Perimenopause, Menopause and MCAS-Connection
Written by Keris Marsden, BANT registered nutritionist and MCAS sufferer of 7 years
I’ve been asked these questions many times over:
Does perimenopause trigger MCAS?
Does menopause worsen MCAS Symptoms?
Is it the symptom hormones or MCAS?
I’ve had first hand experience investigating this too.
My MCAS kicked off in my late thirties and coincided with hormonal issues that led to a diagnosis of “likely early menopause” at first. I headed off on a journey of HRT and other menopause support only to find the answer didn’t really lie there.
I’ve detailed some of my story here.
The MCAS - Hormone Link
Before I discuss links between MCAS and hormones I want to make it clear that the situation is always more complex than a life stage, hormone level changing or anything else you’ve led to believe.
As humans we often like to find one thing, one explanation but you know yourself better than anyone.
And you definitely know there’s never one thing changing in your life, it’s the same within your body.
What actually links hormones, menopause and MCAS is what scientists call Psychoneuroimmunology (PNI)
The study of bidirectional communication between the central nervous system, endocrine system and immune system.
This is why it’s imperative to understand how your thoughts, emotions, behaviours and stress influence your immune function and physical health.
Remember:
Your mental states can directly influence your disease risk and the progression of many chronic diseases.
What’s Helpful To Know
In your forties your cycle may become slightly irregular which can change the ratios of estrogen and progesterone.
Many women experience digestive issues, sleep disruption, increased anxiety, histamine intolerance (increased allergies, skin itching and flushing) and mood alterations
Some clients I work with say they feel like everything appears to have gone wrong all at once.
If this sounds familiar, there's something helpful to know.
Perimenopause and Mast Cell Activation Syndrome (MCAS) are more connected than most practitioners, including many GPs, realise. Understanding this connection could be the missing piece you've been searching for.
What is Mast Cell Activation Syndrome?
Mast cells are immune cells found in virtually every tissue of the body.
Their job is to defend you. They respond to threats like allergens, infections and environmental stimuli by releasing inflammatory chemicals, the most well know is histamine but that’s not always the most problematic.
In MCAS, mast cells are chronically overactivated.
They fire when they shouldn't, releasing a cascade of chemicals that produce a bewildering range of symptoms across multiple body systems.
Common MCAS symptoms include:
Gut issues (bloating, nausea, reflux, diarrhoea)
Skin reactions (flushing, hives, itching)
Neurological symptoms (brain fog, anxiety, headaches)
Fatigue (sometimes post meal)
Food intolerances
Joint pain, headaches
Cardiovascular issues: tachycardia, low/high blood pressure, bruising, nose bleeds and bleeding gums
The diversity of symptoms is precisely why MCAS is so frequently misdiagnosed or missed altogether.
I now help many people manoeuvre through an MCAS diagnosis and the implementation of nutrition and lifestyle support including working with trusted medical professionals who prescribe MCAS medication and/or hormone replacement therapy.
If you'd like to find out more about working together, you can book a free 20-minute discovery call.
Estrogen And Mast Cells
Here is where the perimenopause and menopause link becomes helpful.
Estrogen and mast cells have an inter connected relationship.
Mast cells carry oestrogen receptors so they can respond to circulating oestrogen.
When estrogen rises mast cells can become significantly more reactive.
Progesterone, on the other hand, generally has a stabilising effect on mast cells.
As progesterone begins to decline earlier in the perimenopause transition than oestrogen, the body loses a natural buffer against mast cell overactivation.
The result?
Many women who have had manageable or subclinical MCAS for years suddenly find their symptoms escalating dramatically in their late thirties and forties.
Foods they've eaten without issue for decades become triggers.
Histamine intolerance and allergies worsen.
Gut symptoms become unpredictable and more widespread.
Anxiety, brain fog and distracted thinking become more debilitating.
At this point women are often told it's simply 'just hormones' without any deeper investigation into links with their immune system.
If you’re already exhausted and overwhelmed by this situation you can book a consult with me and get started straight away with a personalised, integrated treatment plan designed specifically for you.
Does Perimenopause Trigger MCAS, Or Reveal It?
This is a distinction worth making.
MCAS is thought to have genetic, environmental and emotional roots, and many women have had it (at a lower, manageable level) for much of their adult lives.
My own health issues began in puberty with heavy menstrual cycles, anaemia, dermatitis, acne, IBS, PCOS, infertility and looking back many could be linked to MCAS.
What perimenopause does is destabilise the hormonal environment that may have been keeping mast cell reactivity in check.
This is why the perimenopause years are often the point when women finally receive an MCAS diagnosis.
The Long Covid and CIRS overlap
It's also worth noting that MCAS is increasingly recognised as a driver of symptoms in Long Covid and Chronic Inflammatory Response Syndrome (CIRS).
These two conditions share significant overlap with each other and with perimenopause in terms of fatigue, brain fog, immune dysregulation and nervous system symptoms.
If you have Long Covid or CIRS alongside perimenopausal symptoms, the chances that mast cell activation is playing a central role in your experience are high.
What can you do about it?
The good news is that MCAS, and its intersection with perimenopause, is something that nutritional and lifestyle intervention can genuinely support.
The key is addressing the system as a whole, not just individual symptoms in isolation.
