There's a small chance that for 4% of you, that your anxiety, depression or OCD might be caused by MCAS, an allergy-like condition which may be helped by antihistamines. (repost)

Research and education, not medical advice.

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Mast cell activation syndrome (MCAS) is an allergy-like condition that affects 4% of the population, and which can cause mental health symptoms such as:

• Anxiety
• Panic
• Depression
• Anger or irritability
• Mood lability (emotional instability)
• Obsessive compulsive symptoms
• ‘ADHD’

Reference: here.

These mental health symptoms of MCAS can be refractory to standard treatments. So if you have anxiety, depression or other mental symptoms which don’t seem to respond well to standard drug or supplement treatments, and you have physical symptoms reminiscent of MCAS with positive responses to antihistamines, then… there’s a very small but possible chance you could have MCAS, a diagnosis from a immunologist is necessary to know.

https://preview.redd.it/0h6tlcptigyg1.jpg?width=292&format=pjpg&auto=webp&s=affde84270e9e6520f79cd3393faaaa73d5fc56d

MCAS is caused when certain immune cells called mast cells release too much histamine, leukotrienes, cytokines and other chemical mediators. This can then lead to an array of physical and mental symptoms, some of which are allergy-like.

MCAS can helped with otc antihistamines such as cetirizine or loratadine. People also use ketotifen and cromolyn for MCAS. Ibuprofen is mentioned a lot but is iffy in terms of results, not first line.

The supplements luteolin or quercetin can be particularly helpful for MCAS, as they are mast cell stabilizers, and help prevent histamine release from mast cells. High-dose vitamin C may be useful for MCAS, to reduce histamine release from mast cells. Bromelain may also help reduce histamine. And the enzyme supplement diamine oxidase breaks down histamine in food, and could be useful as an adjunct.

Leukotriene Inhibitors, H2 blockers, other niche drugs and dietary changes are also official treatments for those with MCAS.

So if you have anxiety or depression that is hard to treat and you’ve noticed improvements with antihistamines , there’s a tiny chance it’s MCAS, but you need an official diagnosis to confirm so.

Treatment is highly individualized and a lot of supplements lack studies of RCTs for MCAS.

https://www.drionelahubbard.com/article/mast-cell-activation-syndrome

MCAS often comes with physical symptoms as well as mental ones; the physical symptoms are listed at the bottom of this webpage. The physical symptoms of MCAS however vary greatly from one person to the next, because the symptoms you get depend on which organs are affected by MCAS and how your body is.

Note: This is a repost for discussion purposes, original post here.

extras:

https://www.frontiersin.org/journals/cellular-neuroscience/articles/10.3389/fncel.2019.00054/full

MCs are capable of engaging in communication with neurons via CADM1. Furthermore, MCs have the ability to modulate the structural alterations of neuronal dendrites and synapses, facilitate the establishment and preservation of synaptic connections, and regulate synaptic adhesion by controlling N-cadherin. Additionally, MCs can release heparin into neurons through transgranulation to disrupt calcium homeostasis. https://www.frontiersin.org/journals/immunology/articles/10.3389/fimmu.2024.1445867/full

MCs can modulate the pro-inflammatory phenotype of microglia by enhancing the expression of cytokines and chemokines. Additionally, MC-released tryptase and histamine can activate PAR-2 receptors on microglia, ultimately leading to the induction of a robust release of pro-inflammatory factors by microglia. The histamine released by MCs can stimulate the histamine receptors on astrocytes, thereby modulating their activation. https://www.frontiersin.org/journals/immunology/articles/10.3389/fimmu.2024.1445867/full

Archived into the Nootopics wiki from r/NooTopics — originally posted by u/makefriends420 on 2026-05-01. Curated, not authored by the community.