When the Body's Alarm System Won't Stand Down: MCAS and How Stellate Ganglion Block and Ketamine Can Help
Imagine living with a security system that sounds the alarm at everything — a whiff of perfume, a change in the weather, a meal you've eaten a hundred times before. For people with Mast Cell Activation Syndrome (MCAS), that's not a metaphor. It's daily life. At StrIVeMD Wellness and Ketamine, we care for patients whose symptoms have never fit neatly into a single diagnosis, and increasingly we're seeing how two of our core therapies — the stellate ganglion block (SGB) and IV ketamine — can help quiet an overactive system when conventional approaches fall short.
What Is MCAS?
Mast cells are part of your immune system's first line of defense. They're stationed throughout your body — in your skin, gut, airways, and around blood vessels and nerves — and when they sense a threat, they release chemical mediators like histamine, tryptase, and prostaglandins. That response is supposed to be protective.
In MCAS, the problem isn't how many mast cells you have; it's how they behave. The activation threshold is lowered, and these cells fire too easily in response to triggers that shouldn't provoke a reaction at all. Because mast cells live all over the body, the fallout is multisystem and episodic. Common symptoms include flushing, hives, and swelling; abdominal cramping, nausea, and diarrhea; a racing heart, lightheadedness, or drops in blood pressure; wheezing or chest tightness; and the frustrating cognitive haze so many patients describe as "brain fog." Diagnosis generally requires recurrent symptoms across two or more organ systems, laboratory evidence of mediator release, and improvement with medications that block those mediators.
MCAS is also, frankly, a contested and often-missed diagnosis. Many patients spend years bouncing between specialists before anyone connects the dots — and it frequently overlaps with conditions like POTS (postural orthostatic tachycardia syndrome), dysautonomia, hypermobility, and long COVID. Standard care starts with mast-cell-directed medications: H1 and H2 antihistamines, mast cell stabilizers such as cromolyn and ketotifen, and leukotriene inhibitors. For many people, that's enough. But for a significant group, symptoms remain stubbornly refractory, and quality of life stays low. That's where a different lens becomes valuable.
The Neuro-Immune Connection
Here's a piece of the puzzle that's reshaping how complex, multi-system patients are treated: the nervous system and the immune system are not separate. They talk to each other constantly.
Mast cells physically sit alongside nerves and can both respond to and influence neural signaling. Nerve-derived chemical messengers can nudge mast cells toward activation — which helps explain why so many patients notice their symptoms flare during stress, illness, poor sleep, or the physical strain of standing up. When the sympathetic nervous system — your "fight or flight" branch — is stuck in overdrive, it may be helping to keep mast cells on a hair trigger. Calm the autonomic storm, the reasoning goes, and you may reduce the frequency and intensity of mast cell flares.
This is exactly the pathway our two signature therapies are designed to influence.
Stellate Ganglion Block: Resetting the Autonomic Thermostat
The stellate ganglion is a cluster of sympathetic nerves in the front of the neck, part of the cervical sympathetic chain that helps govern your stress response. A stellate ganglion block is a targeted injection of local anesthetic near this bundle — and at StrIVeMD we perform it under ultrasound guidance, which lets our providers see the carotid artery, jugular vein, thyroid, and surrounding structures in real time for a safer, more precise placement than blind or x-ray-guided techniques.
By temporarily interrupting sympathetic signaling, SGB can effectively "reset" an overactive autonomic nervous system. It's already an established tool for PTSD and certain chronic pain conditions, and encouraging early signals have emerged in closely related autonomic disorders — most notably long COVID and POTS, which share so much biological territory with MCAS. For patients whose mast cell symptoms worsen with stress and autonomic arousal, dialing down that sympathetic overdrive offers a mechanistically sensible way to lower the baseline "alarm level."
An honest note: SGB has not yet been formally studied in MCAS specifically. The rationale is strong and the overlap with conditions where it has shown promise is striking, but we consider it a thoughtful, individualized part of a broader plan — not a stand-alone cure.
Ketamine: Calming a Sensitized System
Ketamine has earned attention well beyond its origins as an anesthetic, and its relevance to MCAS patients comes from several directions at once.
As an NMDA-receptor antagonist, ketamine interrupts central sensitization — the process by which the nervous system becomes hypersensitive and amplifies signals long after any original trigger. Many MCAS patients live with widespread pain, heightened sensitivity, and nociplastic pain that behaves like a software glitch in pain processing. Ketamine can help interrupt that cycle. It also carries genuine anti-inflammatory properties, having been shown to reduce microglial activation and pro-inflammatory cytokines like TNF and IL-6 — the same inflammatory chemistry that keeps sensitized, neuro-immune systems inflamed. And through its effects on neuroplasticity and mood, ketamine can ease the anxiety, depression, and brain fog that so often ride alongside chronic mast cell disease.
At StrIVeMD, ketamine is typically delivered as a closely monitored IV infusion lasting roughly 40 to 60 minutes, in a comfortable, supervised setting. As with SGB, we're candid that robust MCAS-specific trials are still limited; what ketamine reliably addresses is the heavy downstream burden — pain, sensitization, and mood — that makes living with MCAS so exhausting.
An Integrated Approach
We don't view SGB and ketamine as replacements for antihistamines, mast cell stabilizers, and the trigger-avoidance strategies that form the backbone of MCAS care. We view them as powerful complements — tools that address the neuro-immune dimension of a condition that has too often been treated as purely allergic. Both therapies dampen sympathetic overdrive, lower the body's stress-hormone output, and reduce inflammation, which is why they can work synergistically for the right patient.
If you've done everything "by the book" and still feel like your body's alarm won't stand down, these emerging therapies may be worth a conversation. Every plan we build is personalized and starts with a thorough consultation and an accurate diagnosis.
This article is for educational purposes and does not constitute medical advice. The use of stellate ganglion block and ketamine for MCAS is emerging and considered off-label; individual results vary. Please consult a qualified provider trained in anesthesiology and pain medicine — like our team at StrIVeMD Wellness and Ketamine — to determine whether these treatments are appropriate for you.