From a nutrition perspective, this means:
Supporting histamine metabolism with targeted nutrients (DAO enzyme, vitamin C, B6, copper, luteolin, quercetin)
Reducing the overall inflammatory load through anti-inflammatory eating, tailored to your specific triggers
Supporting gut health and intestinal permeability, which plays a major role in immune reactivity
Balancing blood sugar, which has a direct effect on mast cell stability
Considering the role of hormonal support — including whether HRT might be appropriate for your situation — as stabilising oestrogen can reduce the volatility that is driving mast cell overactivation
From a nervous system perspective:
Chronic stress is one of the most powerful triggers of mast cell activation.
This is why I help clients begin a journey of personalised nervous system regulation and this is central to recovery.
Together we collate a toolbox of practices including somatic enquiry, mindful movement, deep rest, and addressing the emotional weight of living with a complex chronic condition.
Many women with MCAS have been running in a state of high alert for years. Nutritional intervention alone will not resolve this and so a truly integrated approach is essential.
When to seek specialist support
If you recognise yourself in this article and your symptoms have escalated during perimenopause, if you've been struggling with unexplained multi-system reactions, or if you suspect MCAS is part of your picture — it's worth seeking support from a practitioner who understands both MCAS and hormonal health.
FAQ’s: Perimenopause and MCAS
Can perimenopause trigger MCAS?
Perimenopause is unlikely to cause MCAS from scratch, but it is one of the most common triggers for existing MCAS to escalate dramatically. Many women have had subclinical or manageable mast cell reactivity for years without realising it. As progesterone begins to decline in perimenopause, often before oestrogen does, the body loses a natural buffer against mast cell overactivation. So rather than triggering MCAS, perimenopause tends to reveal it.
What are the symptoms of MCAS in women over 40?
MCAS symptoms are wide-ranging and often mistaken for perimenopausal symptoms alone, which is why the condition is so frequently missed. In women over 40, common MCAS symptoms include unpredictable food intolerances and reactions, flushing, hives or skin itching, bloating, nausea, reflux and gut issues, brain fog, anxiety and difficulty concentrating, joint pain, fatigue — particularly after meals — heart palpitations, tachycardia, and recurrent headaches. The key distinguishing feature of MCAS is that symptoms tend to affect multiple body systems simultaneously and fluctuate in ways that don't respond predictably to standard treatments.
How do I know if my symptoms are perimenopause or MCAS?
This is one of the most common questions I'm asked and the honest answer is that it is often both. The symptoms overlap significantly: flushing, sleep disruption, anxiety, gut issues, brain fog and mood changes are common to both conditions. If your symptoms are highly variable, triggered by foods, smells, stress or environmental factors, affect multiple body systems at once, and haven't responded well to standard HRT or perimenopausal support, MCAS may be playing a central role. A practitioner who understands both can help you unpick this.
Can HRT help with MCAS symptoms during perimenopause?
For some women, stabilising oestrogen can reduce the hormonal swings that driving mast cell reactivity. But, and this is important, some forms of HRT, particularly synthetic progestogens, can make MCAS symptoms worse. I personally suffered with progesterone intolerance that worsened all MCAS symptoms. Introducing HRT carefully and monitoring your full symptom response is really important if MCAS is present.
What foods should I avoid with MCAS during perimenopause?
There is no universal MCAS diet, and this is important to understand. Mast cell triggers are highly individual. During perimenopause, when mast cell reactivity is heightened, even foods previously tolerated well may begin causing reactions. Rather than following a blanket elimination diet, working with a registered nutritionist to identify your specific triggers is far more effective and sustainable.
Can a nutritionist help with MCAS?
Yes. A nutritionist specialising in MCAS can help you identify your individual dietary triggers but also stabilise the terrain to tolerate more foods. Reducing the overall inflammatory load and nervous system stress on your system is also paramount to improve gut health, intestinal permeability, and balance blood sugars.
How long does it take to see improvement with MCAS?
This varies significantly depending on how long MCAS has been active, the complexity of your symptom picture, and how many contributing factors are involved. Some clients notice significant improvements within 4 to 6 weeks of targeted nutritional and nervous system support. For others with more complex or long-standing presentations, significant improvement may take several months. What tends to make the biggest difference early on is reducing the overall load on the immune system rather than trying to address every symptom individually.
Is MCAS a recognised condition in the UK?
MCAS is increasingly recognised within the medical community, though awareness among GPs remains inconsistent. Diagnosis can be challenging because standard allergy tests and blood panels often come back normal, and symptoms span multiple specialities. Many people with MCAS spend years seeing various specialists before receiving a diagnosis. If you suspect MCAS, seeking support from a practitioner with specific expertise in the condition, whether a nutritionist, immunologist or specialist GP, is often the most effective route forward.
How I can help
I’m a registered nutritionist who specialises in helping people with MCAS, CIRS, Long Covid, and the hormonal transitions of perimenopause and menopause.
After a 7 year battle with chronic illness myself and the joy of being a ‘medical mystery’ to many expert consultants I finally received a diagnosis of MCAS through my own investigations.
I now help many people with complex health conditions implement integrated healthcare with personalised nutrition, nervous system support and supplements. I also have a number of trusted medical professionals I refer to where needed for support with MCAS medication, gastroenterological investigation, allergies and hormone replacement therapy.
If you'd like to find out more about working together, you can book a free 20-minute discovery call.
