Showing posts with label Claritin. Show all posts
Showing posts with label Claritin. Show all posts

Tuesday 12 May 2015

Minimizing Summertime Autism Flare-ups in 2015

When I first connected histamine to autism, I did not realize that this might be a common problem.  The most frequently viewed post on this blog is one on histamine and autism; so at least 10,000 people out there have googled “autism and histamine”.

Two years later, the therapy is still evolving and it should be said that, what works best for one person may not help in another person.  The main point is that in some people with autism, they face a summertime regression due to the effect of allergy.  So bad behaviours and aggression increase and good behaviours and indeed cognitive function decrease.  This appears to be the result of histamine and a pro-inflammatory cytokine called IL-6.

For the 2015 pollen season, which started early where we live, this is what we are using:-

Azelastine nasal spray, this is an H1 antihistamine that is also inhibits mast cells from “degranulating” and emptying their load of pro-inflammatory substances.  Once a day.

Quercetin is a cheap flavonoid that has numerous actions including on histamine H1 receptors, mast cells, and inflammation. 125mg two or three times a day.

Verapamil is an L-type calcium channel blocker and also a mast cell stabilizer. 40mg three times a day

Fluticasone propionate 50 µg (micrograms) – see below.  It is a steroid that has recently been shown to have some unexpected effects on mast cells.  

I have found that oral antihistamines were effective for only a couple of hours, but their effect varies widely from person to person.

In theory, Rupatadine should be the most effective anti-histamine, since it is also a potent mast cell stabilizer.  The old first generation antihistamines (that make you drowsy) could in theory be better than the new ones like Claritin, Zyrtec, since they can also cross the blood brain barrier (BBB).

Ketotifen and cromolyn sodium should also be useful, but if the allergy is pollen related, you really need the nasal spray (nasalcrom etc) to get the most effect.  In some countries they sell eye drops and not the nasal spray.  Usually the eye drops are more diluted than the nasal spray.  For example, the Azelastine eye drops contain 50% less Azelastine than the nasal spray, but are otherwise the same.  Where we live they have run out of the nasal spray but not the eye drops, so you could refill the spray with eye drops and double the number of sprays to get the same dose.

Drugs like Claritin and Zyrtec are H1 antihistamines and also partial mast cell stabilizers; they have a positive behavioral effect in some people with ASD, who are apparently allergy free.

New for 2015

I expect that two recent anti-inflammatory therapies, the Tangeretin flavonoid and the Miyairi 588 bacteria/probiotic may have a beneficial, indirect, effect on our usual summertime regression.

A more convention approach is to add fluticasone propionate to reduce the inflammation caused by allergy.  This drug is a steroid and widely used either as an inhaler to control asthma and COPD, or as a nasal spray to treat allergies.

As Flixotide inhaler, Monty, aged 11 with ASD and asthma, has already been taking fluticasone propionate for a few years.  We now use a tiny dose (50 µg), since his autism therapies have greatly reduced any asthma tendencies.

Fluticasone propionate nasal spray (Flixonase, Flonase etc) is widely sold as a treatment for hay fever and rhinitis and was recently combined with Azelastine (see above) as a treatment for moderate to severe allergies in a product call Dymista.

The combination of H1 antihistamine, mast cell stabilizer and anti-inflammatory all in one spray does seem a good idea.  The steroid dose using Dymista is actually lower than the usual dose of steroid when using Fluticasone propionate nasal spray alone.  You want to minimize the amount of steroid absorbed in the blood. When used as a spray/inhaler the amount is tiny, but still should be considered.

Dymista (Azelastine + Fluticasone propionate) does indeed work better than Azelastine alone.  There is no sign of allergy at all (no red eyes, sneezing, itchy nose), with Azelastine you still have an itchy nose.

In our case, the allergy symptoms, even minors ones, do correlate with the change in behaviour and cognitive function; so the target is no allergy symptoms at all.

If anyone has other therapies for summertime flare ups, feel free to share them.

Monday 24 March 2014

Summertime Raging in Autism – H1 Anti-histamine Effect on Histamine Levels and IL-6

Last summer, I wrote a lot about autism getting much worse in that time of the year and how I found that common “24 hour” anti-histamine drugs seemed to have a magical effect; but one that lasted only 2-3 hours. There were only visible signs of a mild allergy, which could indeed easily be overlooked.

