:
Nutrition and lifestyle strategies
Targeted supplementation, herbal medicine and prescription medicine, as needed
Reducing triggers
Supporting overall immune balance
Final Thoughts
Mast Cell Activation Syndrome is complex - but for many women, it can be an important piece of the puzzle when symptoms don’t appear to connect fully.
With the right approach, it is possible to better understand your body and move toward more stable, consistent health.