WOW, Summer 2026 has been a baptism of fire where Mast Cell Activation Syndrome (MCAS) is concerned! I thought I knew ‘enough’ about the condition having learned bits and bobs about it since my symptoms started 8 years ago. Boy, oh boy was I deluded! To be clear, prior to this summer I have had ‘mild’ reactions to sunlight (rashes on the tops of my feet), and occasionally facial flushing due to food. I followed the ‘medical’ low histamine diet for a short while a few years ago but symptoms were thankfully mild and short-lived, and I didn’t really understand what I was doing or why. I have had to learn more very quickly in the past 9 weeks as symptoms have been much more severe, more varied, and have completely wiped me out.
To give a bit of context, it is important to know where this flare sits within 2026. I had been actively trying to lose weight since September 2025, I signed up to a programme that didn’t encourage dieting but helped to change mindsets to bring about mindful eating. It worked for me and the food noise disappeared. I could eat whatever I wanted, I just didn’t feel the need to over-eat or snack. I lost a stone quickly (6 weeks) but then plateaued for 8 months. I figured my body just wasn’t ready to let go of any more weight and I would just wait it out. I did however lean towards a low carb diet as I had watched a nutritionist’s webinar in which they said low carb = more fat burning. ‘Couldn’t hurt’, I thought. So I swapped to low carb food in around April/May 2026. I got to eat my favourite things….regularly – bacon, eggs, meat in general and vegetables…lots and lots of vegetables (particularly salad – remember that). Again, I wasn’t sticking to any particular diet, I was simply cutting down on carbs.
At exactly the same time a few wider issues were going on; the UK was going through repetitive heatwaves, these brought M.E health challenges along for the ride and I struggled to function for the whole of the summer. I also developed heat exhaustion in June, I was drinking plenty of fluids but had run out of electrolytes temporarily (I now can’t take these either because they are full of MCAS unfriendly additives! I make homemade electrolyte drinks). Big mistake…huge! I had been going through peri-menopause for at least 2 years, had tried HRT but didn’t get on with the faffiness of applying gel (my M.E brain didn’t like the faff and specific instructions). My GP wouldn’t allow me to use patches. So, I returned to using herbal supplements instead, as they had worked to take the edge off previously. In my mind, I was dealing with perimenopause and it wasn’t an issue (I return to this later on). Lastly, I had had 18 months of chronic stress, not work-related, that I had been managing privately – to my Sensate machine….thank you!
This context is important, as it helps to understand why I didn’t have a blooming clue what the trigger behind this flare is. Personally, I believe it was a perfect storm of all of the above. All of the factors named above are known triggers for MCAS flares. I had been coping with all of that for months before my body just said ‘STOP’ very loudly. I take antihistamines every day, and have done for years due to minor allergy stuff. I believe that is why I didn’t get any visible early signs of worsening MCAS.
This flare started quickly and dramatically with 6 days of diarrhea, followed by a week of constipation. This cycle has been repeated throughout the 9 week flare, irrespective of what I have eaten (food info coming up). Pain in my Duodenum started in week two alongside ‘tickling’ sensations on the skin covering my Duodenum – known ‘symptoms’ of MCAS. I have had the same sharp pains in my Duodenum at least a few days a week since then. It has been explained to me that the inside of my Duodenum currently has the appearance of bad sunburn because of the impact of the MCAS flare on my insides. This means it is very sensitive, and nerve endings are ‘irritated’. I mentioned the MCAs flare to my GP during an appointment about another issue and she prescribed Famotidine to help with digestive issues. Famotidine works for me (reduces some symptoms) so you can imagine how annoyed I was to learn it would not be re-prescribed without a GP F2F review and the next appointment couldn’t be even booked in until 3 weeks later. For an illness that I have been told can’t be diagnosed locally by the NHS. Great!
