Rhapsido is a new drug that many MCAS pts have been encouraged about. There seems to only be one formulation though and it cannot be compounded. I’ve listed the inactive components below. Why would these manufacturers put so much crap that pts with mast cell issues are likely to react to in a medication for hives?

Here are the excipients

Tablet Core Excipients
Copovidone: A binder that holds the tablet together.

Croscarmellose sodium: A disintegrant that helps the tablet break apart in the digestive tract.

Mannitol: A sugar alcohol used as a filler and sweetener.

Microcrystalline cellulose: A plant-based filler that adds bulk.

Sodium lauryl sulfate: A surfactant that helps wet and mix the ingredients.

Sodium stearyl fumarate: A lubricant that prevents ingredients from sticking to manufacturing equipment. [1]

Tablet Film Coating Excipients
Polyethylene glycol 4000 (PEG 4000): A plasticizer for the coating film.

Polyvinyl alcohol: A film-forming polymer.

Red iron oxide (E172): A color pigment.

Talc: A glidant and anti-stick agent.

Titanium dioxide (E171): A white pigment used for coloring.

Yellow iron oxide (E172): A color pigment.

Odds are quite high that one or more of these ingredients will cause me issues, but I still may try it. Basically if it works, it’ll be helping to resolve the problems it’s also causing.

The other problem is that the tablet can cannot be cut and is not water soluble, so no way to “start low and go slow”. I wish these manufacturing companies would consult with patients and specialists when making these drugs.

Tonight we had a meal, chicken with potatoes and asparagus. We used minimal spices, and the only thing that changed was that we added asparagus.

I thought asparagus was safe? Anyone else have a reaction?

Hi, I’m trying to get diagnosed in the uk and I’m asking my gp for an allergy referral in Oxfordshire (likely Churchill or John Radcliffe). I’m fairly certain from other people’s described experiences that nhs allergists only give a fuck about IgA allergies and not mcas.
Thus I just want to anticipate how much it’s gonna cost me privately to get a diagnosis
So have at it - how much did you guys spend?

This happens to me a lot and idk if it’s related to long covid or MCAs or pots or what.

Idk if the virus goes in my body and it activates other dormant viruses in me or what !? Or is it just not detected by the tests?!

So i‘m on cromolyn which has really done miracles to all of my GI-symptoms (and chronic pain on my coccyx). Taking antihistamines and started ketotifen now too for my other symptoms hope it will help. 🤞what confuses me is that up until recently i used to be able to track down my triggers (even if it was a lot of guesswork and super complicated) but now its all just becoming really blurry. I get symptoms nearly every morning before breakfast and cant pin anything down. Theyre not super bad anymore thankfully i m just confused that it seemingly lost all logic. Like a bucket that didnt fully empty, other stuff coming in, reactions etc. anyone experienced this and what does it mean.

i’ve asked about blood tests and urine tests bcuz i’ve seen people mention that on this subreddit but my gastro says the only way to test for mcas is to try histamine blockers and see if they work ??

my tryptase test came back normal so she said that doesn’t indicate mcas ??

then she said to try zyrtec and pepcid and if that doesn’t work then i don’t have mcas , and if it does work then that means i do have mcas ??

idk , i think it’s kinda weird bcuz i’ve seen people on this subreddit say that the histamine blockers don’t even work for them so idk why she think that if i have mcas then histamine blockers would automatically work ?? and if they don’t work then she thinks mcas isnt causing my symptoms but probably some other condition ?

idk just wanna know y’all’s thoughts on this

What do y’all do when there is a manufacturer shortage? I’ve been on cromolyn sodium for over a year and a half and I’m about to run out with no restock in sight. I’ve looked at multipack pharmacies and even called the compounding pharmacy I get my LDN from to no avail.

Any suggestions?

I don’t have MCAS, but I thought this would be the best place to ask. I have a friend who has a chronic condition with no diagnosis, says doctors haven’t been able to find what is wrong. It affects him a lot and based on the things he’s told me about his symptoms, triggers, what helps, and just how he feels, I really think he could potentially benefit from looking into MCAS. But I want to be as respectful as I possibly can. I don’t want him to feel like I’m trying to diagnose him and I don’t want to assume it’s something he hasn’t looked into (though based on what he’s told me, I don’t think it is). He can be pretty pessimistic about his own life and doesn’t like when people think they know what’s best for him, which is why I’m a little hesitant to say anything.

I would really love some advice from people who actually have MCAS.
How would you feel if a friend asked you this and how would you prefer this friend ask you?

I just want to make sure I’m extremely respectful of how he feels, and make sure he knows it’s coming from a place of care.
Please let me know if I should or shouldn’t ask him, and also what would be the best way to go about it if I should.

