What are some conditions that may be connected to or co-occur with mast cell activation syndrome?

Mast cell activation syndrome (MCAS) has been associated with a number of conditions or disorders. The relationship between MCAS and these conditions can vary greatly, with some people having a number of these related conditions and some people having only MCAS. More research is needed to gain a full understanding of the mechanisms involved and potential causes of the connection or co-occurrence of certain health problems and MCAS. Clinically, we and our colleagues see many related conditions. Some conditions that may be linked or co-occur with MCAS include:

Ehlers-Danlos syndrome (EDS): EDS is a group of genetically related connective tissue disorders. MAS is frequently found in individuals with EDS, suggesting a potential link that is still being explored in the scientific community. There are 13 different forms of EDS, 12 of which can be tested for, although the most common, the hypermobile type, is a clinical diagnosis.

Postural Orthostatic Tachycardia Syndrome (POTS): POTS is a form of dysautonomia. It is characterized by an abnormal increase in heart rate upon standing. MCAS has been observed in a significant number of individuals with POTS, suggesting a potential connection. MCAS, EDS, and POTS are often seen together, referred to as the POTS-EDS-SAM Triad.

Gastroparesis and SIBO: Gastroparesis refers to a decrease in stomach and intestinal peristalsis that may be due to dysautonomia or other conditions, leading to an overgrowth of bacteria or fungi. Autoimmune conditions: Autoimmune conditions refer to immune dysfunction, where the immune system attacks itself. Hashimoto's thyroiditis, celiac disease, lupus, and Crohn's disease are types of autoimmune conditions. Autoimmunity comprises the 5th condition in Pentad patients. Any autoimmune condition qualifies patients to be considered Pentad patients.

Chronic Fatigue Syndrome/Myalgic Encephalomyelitis (CFS/ME): CFS/ME is a complex disorder characterized by severe fatigue, pain, confusion, other cognitive problems, and other symptoms. MCAS has been reported in many patients with CFS/ME.

Fibromyalgia: Fibromyalgia is a chronic pain condition characterized by widespread musculoskeletal pain, fatigue, and sleep disturbances. There appears to be a higher prevalence of MCAS in individuals with fibromyalgia.

Irritable Bowel Syndrome (IBS): IBS is a gastrointestinal disorder characterized by abdominal pain, bloating, and altered bowel habits. MCAS can affect your gut health and may trigger IBS or other digestive problems.

Allergies and Asthma: Allergies are an exaggerated immune response to substances that are normally harmless to most people. Asthma is a chronic respiratory condition that affects the airways, characterized by inflammation and narrowing of the airways, causing breathing difficulties. MCAS can co-exist with or trigger allergies and asthma.

Histamine intolerance: As we’ve discussed, histamine intolerance is characterized by a buildup of histamine in the body. MCAS can cause histamine intolerance, and many patients have both.

Multiple chemical sensitivity (MCS): MCS is a condition in which patients become ill due to environmental exposure to a variety of chemicals and toxins that would not be a problem for the general population. MCS can be characterized by increased mast cell activation, and many people with MCS also have MCAS.

I want to emphasize that having MCAS does not mean you will have all or any of these conditions. It simply means that if you have MCAS, you may be more likely to have them. Everyone’s experience with MAS is different. The types and severity of symptoms, co-occurring conditions, and underlying problems can differ from person to person. Proper diagnosis and treatment by a healthcare professional who specializes in mast cell disorders is crucial.