are mast cell issues treated?
many cases, an over-the-counter antihistamine may be all that
needed. But different types of antihistamines are available,
in order to make the right choice, it's necessary to have a basic
understanding of how the different types work, and which symptoms they
are most useful for suppressing.
that histamine is not
just involved with causing allergy symptoms. Histamine is
responsible for providing numerous vital chemical and neuronal
functions, in order to keep various systems operating smoothly, and it
accomplishes these various tasks by attaching to histamine receptors at
various locations in the body. When histamine attaches to a
histamine receptor, this bonding triggers the subsequent events that
either provide a beneficial action, (such as increasing
the acidity of the stomach, in preparation for digesting a
or cause an undesirable response, (such as an allergy symptom).
There are basically 4 different types of histamine receptors
various organs of the body, specified as H1, H2, H3, and H4.
most common is the H1 receptor, which is found throughout the body in
smooth muscles (including the heart), blood vessels, and in the central
nervous system. When histamine attaches to these receptors,
bonding typically results in smooth muscle contractions (which can
cause constriction of broncial tubes and contractions in both
small and large intestines, for example), dilation of blood vessels,
itching, watery eyes, runny nose, sneezing, and in the case of insect
stings, pain. In severe cases, the response can include
anaphylaxis, which can result in life-threatening symptoms.
receptors also cause blood vessels to dialate, but their primary
purpose is to stimulate the production of gastric acid, when they are
activated. And their activation can result in the relaxation
smoooth muscle tissue (primarily in the digestive system).1
This is in direct contrast with the function of H1 receptors,
which induce smooth muscle contractions (rather than relaxation).
Note that activated H2 receptors are also capable of
production of antibodies, T cells, and cytokines.
This appears to explain why the use of H2 type antihistamines
trigger inflammation and microscopic colitis symptoms in some cases
(because they limit or eliminate the natural tendency of
histamine activated H2 receptors to suppress the proliferation of antibodies, T cells, and cytokines). H2 antihistamines are used
primarily to suppress the production of gastric acid, in order to treat
conditions such as peptic
gastroesophageal reflux disease (GERD), but they are clearly not
without risk, especially for certain individuals who have microscopic
receptors are found primarily in the brain and in the central nervous
system, and to a lesser degree, in the peripheral nervous system.
When H3 receptors are activated, they tend to suppress the
release of neurotransmitters, such as histamine, acetylcholine,
norepinephrine, and serotonin. Since the suppression of those
items is generally a desired effect, (for someone who has microscopic
colitis), using an H3 antagonist would appear to be generally
counterproductive. Therefore, H3 receptors and H3 antagonists
are not of interest to
us in this discussion.
H4 receptors are found in leukocytes
(white blood cells) known as basophils, bone marrow, the thymus,
spleen, small intestine, and colon. H4 receptors are
Since chemotaxis is a chemical phenomenon
primarily associated with the navigation of bacteria and certain
similar processes, it's outside the range of interest for this article,
so H4 receptors are also irrelevant to this discussion about mast cell
Note the differences between H1 and H2 receptors:
When activated, H1 receptors cause smooth muscle contraction, while H2
receptors can cause smooth muscle relaxation (particularly in the
intestines). In addition, activated H2 receptors can suppress
production of antibodies, T cells, and cytokines, all of which are
2. This implies that the use of H1
antihistamines should reduce the dilation of blood vessels, and
suppress most or all of the common allergy symptoms. H1
antihistamines should also relax smooth muscle contractions that are
induced by histamine-based reactions.
3. By comparison, the use
of H2 antihistamines should suppress the production of acid in the
stomach, reduce the dilation of blood vessels, and may induce
contractions in smooth muscle tissue, under certain conditions.
It may also cause an increase in the production of
cells and cytokines, resulting in a proinflammatory condition.
muscle contractions in the intestines can lead to a reduction in
motility (which might be helpful for reducing diarrhea), and excessive
amounts might possibly lead to cramps and even constipation.
attribute can be helpful for controlling diarrhea associated with
microscopic colitis, but in some cases, the increase in proinflammatory
agents due to the use of H2 antihistamines apparently trumps any
advantage that might otherwise be gained by reduced motility.
general, H1 type antihistamines are used as
anti-allergic drugs (since they are primarily associated with IgE-based
reactions). It's tempting to view antihistamines as
receptor antagonists, but both H1 and H2 type antihistamines are not
actually true H1 antagonists — they are inverse agonists. A
receptor antagonist works by bonding to a receptor in order to block
any subsequent attachment of an antigen to that receptor — in this case
it would prevent histamine from attaching to a receptor. An
inverse agonist goes farther than that. An inverse agonist
actually induces a
pharmacological response that is the direct opposite of the response
normally produced by an agonist (in this case, the agonist would be
histamine). In other words, not only do inverse agonists
histamine from bonding with a receptor, but they also suppress the
active functional level of the receptor to below it's normal state.
This is the reason why taking antihistamines when they are
needed, can constrict blood vessels (to increase blood pressure), cause
dry eye, dry out nasal passages, and cause similar effects that are
opposite to the symptoms caused by histamines.
