Sherrine's friend using Claritin and zantac some food for thought. Claritin is an H1 blocker. It blocks H1 histamine receptors. Zantac/ranitidine is an H2 receptor blocker. There are even more different histamine receptors, but those 2 have meds available to block them. It sounds very much as though this person has headaches induced by mediators released from mast cells.
These meds take up positions on the histamine receptors of mast cells, also, and stop the cascade of histamine from one mast cell triggering another and another and then another mast cell is activated, and so on.
There is one H2 blocker to watch out for, and I learned this from a mistake Rockon made in choosing it, finding it not helpful, reading about
it, and returning to ranitidine as her H2. (I have permission to share this information.)
Her post about
the other H2 (blocker/antagonist), The following is all quotes:
Cimetidine, a histamine2 (H2) receptor blocker, lowers DAO (which is to say it's inhibitory), so it should only be used if no others in this class works for you. Diamine oxidase (DAO) is the main enzyme involved in histamine metabolism (breakdown).
"....Antihistamines had no influence on diamine oxidase activity except for cimetidine, which caused 25% inhibition at the highest dose tested (p < 0.0002) (positive control: aminoguanidine 85% inhibition (p < 0.0001), dihydralazine 68% inhibition (p < 0.0001)) and diphenhydramine, which caused 19% increase (p < 0.0001) of enzyme activity.
Conclusion: Serum diamine oxidase levels do not show daily variations allowing assessment anytime during office hours. However, diagnostic interpretation of serum diamine oxidase levels may be difficult."
DAILY VARIATIONS OF SERUM DIAMINE OXIDASE AND THE INFLUENCE OF H1 AND H2 BLOCKERS : A CRITICAL APPROACH TO ROUTINE DIAMINE OXIDASE ASSESSMENThttps://scinapse.io/papers/1979166839
~~ ~~ ~~ ~~ ~~
In vitro study. 1988.
"...These results have allowed the selection of cimetidine, an H2-antagonist but also an immunomodulating compound, as inhibitor of these two enzymes. Cimetidine is an uncompetitive inhibitor of ALP (Ki = 3.2 · 10−3 M at pH 10.5), and a good inhibitor of DAO...
Comparative inhibition of human alkaline phosphatase and diamine oxidase by bromo-levamisole, cimetidine and various derivativeshttps://www.sciencedirect.com/science/article/abs/pii/0006295288906053
pretty sure I have a virus in the sinuses making them so nutty right now, but I tried a couple of cimetidine yesterday, to see if it was a good H2 for me, and now I know that can't have been helpful.