A few days into this flare is when the ‘allergic’ feeling began all over my body. I am acutely aware of this feeling on my face and neck but it is present in a lot of different places. In fact, anyone who has watched any of my recent videos will see I now scratch my face, usually my chin, regularly. This is because my skin is tingling or itchy. Think hayfever on steroids. My eyes are scratchy/watery/dry/sensitive most of the time, sinuses are irritated – I sneeze a lot and not solely due to pollen. I am reacting to EVERYTHING and anything – this is new for me. I have had pollen allergies for years, this is partly why I take antihistamines every day. Now I react to more chemicals, odours, environments than ever before. To the point that I can’t pre-empt encountering any difficulties.
I didn’t know histamines (and subsequently MCAS) were in every part of a human body, including connective tissues. Week 3 is when my wrists first became additionally painful and when my knees felt at even greater risk of subluxing.
Week 5 is when MCAS started wanting to play with my Dysautonomia. My broken/badly sprained foot is still healing and I am having to spend a lot of time flat with my feet elevated above heart level to help the healing process. This may be why my lightheadedness and inability to stand for longer than 30 seconds was more noticeable.
In week 7, my throat and chest felt the full impact of MCAS. My throat partially closed over. I don’t know if ‘partially’ means the term anaphylaxis can be used. But I was genuinely frightened because I was having breathing difficulties due to an allergic reaction – I still don’t know the specific trigger. My lips were tingling but there was no visible sign of MCAS on my face during this episode – no rash, hives, or swollen lips etc. My throat was sore and narrowing and my chest HURT. Breathing HURT and my chest felt very tight. I do not have access to Epi-pens (or equivalent) so I took an additional antihistamine as that was all I had available and waited to see if it would worsen and I would be in need of an ambulance. I rested on my bed and waited. The antihistamine was enough (I’m guessing), the narrowing stopped after about half an hour. It took 24 hours for all of that reaction to stop. During that 24 hours I contacted my GP via e-consult to ask if I could be considered for an epi-pen, I explained what had just happened. I was triaged and sent a message advising me that they would be in touch in 2-3 weeks to arrange a telephone appointment with my GP. O….K. Not loving the lack of urgency but, as I can’t afford to buy one privately I had/have no choice but to just wait. Readers in the UK will appreciate that if my family have to phone 999 due to a future allergic reaction, they will do so with the knowledge that the ambulance may not arrive WiTH AN EPI-PEN in time. It is a very real concern. This is why I want to have access to an epi-pen in my own home.
I have always been aware that MCAS can be triggered by more than food. But it is the only thing I am able to control. I can control what food and drink I put into my body. The research I have done over the past 9 weeks has told me the low histamine diet is just one tool to combat MCAS flares. I have been eating low histamine foods for about 8 and a half weeks now. It’s been a slog. Low histamine food isn’t grab and go if I’m having a low energy day or going through PEM. It has to be cooked from scratch after being stored correctly (batch cooking can be done but it has to go straight in the freezer). Foods cannot be stored in the fridge as this causes histamines to increase. Remember, in the context above I mentioned heatwaves and eating vegetables, particularly salads? We had resorted to putting all of our fresh foods in the fridge to prevent them going ‘off’ quickly in the heat. I now know that was simply causing histamine levels to increase IN ADDITION to most of those vegetables being high in histamines to begin with. I believe, where food was concerned, it was an accumulative effect that reached a tipping point 9 weeks ago. I don’t want to be on such a restricted diet for any longer than necessary so once a fortnightI ‘test’ my MCAS. I eat something that I have had a mild reaction to in the past 9 weeks to see if the sensitivity continues. So far, my sensitivities continue. I get facial flushing, a burnt mouth feeling, I feel ‘allergic’, and have itchy skin.
To give you an idea of the types of things I am eating at the moment I am going to give some examples here. But, everyone with MCAS is different – I can tolerate these foods, others may not be able to – and vice versa. Please don’t suggest recipes etc in comments- thanks.
Breakfast –
Gluten-free Porridge made with water with a handful of frozen Blueberries.
Scrambled eggs made with water, salt/pepper.
Homemade Hash Browns (potato, extra virgin olive oil, salt/pepper) with an egg on top (fried only in EV olive oil)
Lunch –
Rice cakes with boiled/mashed carrots, drizzled with EV olive oil.