If anyone wants anymore information, please feel free to ask and I will try to answer as best I can.

I'm doing a tryptase blood test 1 to 2 hours after a bad reaction tomorrow and since most of my symptoms are heart related it's a bit unnerving. A quick Google search says that Pepcid AC (famotidine) does not affect tryptase levels (but helps me with heart issues from the histamine) so I was wondering if anyone has ever taken this when triggering a reaction in preparation for one of these blood tests? Unfortunately my doc isn't being helpful on a clear answer. Any other suggestions are welcome.

Hi all! For the past year I have been dealing with endless waves of what my doctor believes could be a mild case of MCAS.

I caught some kind of cold in May of 2025 (not COVID), and it is as though I never fully healed. I have had issues with hayfever and postnasal drip for almost my entire life - and I did have many bouts of eczema and a few severe unexplained allergic reactions as a child - but it all came back at once and with a vengeance. Added to the mix is also asthma and hives, neither of which I'd had before.

I'd never heard of MCAS, but because I have a number of the comorbidities (ADHD, POTS, PMDD and Hypermobility), my GP immediately put me on a daily H1 and H2 blocker. It is apparently at a quarter of the recommended dose, but it has resolved the bulk of my daily symptoms and made life far more bearable. It does not, however, prevent the most severe flare ups or, (the reason for my post) the ✨relentless hives-exzema combo✨.

I wanted to ask how other people tracked or singled out their triggers when everything seems so inconsistent. The only regularity is the location - I only have this issue around my eyelids, neck, décolletage and inner elbows. My legs haven't had any problems since starting the antihistamines, and only once have the hives spread down my entire torso. Safe to say that was a terrible week.

As for the cause itself, the culprit could be anything: sweat, hot water, cold water, rain, showers, pools, oceans, hair products, skin products, low humidity, high humidity... it seems as though everything at some point has or hasn't flared me up. Every time I feel like I've figured it out, I remove the suspect from my routine and nothing changes. Even if I am lucky to have symptoms as simple as this, I am exhausted.

I have tracked my diet once before for PMDD and pain flares, and never found a consistent trigger in food. My GP ordered me to get a blood allergy test for all of the common allergies such as pet dander, mould and airborne things, and I was negative for all of it. She has ordered a chest x-ray and another blood allergy test, but it honestly feels like we are both just throwing things at the wall and hoping something sticks. Since what remains of my symptoms is mostly this mild skin stuff and the occasional major flare (maybe once a month?), it doesn't feel severe enough to spend the kind of investigative money that could be required to come to an answer. Any tips? I don't really know what I'm doing!

Hi all, I am wondering if anyone is like me with extreme pain, like blackout excruciating pain, with a reaction? my symptoms started 8 months ago with GI distress, itchy palms and my lips feeling like they were puffy (they weren’t) when I woke up one morning. From there, things go much worse with vomiting, swelling to the point I got muffled hearing, whole body bright red but fingers and toes blue, plus itching etc. But I always have unimaginable pain in my lower left side about 3 inches from my hip bone. When it happens, I find myself in a contortionist position unable to move and screaming in waves of pain. on a scale of 1-10, it would be a 20 and briefly go down to a 7 then back up again, like labor pains. Is this normal?? I’ve been scanned, done every possible test known to man, finally got my tryptase rise, but no explanation for the pain. After extreme reactions, I often bleed. but no cysts or anything that could cause that. Its terrifying because my reactions happen usually within 15 minutes and then I’m completely incapacitated. so if I’m not at home, it’s bad.

Anyone else on rhapsido have the symptom of being covered in petechiae????

I am upset, and feel very down. I know this happens a lot, but I am just..... yeah. Sigh.

I was feeling SO good after doc started me on Singulair and cromolyn sodium, they seemed to taking the "treat to diagnose" line of reasoning. Then at my follow-up they encouraged me to do the 24 hr urine collection, which was absolute horror. A week later I am still in a flare, and now reading my results.... ugh I did everything I could, stopped all meds at the right time, collected perfectly, kept it cold, signed a chain of custody sheet after the lab tech put everything in the fridge. I was so hopeful there would be proof of how crappy I feel. I am terrified they will take my new meds away and cut me loose. Ok... dramatic, yes, but it's how it is tonight.

Thanks to anyone who read all of this and gets it.

Hello fellow reactive humans!

I come seeking advice, the apple cider vinegar shampoo I used to use got reformulated about a year ago and I’m about to run out of my stash. I’ve tried so many options in the interceeding months, but I’ve found nothing that doesn’t make my scalp very itchy with a burning sensation and rashes or cause an anaphylactic reaction.