I did later receive a message from a reader who noticed his child’s ASD behaviours were greatly improved by Zrtec and his doctor agreed to prescribe this H1 antihistamine all year round.

Recently, I stumbled upon a blog, rich with many comments of parents of kids with severer types of autism.  Here I noted some parents referring to “summertime raging”, and I thought to myself, I know what they mean.  Fortunately, I found out how to make it go away.

Ant-histamine drugs

The two most common antihistamine drugs are Claritin (Loratadine), its active derivative Aerius (Desloratadine) and Zrtec (Ceterizine) and its active derivative Xyzal (levocetirizine).

The main action of an antihistamine is not actually to reduce the amount of histamine in your blood, rather it is to block the effect of histamine on the H1 receptors.

An H2 antihistamine blocks H2 receptors that are mainly in your intestines, and is used to reduce the amount of acid in the stomach.

This led me on a quest for substances that actually stop the increase in histamine, rather than just blocking some effects.  The only thing that does this is something that can stop so-called mast cells from degranulating and spilling their load of histamine, serotonin, nerve growth factor and cytokines, including IL-6, into the blood; from where, all except serotonin, are free to travel to the brain, across the blood brain barrier (BBB).  Serotonin cannot cross the BBB.

According to the mast cell specialist Theoharides, conventional drugs are not genuine mast cell stabilizers.  There are some partial ones, like Ketotifen, Cromalin, Rupatadine and Azelastine, but Theoharides thinks naturally occurring flavonoids like Luteolin and Quercetin work best.

Last summer in this blog I looked at newly discovered histamine receptors types H3 and H4 which are known to be present in the brain.

So how is it that Claritin and Zrtec can reduce autistic behaviours ?

I did note that both the above drugs did reduce summertime raging and also the Theoharides' research that showed they probably should not, since they are not mast cell stabilizers. 

Since my blog reader also found Zrtec helpful, so much so he gives it to his kid year round and it now seems summertime raging is not an unusual phenomenon in autism, I did some more checking.

In spite of what Theoharides tells us, it turns out that both Claritin and Zrtec do indeed reduce the amount of histamine in the blood.

Also, it turns out that not only is the pro-inflammatory cytokine IL-6 released from mast cells but it is also released from another type of cell, called the endothelial cell.

The endothelium is the thin layer of cells that lines the interior surface of blood vessels and lymphatic vessels, forming an interface between circulating blood or lymph in the lumen and the rest of the vessel wall. The cells that form the endothelium are called endothelial cells. Endothelial cells in direct contact with blood are called vascular endothelial cells, whereas those in direct contact with lymph are known as lymphatic endothelial cells.

And what prompts endothelial cells to release IL-6? Histamine does.

Indeed we have studies showing how Claritin (loratadine) and  Zrtec (Ceterizine) reduce histamine and IL-6; it is the IL-6 from the endothelial cells.


These results demonstrate that both L and DCL are active to reduce the histamine-induced activation of EC. Interestingly, DCL seems to be effective at lesser concentrations especially to inhibit cytokine secretion."

The above study would suggest that Aerius (DCL) should be more effective than Claritin (L) its predecessor.

"Histamine is a major constituent of the mast cell. The effect of histamine on endothelial cells is primarily mediated through H1R

Collectively, our results suggest that mast cell-derived histamine and proteases play an important role in vascular inflammation and calcification in addition to their well-recognized participation in allergic diseases."

This study, and others like it, show how mast cell degranulation contributes to heart disease.  This would suggest that mast cell stabilizers have a much wider role in human health than is realized.  Another example of how a red apple a day (with the skin) may indeed help keep the doctor away and a glass of red wine will do the same.  Both are rich sources of the mast stabilizer Quercetin.  The alcohol increases the bio-availability.


These results suggest that cetirizine exerts its beneficial effects on viral myocarditis by suppressing expression of pro-inflammatory cytokines, genes related to cardiac remodeling in the hearts of mice."

So how do Claritin and Zrtec reduce summertime/year round raging in autism?  Well it could be histamine or it could be IL-6, we cannot know for sure.  The science tells us that the brain has many H3 and H4 receptors, so they are possibly to be implicated.  Or, it may just be IL-6;  histamine’s involvement could be just provoking the endothelial cells to release more IL-6.


