Mast Cell Activation Syndrome and gastrointestinal symptoms

If you’ve ever dealt with tummy pain, feeling sick, bloating, or unpredictable trips to the loo, you’re not alone. These gut symptoms are incredibly common and can happen for all sorts of reasons—sometimes there’s an obvious cause, like an infection or food intolerance, and sometimes the reason is a total mystery. For some people, these gut problems don’t go away, even after lots of tests and treatments.

One condition that’s getting more attention lately is Mast Cell Activation Syndrome (MCAS). While it might sound complicated, MCAS is simply when certain immune cells in your body become a bit too active. They then release chemicals that can cause all sorts of symptoms, including those stubborn gut troubles.

In this blog, we’ll break down what MCAS is and why it matters for your digestive health. We will also look at what you can do if you think it might be affecting you or someone you care about.

Five key takeaways

1. Gut symptoms are common in MCAS: Many people with mast cell activation syndrome experience tummy pain, nausea, vomiting, constipation, or diarrhoea—sometimes even when other causes can’t be found.
2. MCAS may be mistaken for other gut problems: MCAS symptoms are often confused with conditions like IBS, making diagnosis tricky.
3. Mast cells play a big role in gut pain: Chemicals released by mast cells can make pain nerves in the gut extra sensitive, leading to discomfort and pain.
4. SIBO is more common in MCAS: Small intestinal bacterial overgrowth can worsen gut symptoms and is found more often in people with MCAS.
5. Treatment options are available: Medicines called mast cell stabilisers, such as ketotifen, may help manage symptoms, and are available from Courier Pharmacy.

Could mast cell activation syndrome be responsible for functional gastrointestinal disorders?

Many people experience tummy troubles like pain, feeling sick, vomiting, or constipation. These symptoms can happen for lots of reasons, such as a blockage in the gut or inflammation [1], [2]. But sometimes, they show up even when doctors can’t find a clear cause [3].

These gut problems can also be linked to other health issues, like hormone, nerve, or tissue disorders. This demonstrates how closely the gut is connected to the rest of the body.

In the past, when doctors couldn’t find a clear cause, these symptoms were called “functional gastrointestinal disorders.” Now, they’re often called “disorders of gut-brain interaction,” because the signals between the brain and gut play a big role [4].

Recently, doctors have noticed that people with certain conditions—like hypermobility spectrum disorders (HSDs) [5], postural orthostatic tachycardia syndrome (POTS) [5], and mast cell activation syndrome (MCAS) [6]—often have gut symptoms too. We’re still not sure exactly why these gut problems are so common in these conditions.

This article looks at the role MCAS can play in these gut issues.

What is mast cell activation syndrome?

Mast cell activation syndrome (MCAS) is a rare condition where certain immune cells, called mast cells, become too active. These cells normally help protect your body, but in MCAS, they release their chemicals—like histamine—too often or for no clear reason. This can lead to a variety of symptoms, because the chemicals that usually help you can actually cause problems when there’s too much of them [7].

How common is MCAS in people with GI disorders?

Stomach and gut problems are very common in people with mast cell activation syndrome (MCAS)  [6].

One study found that these gut symptoms are often mistaken for other common tummy troubles, like irritable bowel syndrome (IBS) [6].  Out of 20 people with IBS who didn’t get better with usual treatments, 19 had symptoms that matched MCAS, and most tested positive for chemicals released by mast cells [6].  

Another study found that many people with MCAS get gut symptoms like feeling sick (nausea), vomiting (57%), or constipation (14%) [8].

How common is MCAS?

A study in Germany found that about 17 out of every 100 people may have MCAS [8]. In this group, most people (74%) said that family members, like parents or siblings, had similar symptoms too [9].

Mast cells and GI disorders

Mast cells are special immune cells found throughout the body, especially in areas like the gut. They help keep us healthy by fighting germs, helping wounds heal, and repairing tissues [7].

These cells can sense things like allergens, injury, or infection. When they are triggered, they release chemicals that help control the body’s immune response and blood flow [7], [10].

Sometimes, people with Mast Cell Activation Syndrome (MCAS) have more of these mast cells in their gut than normal. Normally, you’d expect about 13 mast cells in each small area of healthy gut tissue. However, in people with MCAS often have more than 20 [11]. This is seen mostly in parts of the small bowel, like the duodenum and ileum, and less in the stomach and colon.

Extra mast cells and their chemicals have been linked to gut problems like pain and sensitivity, especially in people with irritable bowel syndrome (IBS) [12], [13]. These chemicals may be one reason why people with MCAS have tummy pain.

MCAS and SIBO

Another issue is something called small intestinal bacterial overgrowth (SIBO). This happens when too many bacteria grow in the small intestine.

SIBO was found in about 31% of people with MCAS, compared to just 10% of people without it [14]. SIBO can cause symptoms like diarrhoea and bloating [15].

Experts think SIBO might happen in MCAS because the chemicals from mast cells affect gut motility or because of changes in the immune system. In turn, SIBO can make mast cells even more active, leading to more gut problems and inflammation  [6].

Mast cell activation syndrome and IBS

In people with irritable bowel syndrome or IBS, chemicals released by mast cells can lead to problems like constipation, diarrhoea, and pain. One study found that higher levels of these chemicals—like histamine and tryptase—in the gut were linked to more pain, especially when mast cells were close to nerves in the colon [16].

Constipation and MCAS

Constipation might happen when these chemicals are released near special support cells in the gut [17]. This can slow down how the large intestine moves, which may explain why some people with IBS get constipated.

IBS pain and MCAS

Researchers think that mast cells in the gut may be a key reason why people with irritable bowel syndrome (IBS) get tummy pain.

In one study, they found that chemicals released by mast cells in the gut of IBS patients made pain nerves much more active. The more mast cells there were, the more these nerves fired up and sent pain signals [18].

Two chemicals from mast cells—histamine and tryptase—were found near these nerves and seem to play a big part in causing pain. When these chemicals were blocked, the nerve activity decreased significantly [18]. This means that in IBS, mast cell chemicals can make pain nerves extra sensitive. This helps explain why people with IBS often have sore or painful tummies.

Summing up MCAS and gastrointestinal disorders

Mast Cell Activation Syndrome (MCAS) is a rare condition that can cause a wide range of gut symptoms, from pain and bloating to constipation and diarrhoea.

Because MCAS can look a lot like other gut disorders—especially IBS—it’s often missed or misdiagnosed. However, understanding the role of mast cells in the gut helps explain why these symptoms happen and why they can be so hard to treat with standard approaches.

If you or a loved one has ongoing gut symptoms that haven’t improved with usual treatments, it’s worth discussing MCAS with your healthcare provider. Or contact us for a FREE consultation. Getting the correct diagnosis can make a big difference to your quality of life.

Managing MCAS: Options and support

While MCAS can be challenging, there are ways to help manage symptoms. Mast cell stabilisers, such as ketotifen, work by calming down the mast cells and reducing the release of their chemicals. This can help ease tummy pain, bloating, and other symptoms.

Ketotifen and other mast cell stabilisers are available from Courier Pharmacy, where you can get advice and support from experienced pharmacists.

Remember, everyone’s experience with MCAS is different, and treatment should be tailored to your needs. If you think MCAS might be affecting you, speak to a healthcare professional for guidance or  contact Courier Pharmacy for a FREE consultation

This information is for general guidance only. For medical advice, please consult your doctor or healthcare provider.

References:

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