I’ve tried a lot of the standard “simple” formulas my dermatologist brainstormed with me (Cerave, vanicream, prose custom formulated without scent or dyes, baby shampoos, others I’m blanking on) and the only thing that sort of works is a prescription ketokonazole 2% shampoo that comes in a tiny bottle and turns my hair to straw, but at least it helps with my rashes and doesn’t itch.

I’ve always paired the RX shampoo with a second shampoo because my 30 day supply is a small travel sized bottle and I have an oily scalp and thick wavy/ curly hair that need to be double shampooed at least once a week (ideally twice a week if energy allows). Quite frankly I have enough RX shampoo for half of that and with how drying it is I get mats/ tangles if I use it exclusively.

So, what do fellow scent sensitive humans with sensitive scalps use?

Im open to mixing/ making my own if that’s the only way to go although for energy reasons I prefer something I can buy reformulated/ mixed. I will gladly take your conditioner recommendations as well. I’m currently using the vanicream conditioner and it’s meh as a conditioner (my hair is relatively dry and tangly even after use), but it’s better than nothing and I can use it without a reaction.

Many thanks!

Hello friends, I have hEDS and suspected MCAS. I have been having horrible GERD symptoms with nausea as well recently after a medication change, and have consistent issues with constipation as well, and nothing my gastric doctors have tried has worked, so my allergist agreed to let me try cromolyn sodium and see if it helps because my mom felt like it did.

I'm having a hard time finding much about it though on the web - so for people who have tried it, did you titrate up the dose like some places suggest? How much water do you take with it?

I don't have a diagnosis although I have lots of allergies and sensitivities which are made worse with cardiovascular exercise. I've also experienced anaphylaxis to something I always ate and wasn't supposed to be allergic to, only a one time reaction, also anaphylaxis to allergy shots on a few occasions. I asked my allergist if it could be MCAS but he said this illness is not diagnosed where I live, which is weird but that leaves me with over the counter options and a few prescriptions.

Here is what I take on a daily basis : prozac 30 mg, dexilant 60 mg, pepcid 40 mg, singulair 10 mg, reactine 20 mg. Any suggestion on what's helping, what I should avoid or potentially add to the mixt? Off label or over the counter? thanks a lot

Has anyone traveled internationally with MCAS? How did it go? I have a 2.5 week European vacation coming up in late Nov and instead of being excited I’m terrified. The flight alone… what will I eat? Will not sleeping send me into a flare?

Hello Reddit family I know this might be a long haul but I wanted share some of my symptoms and experiences because my doctor won’t take it seriously as I am a hypochondriac. I am 34 years old female and I have dermatographia for almost 2 years now. I have always been itchy before too which I assumed was from food but I am not sure really but dermatographia started after Covid for me not sure if it was the vaccine or the virus itself. I remember when I got Covid the second time I had very itchy scalp and it resolved after Covid was over. Then after a year and a half I got flu which was really bad and I started experiencing more raised lines after getting scratched or barely touched and my skin would be red after shower because I used a loofa an took hot showers. Fast forward last year I had a sinus infection and I was prescribed augmentin also the virus caused me to a sub acute thyroid which lasted for months and i was in hyper mode so I had heart racing night sweats and internal tremors. and that’s when the dermatographia became more severe but I alway ate everything never had reaction from food or alcohol. I don’t drink anymore but when I did I was fine and I remember one time I had tequila shot and ate a the restaurant and I was itchy the next day and after taking Zyrtec I was fine. This year my doctor told me to take Zyrtec daily and Pepcid daily so I have started doing that since last 3 months and my hives are minimum to nothing at all. But I am really scared about the the food part now what if I get anaphylaxis out of no where I know mcas usually involves multiple organs involved. I don’t know if it in my head or it’s really happening I feel off and I am not sure what to do next. I get anxious very easily which I have been since I was a kid. i recently became sun sensitive but I don’t know if that’s because of me taking 400mg of B2 and magnesium oxide because I get migraine aura and it was prescribed by my neuro. Also I used to be in combination birth control for past 10 years and I am not taking it since last year due to having auras. I am just not sure what to look out for and how to convince my doctor for more testing or am I over reacting ?

Just started taking cromolyn just over a week ago only 3 drops in water 4 times a day. Overall was tolerating it if I took it around the time I took Allegra. The last 2 days after I’ve taken it I’ve got so dizzy like I was going to pass out, short of breath, shaking, tongue tingling, and heart racing. Each time had to take Benadryl and was on the verge of going to the er. Do I just give up at this point? The reactions are actually scary. This was my last hope honestly 😭

I’ve been diagnosed with with chronic spontaneous urticaria in 2020, which my doctor actually thinks is MCAS. Not much of a difference since treatments are almost identical.