Claritin/Zrtec/Xyzal are relatively cheap, in theory they are long lasting drugs.  In Monty, aged 10 with ASD, they all work for summertime time raging, but not for long.  Adults should take one per 24 hours.  Monty would need one every 3 hours.

The, supposedly better, mast cell stabilizers like Ketotifen and Rupatadine take a few days before they have any effect at all.  Azelastin is available as a nasal spray and is supposed to be effective quickly as an allergy treatment.

My preferred mast cell stabilizing, IL-6 inhibiting, strategy is to combine PEA (palmitoylethanolamide) which is already naturally in your body, with the flavonoid quercetin, which is found in the skin of red apples and red grapes.  In theory, according to the research, this is both a potent combination and should be free of harmful side effects.

Very frequent doses of Claritin/Zrtec/Xyzal are not going to be good.



On this blog:-

Sunday 6 October 2013

Autism - Drugs and Supplements that actually do work

Following requests for more information about supplements and drugs that really do seem to help with autistic behaviours, I have updated my "Top Tips" page.  Here is the updated information for anyone who is interested.

You will find links to the science behind all these ideas in various posts on my blog.  Many of these are "off label" applications, since there are no treatments yet  licensed for autism.

From comments received, it is clear people want "supplements" because they are available without prescription.  The rules vary widely from country to country.  A supplement in the US may be a drug in the UK and vica versa.  Or even a drug in UK is a supplement in Germany.  Just do some research on the internet.
Since I am not a doctor, this is not medical advice.  Since your doctor does not read the autism research, he/she will probably not be able to help you.


Science established some time ago that oxidative stress plays a central role in autism.

There is one widely available antioxidant that is highly effective. It is called NAC  (N-Acetyl Cysteine) and is available without prescription via the internet (from Amazon for example) or many pharmacies.

The result is very dose dependent.  Some people take time to adjust to it, due to mild stomach irritation.  Most supplements come in 600mg capsules.  Two capsules has an effect, but the effect becomes larger as you increase to about 3g per day (i.e. 5 capsules per day).  You should observe a great reduction in obsessive behaviours within a few days.  Then new good behaviours should emerge quite rapidly.  Speech increases.

To read about this on the blog, go to the list of labels and click on GSH.

Neuroprotection and anti-inflammatory

The research is conclusive that there is chronic neuroinflammation in autism.  The anti-oxidant will contribute to managing this, but an anti-inflammatory agent that can reach the brain will give additional benefit.

This blog has highlighted research to show that widely used drugs called Statins have a secondary effect that reduces neuroinflammation.

The Statin I choose is Atorvastatin, but Simvastatin also looks a good choice.  In the UK Simvastatin is available without prescription.

I use 10mg Atorvastatin.  The behavioural improvement was visible within two days.  New behaviours involving initiative emerge.

To read about this just click on statins in the list of labels.

GABA Neurotransmitter

Research going on for 10 years in France has shown that the widely used diuretic Bumetanide reduces the level of chloride in the brain.  The high level of chloride causes the brain neurotransmitter GABA to malfunction in autism and babies with neonatal seizures.

The effect of taking 1mg of Bumetanide has a dramatic behavioural effect.  It improves the child's ability to control himself.  He appears more "present" and not in his own world, this results in more interaction with his peers and an improvement in mood and a general increase in happiness.  Speech increases.

To read about this just click on bumetanide in the list of labels.

Autsim flare-ups  -  over activated mast cell response to allergens

Violent episodes may sometimes be provoked by an allergic reaction caused by so-called, mast cells.  What in a typical child might just cause a runny nose or sneezing, may cause violent/aggressive behaviour in a child with ASD.

A cheap over the counter drug drug called Claritin, acts as an anti-histamine H1 antagonist, it will subdue the allergic reaction within a few tens of minutes.

Many people do not respond to a particular anti-histamine, if one does not work just try a different one.  Your pharmacist can suggest an alternative (levoceterizine for example).  The brand names vary by country.

If the child complains about creepy feelings on his/her legs this would be an indicator or this type of allergic reaction.

There are other serious behavioural causes of self injury, but if the child is normally well behaved and under self control, sudden outbursts may be being triggered by mast cells.  Read all about mast cell research here.

