Hi all. I was wondering if anyone else gets light headed when they take antihistamines? I was trying Claritin and was feeling lightheaded with one pill a day. When I saw that someone else bought the redi-tabs and split them in half, I tried that and I am still feeling the effect with a half dose. Is it that it's lowering my blood pressure ( which is already low)? something else? Will a different brand make a difference?
Leah
antihistamines and BP ( being light headed)?
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Hi Leah,
As far as I am aware, all antihistamines increase BP (at least for most people). Most brands typically increase my BP by anywhere from roughly 5 to maybe 15 points.
It seems to me that they sometimes increase the odds of experiencing a hypoglycemic effect. I had that effect last night, when I postponed eating supper for a few hours.
I suppose if you happened to be allergic to something in the anthhistamine it could cause a BP drop, but I'm guessing that's uncommon.
Maybe that's why I only took Claritin a couple of times and then switch to Allegra. 
I don't recall the details, I just remember that it didn't seem to work very well for me. Maybe it also causes memory loss.
If you should happen to be taking a monoamine oxidase inhibitor, (such as rasagaline), many/most atihistamines can trigger a BP spike, and that can cause some weird sensations that resemble light-headedness (been there, done that), but I doubt that you would be taking a drug in that class, because they're mostly prescribed to treat Parkinson's disease and related neurological issues.
Hopefully, someone else will be able to shed some light on this.
Tex
As far as I am aware, all antihistamines increase BP (at least for most people). Most brands typically increase my BP by anywhere from roughly 5 to maybe 15 points.
It seems to me that they sometimes increase the odds of experiencing a hypoglycemic effect. I had that effect last night, when I postponed eating supper for a few hours.
I suppose if you happened to be allergic to something in the anthhistamine it could cause a BP drop, but I'm guessing that's uncommon.
Maybe that's why I only took Claritin a couple of times and then switch to Allegra. I don't recall the details, I just remember that it didn't seem to work very well for me. Maybe it also causes memory loss. If you should happen to be taking a monoamine oxidase inhibitor, (such as rasagaline), many/most atihistamines can trigger a BP spike, and that can cause some weird sensations that resemble light-headedness (been there, done that), but I doubt that you would be taking a drug in that class, because they're mostly prescribed to treat Parkinson's disease and related neurological issues.
Hopefully, someone else will be able to shed some light on this.
Tex
It is suspected that some of the hardest material known to science can be found in the skulls of GI specialists who insist that diet has nothing to do with the treatment of microscopic colitis.
Thanks Tex. Maybe it is a hypoglycemic reaction and not a BP drop ( but it was happening to me in the morning AFTER breakfast) ????. I was thinking of trying Allegra next to see if it works better for me. The only other Rx I take is for thyroid and Singulair ( which I am going to ask if I can stop if I take an antihistamine). Do you take a full does every day?
Leah
Leah
Leah,
My BP is usually at a minimum that time of day. For example, this morning it was 95/53 when I checked it right after breakfast, even though I'm taking Allegra every morning ( I take all my pills immediately after breakfast). Maybe Allegra is an exception to the BP rule, because my BP certainly wasn't elevated this morning. Because of the low BP, today I have no energy, no strength, and no ambition. 
Tex
My BP is usually at a minimum that time of day. For example, this morning it was 95/53 when I checked it right after breakfast, even though I'm taking Allegra every morning ( I take all my pills immediately after breakfast). Maybe Allegra is an exception to the BP rule, because my BP certainly wasn't elevated this morning.
Because of the low BP, today I have no energy, no strength, and no ambition. Right now I'm taking a single 24-hour tablet every morning, because ragweed pollen levels are high. I've been taking it for 5 days now — I only take it when pollen levels are high. Taking it regularly, this way, I never have any hay fever symptoms, as long as I continue to take it.Leah wrote:Do you take a full does every day?
Tex
It is suspected that some of the hardest material known to science can be found in the skulls of GI specialists who insist that diet has nothing to do with the treatment of microscopic colitis.
Leah,
I felt spacey on half an Allegra, and the dry mouth was truly bothersome. I have low BP and I didn't notice BP drops per se, but I wonder if the antihistamine dehydrates you overall?
I bought some Claritin readi-tabs to try, but frankly, I'm wondering if i'll be happpier with a little D, instead of chasing the elusive norman in exchange for drymouth and brainfog?
I felt spacey on half an Allegra, and the dry mouth was truly bothersome. I have low BP and I didn't notice BP drops per se, but I wonder if the antihistamine dehydrates you overall?
I bought some Claritin readi-tabs to try, but frankly, I'm wondering if i'll be happpier with a little D, instead of chasing the elusive norman in exchange for drymouth and brainfog?
Leah,
When I was very sick with mast cell problems I had a big problem with lightheadedness and dizziness and it was unrelated to antihistamines. I also had BP abnormalities and I normally have BP in the normal range. So individuals with mast cell problems have POTS, or in my case hyperadrenergic POTS. Do you also notice tachycardia after eating or weakness in going from sitting to standing? Are you sure it is the antihistamine causing your symptoms? Does it go away when off of antihistamines?
Mary Beth
When I was very sick with mast cell problems I had a big problem with lightheadedness and dizziness and it was unrelated to antihistamines. I also had BP abnormalities and I normally have BP in the normal range. So individuals with mast cell problems have POTS, or in my case hyperadrenergic POTS. Do you also notice tachycardia after eating or weakness in going from sitting to standing? Are you sure it is the antihistamine causing your symptoms? Does it go away when off of antihistamines?
Mary Beth
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