Gluten-free pasta, with butternut squash or carrots, drizzled with EV olive oil
Dinner –
Rice or GF pasta, frozen chicken (airfried from frozen), courgette, carrot, butternut squash, drizzled with EV olive oil.
Jacket potato/mashed sweet potato, chicken (airfried from frozen), courgette, carrot, butternut squash.
Snacks-
Pumpkin seeds
Lightly salted rice cakes
Apple (skin peeled off)
The only oil I can tolerate is Extra Virgin Olive Oil, in the first few weeks I found I wasn’t eating enough calories every day so resorted to putting EV olive oil on most meals to artificially bump up calorific content.
Newbies to MCAS, there are numerous MCAS support groups on social media, including some that concentrate on food and recipes. I have found these groups to be invaluable in the past 9 weeks! In particular, @Drasayspodcast (YouTube channel). He’s a UK GP who posts regularly about a range of chronic illnesses. His MCAS content has been helpful, to me personally.
Dr Google and MCAS charity websites told me that there is plenty of anecdotal evidence that hormones can play havoc with MCAS. I noticed that the week before my period and during ovulation, my MCAS symptoms worsened even further, irrespective of my environment or what I was eating. Dr Google assured me this was ‘normal’ and experienced by many people with MCAS. I spoke to a friend with MCAS (and M.E.) about my flare and she told me the worst flare she had been through had been after she had gone onto a low carb diet whilst going through peri-menopause without HRT. It is this conversation that made me realise the context behind my flare and why I realised it was a perfect storm (not just one thing). Thanks to that conversation I started to understand how my hormones are interacting with MCAS and that I needed to try HRT again to stabilise my hormones so the MCAS would be less like a rollercoaster! I also stopped taking the menopause supplements as I realised they contained extras (bulking agents etc) that caused my body to release histamines. I contacted my GP to arrange an appointment, was again told I would be contacted to arrange an appointment in 3 weeks’ time. In week 9, my hormones are running wild, untethered and I have no prescription medication to reduce MCAS reactions or to take if I have another nasty allergic reaction, because I am waiting to talk to a GP about an illness many GPs don’t believe in and have no referral to offer me. The joy I feel about this is just……! It’s my M.E. ‘journey’ or 2006-2009 all over again! Yippee!
I have come across the term ‘Histamine bucket’ since this flare started and I think it’s a useful way to think about how MCAS and Histamine intolerance works. I’m going to include it here as it might help people new to MCAS or histamine intolerance. The charity Mast Cell Action has a very good explainer page on their website – https://www.mastcellaction.org/the-histamine-bucket-theory I’ll summarise this theory below –
Imagine your body has a bucket. Throughout the day, different things add histamine to that bucket, like certain foods, stress, exercise, allergies, infections, hormones, or even changes in the weather. Normally, your body is constantly emptying the bucket using enzymes that break down histamine, but if you’re producing more histamine than your body can clear, the bucket starts to fill up.
The problem happens when the bucket overflows. That’s when symptoms can suddenly appear, such as headaches, itching, hives, flushing, digestive issues, brain fog, anxiety, dizziness, or a racing heart. Often, it’s not one specific food or trigger causing the issue, instead, it’s the combined effect of multiple histamine sources building up over time.
This theory also helps explain why someone might tolerate a food one day but react to it the next. If their bucket is relatively empty, they may have no symptoms. But if stress, pollen, poor sleep, hormonal changes, or other high-histamine foods have already filled the bucket, that same food could be enough to push them over the edge.
While the histamine bucket is a helpful visual model rather than a formal medical diagnosis, many people with histamine-related symptoms find it useful for understanding why their reactions can seem unpredictable and why managing overall histamine load, rather than focusing on a single trigger, can make a difference.
Reader, my bucket runneth over 9 weeks ago….and continues to do so!
When this episode began, I anticipated that this flare would be short-lived and only be a little bit inconvenient for a few weeks. Unless going onto HRT is a miracle cure, I can see this is going to last for a while yet, despite my best efforts. But, I know to not get stressed about it as that will just make it worse.
I turn 50 in a few weeks. A 50th birthday without cake……. eek!!!
Love
Sally
and Foggy (OBVIOUSLY) xx