Lower Serotonin Levels 

High serotonin levels are a known biomarker of autism;  lowering them does indeed appear to reduce autistic behaviours.   
You can do this via diet.  Avoid food known to raise serotonin, for example bananas and caffeine.  A low carbohydrate, high protein diet is known to lower serotonin levels.  The Atkins (induction phase) diet and the Ketogenic diet are also known to lower serotonin levels.  You will know if it is working because lowering serotonin increases appetite, your child should put on weight.
The easier way is with a serotonin antagonist like Periactin, often prescribed in the US to underweight children.  Periactin is a first generation antihistamine drug, so it will cause drowsiness.  It is known to be antiserotonergeric.  It is available OTC in some countries.

Read the post on Serotonin here.

Increase acetylcholine levels
The story about acetylcholine is quite complex, and the full post about it is here.
To increase acetylcholine there are various options.  The drug options shown to be effective work by affecting the enzyme acetylcholinesterase.  The two drugs shown to be effective in autism are Galantamine and Donepzil.  These are prescription drugs.
The same effect is possible using a nicotine patch, or even potentially by using nicotine gum.  One quarter of a 7mg patch applied for 6-8 hours is suggested by one US doctor.
The other method, that is sometimes combined with Donepzil, is to give the dietary supplement choline, which is widely available.

High potassium diet reduces sensory overload

If your child with ASD, like most, has a problem with sensory issues like sound, light, smell etc, there is a dietary solution.  Increase potassium in his/her diet - eat more bananas, oranges, kiwis, potatoes etc.  You can also use potassium + magnesium supplements.  If you live in the US, beware of these supplements, they are very weak.  A banana has 500mg of potassium,  US supplements contains up to 100mg, UK supplements are up to 200mg.  Magnesium plays a role as well, it is needed to maintain potassium levels.  I use a cheap French supplement with 500mg Potassium and 150 mg Magnesium, taken half AM and half PM.  Potassium supplements can irritate the stomach, but they do modify autistic behaviours for the better.
Potassium ion channels (like Kir 4.1) play a role in the brain in both ASD and epilepsy.  It is very complicated and still not fully understood, but it WORKS! 

Saturday 27 July 2013

More on anti-histamines in Autism and introducing H4

In my previous posts on histamine, you would have read that I found that Claritin appeared to reduce autistic behaviours.  Once I had got to the bottom of what was going on, I found out that histamine has a long record of stimulating challenging behaviour in all children.  It also became clear that typical anti-histamines (H1 antagonists) are all slightly different and one may be effective in one person and ineffective in another.  Each one tends to have additional secondary effects.

It now appears that the secondary effect of certain H1 antagonists may actually be more important than the primary intended effect of reducing itchy eyes and runny noses.
There are three generations of H1 drugs.  The fastest working and most potent is still the first generation, the second generation are non-drowsy derivatives of the first generation.  The third generation are the active metabolite of the second generation.  As you will see in today’s central paper, the third generation probably does not warrant the tittle.  For many users they may be just expensive versions of the second generation drug.

The excellent paper  New anti histamines: a critical view is from Brazil, but it has an English version.  It is highly readable.  It tells of the specific secondary effects of certain second generation  H1 antagonists.   (She omits to mention the secondary effects of the first generation. Some people say Ketotifen is 1st generation and other people say 2nd generation, anyway it appears not to be sold in Brazil).  I suggest you read the paper, if you have a child with an ASD. The key section is this:

Antiallergic/anti-inflammatory effects

Originally, studies of the relative potencies of H1 antihistamines were based on the capacity of different compounds to competitively inhibit the H1 receptor binding of histamine, i.e. on their blocking effect on the receptor.8 Nevertheless, it has already been known for some time that, in addition to acting on H1 receptors, many H1 antihistamines, at appropriate doses, are capable of inhibiting not only the release of histamine by mast cells,9,10 but also mast cell activation itself.11 Some of them can even regulate the expression and/or release of cytokines, chemokines, adhesion molecules and inflammatory mediators.5,8

Therefore, the antiallergic properties of H1 antihistamines are generally a reflection of their capacity to affect mast cell and basophil activity, inhibiting the release of preformed mediators such as histamine, tryptase, leukotrienes and others.8 Several second-generation H1 antihistamines have demonstrated antiallergic properties, irrespective of their interaction with the H1 receptor.5,8

