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Those Who Benefit From An Antihistamine

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reading through this forum it seems as if many people with POTS here benefit from taking an antihistamine (like zyrtec for example). I am very interested in finding out if all of you who benefit from an H1 or H2 Blocker have an "official" Diagnosis besides POTS , for example: MCAD, Allergies, Histamine Intolerance or anything else that would make your doctor prescribe you an Antihistamine. Iam asking because i do benefit from taking zyrtec but i dont know exactly why? Do i need to find out why? My doctor doesnt seem to worry and has no idea were else to send me to find out why i respond to the zyrtec. We both think its probably due to an Histamine Intolerance that showed itself 2 weeks ago when i ate "bad" prawns, but who knows? Do you all know why you benefit from Antihistamines?

Thanks a lot (and sorry that i have so many questions lately, iam still learning :-)). carinara

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MCAD for me, which manifests as chronic hives, flushing, severe autonomic symptoms (low BP, tachy, pooling), chest & throat tightness, trouble breathing, etc. With the H-1's, H-2, and singulair, I'm greatly improved.

Others also benefit from antihistamines to control allergies/asthma. The better controlled they are, the easier it is to control autonomic symptoms.

Hope you feel better & figure things out.


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allergies and/or histamine is part of my problem, but I don't think all of it. I've had allergies my whole life, before pots. but there was a period several years ago when i was reacting allergically to EVERYTHING and it was also having wild ans reactions. (knock on wood) my allergies are less extreme now, and my pots is 80% managed. I take allegra, singulair, and nasonex daily, with benadryl for breakthrough allergies, in addition to midodrine and florinef specifically for the ans issues. one doc said that he thought some of the allergy stuff is ans related, as our bodies "overreact" to many things.

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I don't have known allergies yet I've felt better with Claritin-D, Zyrtec-D, Alka-seltzer Cold, Claritin, etc. One thing to keep in mind, the decongestant combined with the anti-histamine is usually either pseudoeffedrine or phenylephrine (now that meth laws complicate pseudo).

Pseudoeffedrine triggers norepinephrine which is vasoconstrictive. So does phenylephrine reportedly. So for me, it's like a my poor man's midodrine... but it has more side effects since it is less "selective" meaning it hits adrenergic receptors elsewhere in the body besides vascular smooth muscles. In my case, that's ok because I tend to be bradycardic and can use a little speeding of the heart (except when I stand up and go tachycardic, of course). For others this can be touchy. I do get more palpy but kind of put up with it.

That is a non-histamine explanation for some benefit... but I also have the sense that the anti-histamine helps me too, even though I lack known condition along those lines! I've been trying straight pseudoeffedrine too (Sudafed) to get a handle on how much each component is factoring in to the benefit. So hard to say... but I do think the anti-histamine and pseudoeffedrine induced norepinephrine BOTH help me modestly!

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  • 1 year later...

i developed ulcerative colitis about 10 years ago. along with the UC, i began to have numerous food allergies (fish, shellfish, wine, pineapple, strawberries, avocado, nuts, etc.) and reacted also to seasonal allergens. throughout this time i was having low-level POTS symptoms but didn't know what they were: mostly periods where my nose would get stuffy, my heart would race, and i'd have odd fluctuations of body temperature. i figured it was asthma, since my lungs were often affected. in the last 3 years or so, i started to have hyperadrenergic symptoms, like blood pressure spikes, but again, i didn't see the connection. i figured it was anxiety, although the source of it was mysterious.

well, just a few months ago these symptoms started getting bad enough that i did some reading, and all signs pointed to hyperadrenergic POTS. i noted the connection to mast cell activation, and given my history of food allergies i decided to try a low histamine diet. so far, it seems to be helping a lot. when i deviate from the diet, i start to get "potsy" again, which includes a rise in temperature around my head and neck, but no increase in measured body temperature with a thermometer. it's like that heat (inflammation) is confined to my CNS. then my pulse and BP rise, which seems like orthostatic intolerance kicking in, and trouble with baroreceptors malfunctioning and too much adrenaline.

like some here, i've experimented with taking antihistamines, like benadryl or zyrtec. both seem to work. but i get even better relief from large doses of buffered vitamin c, which is a potent antihistamine.

when people here mention H2 blockers, are you referring to an antacid, like tagamet? if so, how does that seem to work for you, and how/when do you take it in relation to your meals? thanks!

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