r/MCAS
51k members
r/MCAS is a subreddit with 51k members. The most common kinds of discussions are advice requests and pain & anger, and the community frequently discusses mcas, symptoms, allergies, diagnosis, and doctor, and they frequently recommend/review antihistamine, electrolyte drink, and antihistamines.
A science-focused sub for Mast Cell Activation Disorders.
Please note: The content on this subreddit is not intended as, and is not a substitute for, medical advice or diagnosis. It must not be interpreted as such. You are strongly advised to consult your own qualified healthcare professionals for any medical questions or concerns.
Popular Themes in r/MCAS
#1
Advice Requests
: "Extreme fatigue after smelling scents?"
4 posts
#2
Pain & Anger
: "Rude medical staff… am I the only one?"
3 posts
Popular Topics in r/MCAS
#1
Mcas
: "The Shared Biology of Mcas, Histamine Issues, (h)EDS, POTS, Endometriosis, PMDD, Neurodivergence, CPTSD, Chronic Pain, and Lipedema"
277 posts
#2
Symptoms
: "Are your Symptoms worse in the city and better in rural/seaside locations?"
117 posts
#3
Allergies
: "Having trouble convincing my allergist it's not just Allergies."
38 posts
#4
Diagnosis
: "Finally found a nutritional drink!!!"
35 posts
#5
Doctor
29 posts
#6
Struggling
25 posts
#7
Treatment
: "for those of you who have stabalised your MCAS, what would you do if you were starting over again to speed up the process?"
24 posts
#8
Worst
21 posts
#9
Medications
: "Finally found a nutritional drink!!!"
21 posts
#10
Medication
: "Ketotifen"
19 posts
Products Discussed in r/MCAS
Antihistamine
64 reviews
#1
Allegra
4.3★ from 8 reviews
#2
Xyzal
4.0★ from 5 reviews
#3
Claritin
3.8★ from 5 reviews
Electrolyte Drink
58 reviews
#1
LMNT
4.3★ from 10 reviews
#2
Buoy
4.0★ from 4 reviews
#3
Gatorade
4.7★ from 3 reviews
Antihistamines
36 reviews
#1
Cromolyn
4.0★ from 6 reviews
#2
Zyrtec
3.5★ from 6 reviews
#3
Xolair
4.0★ from 4 reviews
Member Growth in r/MCAS
Yearly
+20k members(67.4%)
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About
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This page gives a focused view of r/MCAS, including current member size, discussion patterns, product reviews, and related communities to explore.
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Last updated: June 1, 2026