Got Fibromyalgia & Sensitive to Everything? Part 1: Mast Cell Activation Syndrome

Published: October 31, 2019

Sensitive to Everything

Many people with fibromyalgia are incredibly sensitive to any treatments. Especially to medications, but sometimes also to herbals, nutrients, their environment, and even electromagnetic fields (EMFs) such as radiation from cell phones. This makes it very tricky to take anything to recover.

But the good news is that you can overcome this problem.

In this article series, I'm going to discuss some of the major triggers that can cause you to have severe sensitivities to your environment and to your treatment options, and show you how to effectively deal with this. The seven-part series includes:

  1. Mast Cell Activation Syndrome (MCAS)
  2. Food Sensitivities
  3. Neurologic Triggers
  4. A Primer on Molds
  5. Treatment for Mold Exposure
  6. Doing Your Own Research on Molds
  7. Bartonella

In this first part, I begin with the topic of Mast Cell Activation Syndrome (MCAS). This is a good starter as it's easy and inexpensive to deal with, and the treatment is often highly effective.

Mast Cell Activation Syndrome (MCAS)

Mast cells are part of your immune system. They act as your body's "first responders" to protect you from anything you come into contact with from the outside world that it finds potentially harmful. When this happens, they react by releasing over 200 chemicals into your body in order to produce an inflammation, which helps your body heal. The most prominent of these chemicals is histamine, which is one reason why antihistamines are a mainstay of treating allergies.

Just as fibromyalgia can put your immune system in a continuous state of overdrive, some people have mast cells in continuous overdrive. These guardians then develop itchy trigger fingers, causing them to react to your environment seemingly at random.

Random is the key word here, as this characteristic helps distinguish mast cell activation syndrome (MCAS) from normal allergies and sensitivities. One day you have no reaction to being exposed to a particular element in your environmental, and the next day you react excessively to the very same thing. So, no problem eating an ear of corn on Monday. But bite into another corncob on Tuesday and you might feel flushed and nauseous, with diarrhea, sweating and palpitations.

Interestingly, most of the brain's histamine is located in the hypothalamus, which is connected by blood vessels to the pituitary gland. Mast cells are also found in the pituitary gland. Because of this relationship, Dr. Theoharis Theoharides MD PhD — one of the main researchers on MCAS — theorizes that elevated histamine and MCAS may be triggers for many people with CFS and fibromyalgia. These mast cells may also be a major trigger for microglial cells pouring out inflammatory factors (central sensitization), even in response to only minimal stress.

Testing for MCAS

MCAS is difficult to diagnose through testing. And since roughly half of those with fibromyalgia who are also experiencing unusual sensitivities likely have the condition, and because treatment is simple, it's better to simply diagnose based on the symptoms and response to treatment. Below are treaments I recommend trying.


I usually suggest trying these treatments in the following order:

  1. Quercetin. This bioflavonoid is a cousin to vitamin C. It helps stabilize the mast cells, kind of like calming down and soothing a crying baby. Start with 500 mg a day. If your main sensitivities are to foods, take it about 30 minutes before major meals so it can be in place when you eat. This simple supplement can often be very, very helpful, and is low-cost. You can find it in any health food store. After a few days, you can increase to 500 mg (or even 1,000 mg) 2-4 times daily.
  2. Montelukast (Singulair) 10 mg at bedtime. This prescription asthma medication is only $0.30 a day if you use the remarkable smartphone app from GoodRx (a free app that gives you discounts on prescription medications), and most physicians will be comfortable letting you try it.
  3. Loratadine (Claritin) 10 mg in the morning. If this over-the-counter medication makes you drowsy, you can use it at bedtime or try cetirizine (Zyrtec). If you have any other side effects to these medications, it's likely caused by the binders or fillers rather than the medication itself. In that case, try a different brand or have it made by a compounding pharmacy without the fillers. If this medication helps, consider diphenhydramine (Benadryl) 12.5-50 mg at bedtime.
  4. Some people will get additional benefits by adding ranitidine (Zantac) 150 mg twice a day, famotidine (Pepcid) 20 mg twice a day or even cimetidine (Tagamet) 150-300 mg twice daily. These acid blocking medications are actually also antihistamines.
  5. Caution: Do not use the other acid blocking medications (called PPIs). They will not help here and are quite toxic long term.

    Tagamet, Pepcid, and Zantac have the additional benefit of modifying immune function quite dramatically in ways that can be beneficial. Especially against Epstein-Barr virus. In fact, I have seen Tagamet knock out acute cases of Epstein-Barr (mono) in less than 24 hours. This was a tip taught to me by Dr. Jay Goldstein. The downside is that they turn off stomach acid production as well, and your body needs stomach acid to digest food. The cimetidine can be the best choice of these three for long-term use in this regard. But try them and see which one works best for you.

    These medications can work within days, though CFS/FMS expert Dr. Neil Nathan finds that it may take up to two months to see the full effect.

  6. The supplement DAO (Umbrellex) taken 15-30 minutes before eating can be helpful. Unfortunately it costs about a dollar per capsule. But it's worth a try. DAO contains the enzyme diamine oxidase, which helps break down histamine. Starting with one capsule taken thirty minutes before a meal, the dosage can be increased to two to three capsules before each meal.
  7. Cromolyn (Rx – gastrocom) ampules (100 mg in 5 mL). One taken before each meal can be quite effective for histamine reactions to food. It's relatively expensive and often not covered by insurance. But using the GoodRx app can usually reduce the price to about a $1.60 per ampule.
  8. In persistent severe cases, consider a low histamine diet (these can be found online). Though this is quite a nuisance and I rarely recommend it.

Dr. Theoharides is now exploring the possibility that intranasal curcumin and luteolin (a bioflavonoid related to quercetin) may also be especially helpful for controlling MCAS. The highly absorbed form of curcumin found in Curamin® (by Terry Naturally) may have similar benefits as the intranasal.

When problems persist, that's the time to consider looking for and treating mycotoxins (mold toxins) and the Lyme co-infection Bartonella. If you are considering these, I strongly recommend reading the book Toxic by my friend Dr. Neil Nathan. He is one of the most gifted and experienced fibromyalgia physicians for addressing this area. I will also be discussing these topics in upcoming articles in this seven-part series.

Next up in this series: "Got Fibro & Sensitive to Everything? Part 2: Food Sensitivities."

Jacob Teitelbaum, MD

is one of the world's leading integrative medical authorities on fibromyalgia and chronic fatigue. He is the lead author of eight research studies on their effective treatments, and has published numerous health & wellness books, including the bestseller on fibromyalgia From Fatigued to Fantastic! and The Fatigue and Fibromyalgia Solution. His newest book (June 10, 2024) is You Can Heal From Long COVID. Dr. Teitelbaum is one of the most frequently quoted fibromyalgia experts in the world and appears often as a guest on news and talk shows nationwide including Good Morning America, The Dr. Oz Show, Oprah & Friends, CNN, and Fox News Health.

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