Chronic allergic inflammation resulting from the late-phase reaction, exhibits components that are similar to other forms of inflammation, including chemotaxis of inflammatory cells followed by activation and proliferation, with subsequent production and release of many chemical mediators. Among cells involved in allergic inflammation are: antigen-presenting cells (for example, macrophages), mast cells, basophils, T lymphocytes, epithelial/endothelial cells and eosinophils - major effectors of chronic inflammation. Cytokines, chemokines, inflammatory mediators and adhesion molecules also contribute to this process which ultimately leads to dysfunction of the affected organ.8

Many second-generation H1 antihistamines (particularly cetirizine) are capable of inhibiting the influx of eosinophils to the site of allergen challenge in sensitized individuals.5,8 Studies have demonstrated that some of them can also alter adhesion molecules expression on epithelium and eosinophils, and reduce in vitro survival of eosinophils. Finally, some second-generation H1 antihistamines are capable, in vitro and in vivo, of altering the production of inflammatory cytokines (for example, TNF-a, IL-1b and IL-6) and the Th1/Th2 balance regulation cytokines (for example, IL-4 and IL-13).5,8

Therefore, it is well established that, in addition to their effects on H1 receptors, many second-generation H1 antihistamines also manifest antiallergic and anti-inflammatory properties which differ depending upon their molecules and the experiments used for their evaluation.5

From my own experience, I have already replaced Claritine (Loratadine) with Cetirizine to see if it will remain active for longer.  Rather than working for 24 hours, Claritine is working for about 5 hours.
I thought Cetirizine might remain active for longer, but the main difference seems to be in how it works, rather than for how long it works.  With Cetirizine autistic behaviour has pretty much returned to where it was at the start of summer, before the allergy season.  With Claritine things improved greatly, but not all the way back to "normal".

Reading the paper and one of its references -
makes me think that the expensive new  version of Cetirizine, called Levocetirizine, might be even better.  It happens to be available locally, but it is seven times as expensive.

The Brazilian paper does rather contradict some of what Dr Theoharides says about stabilizing mast cells.  You can choose who you think has got it right.  The good thing is that both Dr Inês Cristina Camelo-Nunes and Dr Theoharides seem very serious, objective people, which cannot be said about all the people offering their advice on the internet.

In fact, I found an interesting paper on the anti-inflammatory effects of the new version of Claritin, called Aerius/Clarinex (Desloratadine).

It really seems to be the case of trying several antihistamines and selecting the one that works best for you.
The H4 Histamine Receptor and Inflammation
You may recall that there is a fourth histamine receptor, naturally called H4.

It was only recently discovered, as you might guess from the short entry in Wikipedia.  It seems that the H4 receptor plays a substantial role in the inflammatory response.  It is seen as playing a key role in conditions ranging from arthritis to asthma.
Here is a full text paper for those interested in the science:-

The role of histamine H4 receptor in immune and inflammatory disorders

 Here is a graphic from that paper:-

I wonder if that H4 is a ticking bomb in autism as well ?

Those more peaceful people among you will be less aware of what C4 is, and hence the sticks of H4 dynamite.



Wednesday 24 July 2013

Histamine, allergies and reducing challenging “autistic-like” behaviours

Having recently discovered that an anti-histamine drug like Claritin can markedly reduce autistic behaviours, I have been looking into exactly why this might be and to see if there could be any other related interventions.  Here are the results and they pull together all sorts of related comorbidities and in the end I seem to have found a better solution for managing summertime autism flare-ups.

Allergies have long been linked to aggressive behaviours
It seems to be well known among allergists, that children with allergies may exhibit challenging behaviours.  It goes beyond the simple fact that the child with an allergy will be irritable and therefore behave badly; the allergy itself is affecting the behaviour.  Allergies tend to worsen behaviour and the science can explain exactly why this happens.   This applied to pollen type allergies, food allergies and even asthma.

In the case of asthma, I found several studies, one is called:  Prevalence of Behavior Problems in US Children With Asthma

The study concluded with:
Clinicians caring for children with asthma and their families should be aware of the relationship between asthma and emotional and/or behavioural problems and anticipate that a substantial number of their patients may have mental health services needs.
One alternative health website, gives a list of symptoms they believe histamine allergies produce in kids with ASD.

