What is MCAS & Histamine Intolerance?

Is Your Body Being Dramatic Again?

You eat something completely normal.

Then your face gets hot. Your stomach starts protesting. Your head hurts. Your heart is racing and somehow your nose is involved too.

The symptoms seem unrelated. Histamine says otherwise.

Histamine is a natural chemical involved in immune response, digestion, brain function and more. Problems can happen when your body struggles to break histamine down efficiently or releases more than it can comfortably manage.

Histamine intolerance is generally linked to difficulty processing histamine, including histamine from food.

MCAS, or Mast Cell Activation Syndrome, involves mast cells releasing excessive chemical mediators, including histamine.

Different process. Similar chaos.

What Can Cause Histamine Problems?

There is not always one clear cause, but possible contributors may include:

• Poor histamine breakdown

• Low DAO enzyme activity

• Gut inflammation or digestive conditions

• Genetics

• Certain medications

• Alcohol

• Hormonal changes

• Infections

• Chronic stress

• Poor sleep

With MCAS, mast cells may become overly reactive and release inflammatory chemicals in response to triggers that would not normally cause a major reaction.

Sometimes there is an underlying cause.

Sometimes your body simply wakes up and chooses confusion.

Why Do the Symptoms Seem So Random?

Because mast cells and histamine receptors are found throughout the body.

Your skin has them.

Your gut has them.

Your nervous system, lungs and blood vessels have them too.

That means one issue can show up in several completely different places.

Possible symptoms may include:

Skin

• Flushing

• Hives

• Itching

• Rashes

• Swelling

• Feeling unusually hot

Digestion

• Bloating

• Nausea & vomiting

• Stomach pain

• Reflux

• Diarrhea & Constipation (Yes, apparently both.)

Head and Nervous System

• Headaches

• Migraines

• Brain fog

• Fatigue

• Dizziness

• Difficulty concentrating

Nose and Lungs

• Congestion

• Runny nose

• Sneezing

• Wheezing

• Shortness of breath

• Air Hunger

Heart and Circulation

• Heart palpitations

• Rapid heart rate

• Feeling faint

• Blood-pressure changes

Histamine-related symptoms can look completely disconnected because they affect multiple systems at once.

Your stomach hurts.

Your face is red.

Your nose is running.

Your heart is doing parkour.

And suddenly, the symptoms that never seemed related may not be so random after all.

Next Up: What is histamine?