GP warns heartburn could be sign of a 'hidden' condition that affects one in six - if you don't get treated, it could kill

Daily Mail​

03-06-2025

An NHS GP has warned that millions of people in the UK could be unknowingly suffering a little-known condition that puts them at risk of a deadly allergic reaction.
Mast cell activation syndrome (MCAS) is an increasingly common blood cell problem that affects around one in six people, but is 'widely undiagnosed', according to Dr Asif Ahmed.
In a new clip posted to Dr Ahmed's Instagram page, where he has more than 100,000 followers, the medic said the symptoms, like heartburn, headaches and nausea, can easily be mistaken for other conditions.
'If you've got lots of symptoms, no one knows what's going on, you've been referred to one specialist then the other, then this is a condition you definitely need to consider,' he said in the video that has so far garnered over 40,700 views.
He added that the condition can cause 'almost any symptom including headaches, visual problems, nausea, heartburn, skin rashes, extreme fatigue or widespread joint pain', which is why MCAS often gets misdiagnosed.
Mast cells are a type of blood cell found all over the body, and are a vital part of the immune system.
These so-called 'police officer' cells detect different types of triggers and fight off infection.
'Firstly, mast cells are everywhere in the body—your eyes, gut, joints, skin—and when they release [the hormone] histamine you get symptoms,' Dr Ahmed explained.
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A post shared by Dr Asif Ahmed (MBBS, MRCGP, BSc) (@dra_says)
In a healthy person, mast cells trigger a protective response, but in someone with MCAS, they can mistake harmless substances such as pollen for infectious germs, and spark a range of unpleasant—and potentially dangerous—symptoms.
Other common triggers include alcohol, heat, medication such as antibiotics, insect bite and sings, exercise, certain foods, perfume and stress.
'In MCAS, what happens is that the mast cells inappropriately release histamine. This means a trigger, environmental generally, that normally shouldn't release histamine, does in you,' the GP explained.
This can cause a number of symptoms in different parts of the body—including the build-up of mucus in the airways, which become narrower, cutting off life-giving oxygen.
In some severe cases it can cause anaphylaxis, a severe allergic reaction that limits breathing and can be life-threatening.
As well as rapid organ failure, this can restrict oxygen to the brain, resulting in lethal brain damage.
Other common symptoms include swelling of the throat and tongue, difficulty swallowing, skin that feels cold to the touch, wheezing, and blue, grey or pale skin.
One telltale sign of the condition, present in over half of sufferers, is dermatographism—more commonly known as skin writing.
'This is when they can generally draw on their skin and this leaves a wide raised red rash,' Dr Ahmed explained.
Doctors can also run blood and urine tests to pick up high levels of chemicals released by mast cells during an episode—but this only works shortly after an episode.
Another way doctors may test for MCAS is by seeing if a potential sufferer responds to typical treatments.
Dr Ahmed said: 'Often patients who are thought to have MCAS just get started on treatment—which are generally H1 and H2 receptor antagonists and if there's a response to this, they're often diagnosed with MCAS.
'So generally it's a very easy and safe diagnosis option to take, and I think it's an option which is worth considering for people who have ongoing symptoms despite treatment and diagnosis for another condition.'
While there is no known cause of MCAS, according to the London Clinic of Nutrition, 74 per cent of people with MCAS have a first-degree relative who also suffers with the condition.
It has also been linked with obesity, irritable bowel syndrome (IBS), depression and type 2 diabetes.
In the most severe cases MCAS can cause severe reactions to almost everything, including foods.
This is the case for Caroline Cray Quinn, a healthcare recruiter from Boston, who can now only eat two foods—oats and a specially prepared nutritional formula.
Any other food could see her suffer a potentially fatal allergic reaction.
While Ms Quinn had severe food allergies growing up, she was only diagnosed with MACS in 2017.
'I got sick with MCAS in September of 2017 after one true allergic reaction to cross-contamination with nuts spiraled into a series of anaphylactic episodes to foods I wasn't allergic to,' Ms Quinn recalled.
'After a long waiting list of eight months, I saw an MCAS specialist who officially diagnosed me.'
She added: '(MCAS) presents in a lot of uncomfortable and life-threatening symptoms like difficulty breathing, swelling/itchiness in throat and mouth, loss of consciousness, low blood pressure, and hives/rashes.
'In order to avoid MCAS flare-ups and MCAS symptoms, I avoid triggers like food, animal fur/dander, mould, dust, heat, and certain smells.'