Some different types of responses to histamine seen in ASD children: If histamines become too high, you can see hyperactivity, compulsive behaviors, depression, abnormal fears, intense mood swings, runny nose, itchy eyes, sneezing, perfectionism, strong wills, explosive anger, anxiety, hair pulling, lack of focus, scripting (repeating commercials or television programs, etc.), high libido, giggling (which can be a sign of yeasty behaviors), aggression, change in bowel movements, a craving for salt, frequent urination and rashes. Those who have seasonal allergies tend to see a worsening of these symptoms during spring time.

 What I recently noticed in Monty, aged 10 with ASD, were some of these behavioural problems, but  with only the slightest outward sign of an allergy.
Food allergies causing autism-like behaviours
I was surprised to find one allergy site listing the behavioural effects of food allergies, it reads like a long list of autistic behaviours.  This made me wonder if many of the milder cases of autism and the so-called autism epidemic may just be unresolved food allergies.  Many of the DAN interventions are about “healing the gut”, so maybe they are really more about treating food allergies.  Many cases of classic autism appear to have no problem with their digestive system at all.

Here is a list of behaviours from one site on food allergies:
 Poor coordination

Trouble communicating

Self-destructive behavior


Difficulty in group games or sports


Nonsense talk
Inability to read tones of voice and/or body language

The best studied/documented allergies
Asthma is the best researched allergic condition that I found, followed by food allergies and the rare condition of mastocystitis; this condition is rare but sufferers write extensively about it on the internet.  They also report on the effect of different drug combinations in managing their conditions.   Mastocystitis is also a comorbidity of autism that has been researched by Theoharides, who proposes his NeuroProtek supplement.

The result is that there has been a great deal of research and many established drug therapies exist.  The link between allergies and behaviour was investigated in the 1980s, but there has not been much written since, which is a pity.

The Mastocystitis Society of Canada have a good website.  It defines Mastocytosis as a myeloproliferative neoplastic (mpn) stem cell disorder, caused by an over-abundance of good immune system cells called mast cells and the release of mast cell mediators.

What that really means is that when the mast cells encounter an allergen they overreact and release too much histamine and also inflammatory messenger, such as cytokines.  These chemical disperse throughout the body.  The histamine activates the four types of histamine receptors around the body.  The pro inflammatory cytokines react in a different way, but promote an excessive inflammatory response.
To grossly simply the condition, mastocystitis is an extreme form of allergic response.

Mastocystitis is a comorbidity of autism and the mast cell response has been proposed to be a key part of autism.  It is interesting to look at how mastocystitis is treated.  Click the link here.
Note the use of both H1 and H2 histamine antagonists, many asthma drugs including the steroid Prednisone, and the mast cell stabilizer Ketotifen.

Histamine & Histamine Antagonists

 Histamine is a chemical in your body with three distinct functions:-

1.       Histamine triggers the inflammatory response
2.       Regulates physiological function in the gut
3.       Acts as a neurotransmitter

Most histamine in the body is generated in granules in mast cells or in white blood cells called basophils. Mast cells are especially numerous at sites of potential injury — the nose, mouth, and feet, internal body surfaces, and blood vessels.

Histamine functions in coordination in 4 types of receptors (H1, H2, H3 and H4).  In the central nervous system H1 and H3 receptors.  H1 is involved in allergies and asthma.  H2 is mainly involved invasodilation and gastric acid secretion.  H3 controls neurotransmitter release (histamine, acetylcholine, norepinephrine, serotonin).  H4 Plays a role in chemotaxis.

Histamine antagonists are drugs that inhibit the action of histamine by blocking specific receptors in specific parts of the body.  The most common drugs are H1 antagonists that block the H1 receptor in summertime allergies.  H2 antagonists reduce gastric acid secretion to heal peptic ulcers.
Histamine is the link between allergies and behavioural change
Histamine in the brain has been shown to directly influence behaviour (see later in this post for links).  There is also plenty of anecdotal evidence from allergists, as shown earlier in this post.

In addition histamine has been shown to weaken the blood brain barrier.   This would then let into the brain pro-inflammatory agents that might then cause a spike in neuroinflammation and oxidative stress.  This in turn leads to more challenging behaviours.   