I'd like to make
an observation here. In view of the
fact that one of
the symptoms of histamine is smooth muscle contraction, and bearing in
that both H1 and H2 antihistamines are inverse
that implies that an H1 antihistamine should
be capable of relaxing smooth muscle contractions in the intestines,
resulting in reduced motility. Perhaps this is why some
who have microscopic colitis have found that certain antihistamines
seem to control their diarrhea issues as well as a corticosteroid, for
all practical purposes.
cases where H1 antihistamines show
no benefits, or inadequate control, sometimes an H2 antihistamine,
either alone, or in combination with one or more H1 antihistamines, can
Typically, H1 antihistamines either help, or show no
Unless an actual allergy to the antihistamine itself, or to
of the inactive ingredients exists, H1 antihistamines virtually never
make symptoms significantly worse.
On the other hand, while H2 antihistamines may be beneficial
certain cases (either alone or in combination with an H1
antihistamine), in some situations, they can cause significant adverse
such as increased inflammation. Therefore a decision to try
antihistamine should be weighed carefully, since they carry risks that
are not associated with H1 antihistamines, especially for individuals
who have microscopic colitis.
The bottom line is, some
individuals find that one or more antihistamines can control their
symptoms as well or better than a treatment regimen based on the use of
a corticosteroid, and the risk of significant side effects (at least
antihistamines), appears to be rather miniscule when compared with the
risk of side
effects associated with treatment programs using corticosteroids.
antihistamines come in two basic types, short-acting and long-acting.
Short-acting antihistamines are typically older medications
have been available for many years, and they tend to
cause drowsiness, significant enough to interfere with work
other daily routines. An example of this is Benadryl
(diphenhydramine), which works very well for many people, but the
sleepiness that it causes can definitely be troublesome in many
situations. Another example is Chlor-Trimeton (chlorpheniramine), and a long-acting
version is available by prescription.
antihistamines are usually newer medications, and most of them are less
likely to cause drowsiness. Claritin (loratidine), Zyrtec
(cetirizine), and Allegra (fexofenadine) are all long-acting
antihistamines, and they are available without a prescription.
Prescription long-acting antihistamines are also available,
including Atarax (hydroxyzine) and Periactin (cyproheptadine).
Unfortunately, both of these drugs tend to cause drowsiness.
A presctiption H1 anthistamine that is less likely to cause
drowsiness is Xyzal (levocetirizine).
Examples of type H2
antihistamines include Zantac (ranitidine), Tagamet (cimetidine), and
Pepcid (famotidine). These drugs were originally developed to
treat ulcers, and they are frequently prescribed to treat indigestion,
acid reflux, and gastroesophageal reflux disease (GERD), but many
doctors also recommend their use for treating certain allergy symptoms,
such as rash or hives.
Examples of H1 and H2 antihistamines can be readily found on the
internet.2 Specialists who are
familiar with the treatment of mast cell
issues frequently prescribe dosage rates of antihistamines up to 4
times the maximum recommended dosages specified on the labels,
especially in cases where
symptoms include a persistent rash.3
Other treatments are also sometimes helpful for controlling mast cell
For example, avoiding foods that are high in histamine
and/or foods that promote the degranulation of mast cells, is an
effective, and safe way to reduce mast cell problems.5, 6
anyone who is sensitive to NSAIDs (as many of us are), limiting foods
in the diet that are high in salicylates can be helpful, because for
those individuals who have an IBD and who are sensitive to salicylates
(NSAIDs are derived from salicylic acid), salicylates stimulate the
production of proinflammatory leukotrienes.7
impossible to avoid salicylates complete, because virtually all foods
contain some amount. The trick is to limit the total amount
the diet, to keep it below a certain threshold that our immune system
can handle.8, 9
a mast cell stabilizer, such as cromolyn sodium can help to prevent
mast cells from degranulating. Other drugs of this
type include lodoxamide, nedocromil sodium,
hydrochloride, and pemirolast potassium. These medications work by stabilizing the membranes of
shows that people who have an inflammatory bowel disease, or food
allergies, often have a deficiency of diamine oxidase (DAO) enzyme.10,
DAO serves to remove surplus histamine from circulation in
body. If DAO is deficient, then residual histamine levels can
build up to levels where histamine becomes a problem.
in some cases, a DAO supplement may be helpful.
are known to suppress inflammation, and it appears that the mechanism
by which they accomplish that purpose, involves the reduction
of mast cell numbers.13
Some drugs are known to
interfere with the production or function of DAO, and other drugs
promote the release of histamine by other means. Examples of
drugs can be found in research articles on the internet.14
so many ways that mast cells can be triggered to inappropriately
degranulate, and other ways for histamine to build up to excessive
levels in the body, it's no wonder that mast cells are a major problem
for anyone who has an inflammatory bowel disease, or food
sensitivities. And for many of us, appropriately treating
cell issues may hold the key to our remission.
of histamine H1-, H2- and H3-receptor selective drugs on the mechanical
activity of guinea-pig small and large intestine
Cells in Gastrointestinal Disease
That Contain Histamine Or Cause The Body To Release Histamine,
Including Fermented Foods
Associated with Mesalamine in a Patient with Chronic Nongranulomatous
High in Salicylic Acid
Sensitivity Food Guide
intestinal diamine oxidase (DAO) activity in Crohn's disease: a new
marker for disease assessment?
oxidase activities in the large bowel mucosa of ulcerative colitis
and topographical distribution of gut diamine oxidase activity in
patients with food allergy
treatment reduces mast cell numbers in inflammatory bowel disease
and histamine intolerance1,2,3