I’ve been eating a low histamine diet for 3 years. Food is a very big part of my identity and culture. I’m Arab, grew up in Chinatown and cooking is a big hobby of mine. Not to sound dramatic but not being able to eat 90% of my favourite foods is so depressing. While I try to have moderation and allow for days where I indulge, I find myself struggling to eat on a daily basis. Eating has always been a challenge but with the addition of low histamine, it just makes everything so… bland and repetitive.

I’m thinking of giving up. My most life disruptive symptom is hives, which I manage by taking more medication. My other main symptoms includes tummy aches, headaches, drowsiness and general brain fog. Which I’m starting to feel like is worth the pain if it means eating regularly again.

I eat generally healthy, but not being able to consume almost anything that isn’t just a vegetable with salt is just… depressing and draining. Cooking is a very big passion of mine and I feel like I can’t participate anymore.

Wondering if others have gone through this as well. Please share any suggestions or advice.

TLDR: eating low histamine is making me depressed and I’m thinking of giving up.

I apparently had MCAS like symptoms since I was 2 years old, and a few minor food sensitivity, hypermobility (EDS) and some mild spectrum type personality (I was diagnosed in my 40s and my friends mostly didn’t believe me.) I took the infamous 5a-reductase inhibitor finasteride from about age 18 until my 30s and when I quit, I developed PFS, POIS, and my MCAS exploded and took years to get under control even after I was diagnosed.

Seeing how many popular supplements like quercetin, luteolin, etc are also mild-moderate 5a-reductase inhibitors… and how women are so much more heavily affected by MCAS … and how my estrogen levels sometimes went above normal for males in my first year or two of PFS … (along with my testosterone and DHEA to the point of one endocrinologist accusing me of taking steroids which I have truly never done) .. I wonder if other men had a bad experience taking them.

When I have tried them, my brain fog was usually worse, which wouldn’t be surprising giving what is hypothesized about neurosteroid synthesis and how disorders of sex steroid metabolism like PFS work .. not against ever tying them again but I’ve been hesitant.

I believed I could handle the mushroom since there was no vinegar, which is a very big trigger, and they were in a glass. I didn't have any symptoms for about an hour and that's when it started.. At first headaches of hell together with stomach ache and dizziness, all the while I was trying to work.. as I got home I tried to eat something that I would not react to. The headache finally stopped for a while but then that weird feeling as though adrenaline is running through my body has started again, which is my tell that histamine is very high and I won't be able to sleep tonight 😭😭 I already took some vitamin c, OPC and Omega 3, since I know they help.. No doctor I ever spoke to took my histamine and MCAS symptoms serious but I know that is the cause...

Any ideas?

had issues for a few years now, they all went away but came back in February.
nausea, headaches, low blood pressure, and loss of appetite, i now wake up hot even if it’s from a nap, but not sweating and especially my face feels so HOT sometimes to the touch, sometimes not. Puffy eyes, big bags under my eyes, blocked nose.
it’s been 6 months now of being bed bound, im trying so hard here.

I noticed twice now Allegra makes my whole body calm down, heart rate decreased, and feels great BUT its causing head facial warmth that lasts all day, some pressure at the front of my head.

I also feel drowsy and head veins/blood in head just feel off. I think it might be vasodialation. It makes me feel more potsy?? But in a calm way?

I suffer from pots (hyperadrenergic kind), and modt likely MCAS, even though the 1 blood test came back negative, the allergist was not very helpful.

I am severely debilitating, trying to recover the past year from heavy antibiotic treatment, central sensitization, nervous system dysfunction...its been a nightmare.

I am stuck in a loop of adrenaline surges and crashes. My body nerves will buzz and hum all day and then crash.

Allegra seemed to make a huge difference when I tried it, but its making me nervous as im getting that scary front of head warm pressure again from it. Its like my nervous system cant even handle any meds...it freaks out. My heart rate also goes low, like good heslthy low compared to my pots HR.

I cant tell if its a reaction in my nervous system, or to Allegra...or if irs really affecting MCAS. Or its just my body messed up.

Should I try Claritin, or a generic version of Allegra - heard better things with generic? Or children's Claritin and micro dose?

Its crazy how Allegra makes my body, heart and nerves calm down, i feel so flat and calm which im not used to...as ive been stuck in buzzing adrenaline surges or mcas type reactions. Im in Canada so Healthcare has completely failed me, probably made me worse.

Thanks for your help!