The disruption to the BBB can be best reduced by the use of H2 antagonist. H1 antagonists have a much smaller effect.  See this study, which concludes:

 It is concluded that histamine causes an increase in blood-brain barrier permeability which is mediated via endothelial H2 receptors,

Ketotifen is an H1 histamine antagonist.  It is a 40 year old antihistamine drug that is available over the counter in Europe.  Not only can it be used to treat  allergies (it is the active ingredient in many eye drops) and help control asthma, but it has some additional benefits.  It acts as a mast cell stabilizer, reducing the amount of histamine released by the mast cells when they encounter allergens.  It is the only  H1 histamine antagonist that does this.  In  addition it also blocks H1 receptors like the other widely used H1 histamine antagonists.
It is also used by body builders.  They are using another asthma drug called Clenbuterol.  This drug has the side effect of reducing your body mass index (BMI), so it makes you more muscular if you take enough of it for long enough.  Such use of Clenbuterol has side effects, the body builders are using Ketotifen to reduce these and allow them to use Clenbuterol for longer.  The misuse of Clenbuterol  affected beta-adrenergic receptor functions, for those who are curious.  Ketotifen blocks this from happening.

Celebrities, like a certain very well-known footballer’s wife, take Clenbuterol to stay thin.  Maybe they also take Ketotifen?
Ketotifen is extremely cheap and widely available in Europe and Canada.  In the US it is much more difficult to get hold of and so seems to have great rarity value.

In the US, some DAN doctors give Ketotifen to autistic children as a therapy for Gastrointestinal problems.  The well-known DAN doctor, with an audio lecture on this subject, states that Ketotifen is “mainly active in the gut”.  He obviously has not read the research, since the opposite is actually true.  Based on my limited research, it appears that some of these kids may just have autistic-like symptoms causes by the excess histamine in their brain. In other words they may just have a case of food intolerance / Irritable bowel syndrome rather than autism.  That would certainly be a relief to the parents concerned.
Other H1 Antagonists
You will know these drugs by their brand names :  Claritin, Zyrtec, Benadryl, Allegra, Phenergan etc.  There are several types of these drugs.  The early examples passed into the brain and so made people drowsy.  The second generation are the current big sellers, based on their non-drowsy effect.  When you dig deeper, you will see that they are all slightly different, and some work better than others in different people.  They also vary in which part of the body they have the most affect.
The older types are off patent and sold cheaply as generic over the counter drugs.

Mast cell stabilizers and irritable bowel syndrome
It has been long known that certain drugs reduce the allergic reaction in food intolerance.  Remarkably the same drugs are today also used to treat asthma.  The expensive drug I was prescribed as child called Intal (Cromoglicic acid) for food intolerance, is today called a mast cell stabilizer and  used in asthma therapy.

Mast cell stabilizers prevent the release of inflammatory chemicals like histamine from mast cells.
Another insight courtesy of the Mastocystitis Society of Canada:-

“Mast Cell Stabilizers - Ketotifen is preferred as most effective for entire body, Cromolyn mainly targets gastrointestinal system”
So it looks like the DAN doctors have chosen the wrong treatment for their GI problems, they should be using Intal not Ketotifen.

Modern second generation anti-histamines do not enter the CNS
First generation H1 antagonist crossed the blood brain barrier and had a sedative effect, making sufferers drowsy.  As a result there was a big search made of drugs that could relieve allergy symptoms but not make sufferers drowsy.  These second generation drugs are the current big sellers, although the first generation drugs are still widely available.
These modern drugs should therefore have less impact on histamine driven challenging behaviours than the old ones.
Most anti-histamines block the receptor rather reducing the amount of histamine
The popular H1 antagonist like Claritin do not reduce the amount of histamine produced in the body, they rather block the receptors used to detect it.  The amount of histamine flowing through your body remains the same.  That histamine weakens the blood brain barrier, allowing in things that might be better kept out.
It turns out that the H2 antagonists can reduce this degradation of the BBB, but H1 antagonists like Claritin have only a marginal effect.  This is all based on research in rats.

Sufferers of mastocystitis take copious amounts of H1 antagonists and H2 antagonists plus a whole host of other drugs.  H2 antagonists are old drugs like Tagamet, that were designed to reduce acidity in your stomach for treating ulcers and GERD.  It appears that also have unforeseen effects in your brain and elsewhere.
Histamine in the Brain
For those scientists among you, the areas to read up on are mast cells and how histamine functions in the brain.  Many of the papers on histamine in the brain are not available without payment.  Here is a short paper that is available.

