Months after I took my last dose of a benzodiazepine, after a too-fast taper, I still had nasal congestion and all the symptoms of a mild flu. At one my point, my sinuses were completely blocked and a cough developed (you can read my full story for my history of Valium and Ativan use).

I was taking COVID tests every other day. They were all negative.

Eventually I went to see a general practitioner. My blood tests and physical examination were normal except for severely inflamed nasal passages.

He told me to sleep with the air-conditioning off and take anti-histamines. He also prescribed a nasal steroid. Of course, none of this did anything to address the root cause of my symptoms. They continued with no end in sight.

Maybe I just had the benzo flu?

After spending most of my waking hours on Benzo Buddies and benzo recovery subreddits, I came across other people going through benzo withdrawal that were having what they described as “benzo flu.” Others had “benzo belly,” which involved diarrhea and other GI symptoms.

Once I started reading about benzo flu, however, I realized most of those symptoms were in my rearview mirror. Anxiety, panic attacks, muscle aches and spasms, tremors, constant sweating. All of these were familiar, but outside of anxiety and the occasional panic attack, months of healing brought relief from these symptoms.

I was having more typical flu or “cold” symptoms. I continued digging on online forums. Eventually I came across the words “histamine intolerance.” There were people posting about a kind of prolonged allergic reaction. In many cases, their symptoms were similar or identical to mine.

It was around this time that I started sharing my benzo use and subsequent withdrawal with more and more friends. One of them had MCAS. She stopped me as soon as I said “histamine intolerance.” I will never forget it: “You don’t have histamine intolerance. You have mast cell activation syndrome.”

What is Mast Cell Activation Syndrome (MCAS)?

I learned that mast cells are a type of immune cell that release chemical mediators in response to perceived threats. Histamine is one of these chemical mediators. When mast cells go haywire and malfunction (as in the case of MCAS), these chemical mediators are released even though there is no threat.

The results vary from person to person. Some people break out in hives or a rash. Others have debilitating headaches. Some people – like me – have congestion, blocked ears, and post-nasal drip (UPDATE: I’ve recently added a few more symptoms to the mix: a feeling that my gums and jaw are swelling and an itching feeling, like there are ants crawling all over me. Lovely).

Are benzodiazepines mast cell stabilizers?

There are some doctors that remain skeptical due to the limited number of studies, but many are convinced that benzos are indeed mast cell stabilizers. In any case, as you’ve likely already learned, It’s hard to find much that is widely accepted in the scientific community when it comes to MCAS.

While the number of studies may not be robust, you will find no shortage of doctors that are actively prescribing benzos for their acute MCAS patients. In many cases, they try to use the lowest dose possible in order to avoid dependance (we know how this goes, but good luck to them).

To be fair, benzos are almost always the last resort. It means that the patient is not responding well enough to antihistamines, diet and lifestyle changes and possibly other supplements.

Can benzodiazepines cause Mast Cell Activation Syndrome (MCAS)?

This is the million dollar question. It is one thing to suggest that benzodiazepines are mast cell stabilizers. It is another thing entirely to suggest that the withdrawal from benzos can actually cause MCAS. The scientific, safe response is that we have no idea. There have not been any studies on this that I can see.

I would like to say that I can personally confirm that benzos cause MCAS, but even in my own case things are complicated. I certainly did not have MCAS symptoms before I started taking Valium and Ativan. That is undeniable.

But I also had several COVID infections since 2020, and we know that COVID can induce MCAS from several studies now.

Furthermore, I may not have had full blown MCAS before I started taking benzos, but I may have been genetically or otherwise pre-disposed. On my path to benzos, I mentioned having a panic attack after a game of basketball. Those with MCAS often find that their mast cells are activated during exercise, especially during intense cardio.

After playing full court basketball, I was often breathless (nearly to the point of passing out), flushed and panicked. The latter is what led me to approach the doctor from the US Embassy. Of course, these are all widely understood MCAS symptoms in the context of exercise.

It’s possible I had latent MCAS that simply had not progressed yet. Perhaps symptoms only emerged in exceptional circumstances, such as intense physical exercise. Later on, COVID infections might have aggravated my mast cells further, unbeknownst to me — I was taking benzos at that point, and they would have stabilized my mast cells.

Are we on benzodiazepines because of MCAS?

In one thread on Benzo Buddies, someone rather contentiously said, “It’s all MCAS.” They suspected that most people who were prescribed benzos actually had MCAS before they started taking them. Histamine is after all anxiogenic. They surmised a vast MCAS epidemic percolating far below the myopic eyes of psychiatry and medical research.

And you know what, it wouldn’t surprise me. It wouldn’t be the first time we would be blindsided by a groundbreaking revelation about our brains and bodies.

But for now, we are flying blind. We know that benzodiazepine use and withdrawal can mimic chronic disease symptoms. We know that benzos can act as mast cell stabilizers. As to whether benzo withdrawal can itself provoke MCAS or whether most benzo prescriptions are actually the result of MCAS, we could really use some studies!

If you have an opinion on any of this, or resources to share, it would be fantastic to hear from you in the comments below.