Other good ones, not available free include:

and from way back in 1988:- 
Behavioral effects of histamine and its antagonists: a review

Research studies in to the use of H1 and H2 antagonist in autism
I was pleased to find that I was not the first to look into the use of histamine drugs in autism.  I did find two studies, and both were positive.  It is strange that in the 12 years since these studies were carried out, the research effort has not been followed up.
From my recently acquired insight, the H1 antagonist improved behaviour by blocking some of the unwanted response to histamine in the brain and the H2 antagonist help restore the blood brain barrier and keep out those unwanted pro-inflammatory agents like cytokines and perhaps even some histamine.


Niaprazine is a histamine H1-receptor antagonist with marked sedative properties. It has been employed in subjects with behavior and sleep disorders. No data concerning the use of niaprazine in subjects with autistic disorder are reported in the literature. The authors performed an open study to assess niaprazine efficacy in a sample of 25 subjects with autistic disorder and associated behavior and sleep disorders. Niaprazine was administered at 1 mg/kg/day for 60 days. A positive effect was found in 52% of patients, particularly on hyperkinesia, unstable attention, resistance to change and frustration, mild anxiety signs, heteroaggressiveness, and sleep disorders. Statistical comparison between responders and nonresponders showed no influence on niaprazine effect by age over or under 12 years, presence of neurologic signs, epilepsy, or abnormalities seen on brain imaging. Niaprazine was more efficacious in subjects with a mild or moderate degree of mental retardation. No side effects were observed. Because of its sedative effects and good tolerability, niaprazine can be used as a first-choice drug to improve behavior and sleep disorders in patients with autistic disorder. (J Child Neurol 1999;14:547-550).


Using single subject research design, we performed pilot research to evaluate the safety and efficacy of famotidine for the treatment of children with autistic spectrum disorders. We studied 9 Caucasian boys, 3.8-8.1 years old, with a DSM-IV diagnosis of a pervasive developmental disorder, living with their families, receiving no chronic medications, and without significant gastrointestinal symptoms. The dose of oral famotidine was 2 mg/kg/day (given in two divided doses); the maximum total daily dose was 100 mg. Using single-subject research analysis and medication given in a randomized, double-blind, placebo-controlled, cross-over design, 4 of 9 children randomized (44%) had evidence of behavioral improvement. Primary efficacy was based on data kept by primary caregivers, including a daily diary; daily visual analogue scales of affection, reciting, or aspects of social interaction; Aberrant Behavior Checklists (ABC, Aman); and Clinical Global Improvement scales. Children with marked stereotypy (meaningless, repetitive behaviors) did not respond. Our subjects did not have prominent gastrointestinal symptoms and endoscopy was not part of our protocol; thus, we cannot exclude the possibility that our subjects improved due to the effective treatment of asymptomatic esophagitis. The use of famotidine for the treatment of children with autistic spectrum disorders warrants further investigation.

Several important conclusions can be drawn based on a few hours of research on Google Scholar.
·         Your child may be subject to an allergic response that is outwardly hardly visible

·         The allergic response may be visible first as challenging autistic-like behaviour, rather than sneezing, runny nose, red eyes or wheezing

·         H1 antagonists can supress both the autistic-like behaviours and the typical allergic reactions

·         People do not all react the same way to H1 antagonist drugs.  A little experimentation is in order.  A drug that should work 24 hours can be effective for only 4 hours.

·         To avoid excessive use and possible side effects, allergists often combine different H1 antagonists, even though the information from the drug firm warns not to do this.

·         In some people the old H1 antagonists, that make you drowsy, work better than the new 2nd and 3rd generation drugs.

·         One old H1 antagonist called Ketotifen, seems to work wonders for some people.  It is both a mast cell stabilizer and a histamine receptor blocker.

I have ended up with a combination of Ketotifen and Claritin.  Claritin has an effect on behaviour within 20 minutes, Ketotifen had no apparent impact in the short term whatsoever.   You cannot keep giving Claritin every 4 hours.  It is supposed to be 10ml per day.
The day after taking Ketotifen things did change, and without having to overuse the Claritin.  The allergy is still mildly visible, but the challenging behaviours have gone.

I wish I had known about this last summer.  When Monty was aged 9, he went completely berserk on an aircraft and so as to restrain him, I was almost sitting on top of him, holding arms, legs and head; the flight attendant was asking if he would like a glass of water.  This year I will be well prepared with my Ketotifen/Claritin combo and anticipate no such problems.

Related Post:-

More on anti-histamines in Autism and introducing H4