Ricardo,
Interesting comments... You're very correct in suspecting Benadryl has other physiological effects on CH beyond blocking histamine receptors. Benadryl also acts as an SSRI... and likely a lot more...
Moreover, there's a complex set of neurological reactions that take place during allergic reactions in the nose, airways, gut and skin that produce histamines that further trigger neurogenic inflammation and the release of inflammatory neuromediators...
The list of neuromediators released from nerve cells when insulted by an allergic reaction has some very familiar culprits also found elevated during the pain phase of CH including: Calcitonin gene-related peptide (CGRP), Vasoactive intestinal peptide (VIP), Neuropeptide Y (NPY), and Tachykinins (substance P, neurokinin A and neurokinin B).
There's a fascinating paper on all this titled "Neurogenic inflammation and allergy" at the following link:
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My original intent in taking Benadryl (Diphenhydramine) was merely to stop a very obvious allergic reaction to alder pollen...
I grew up on this property and lived here until I joined the Navy in 1965 to start flight training. I'd never experienced any allergies while living here with the exception of a bee sting at age six. This spring was quite different and the pollen much heavier.
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My response to Benadryl was two-fold. It stopped/suppressed the obvious allergy symptoms and I was also very pleased that it also stopped the burn through CH hits that started with the heavy pollen fall.
I'd titrated up to 50,000 IU/day vitamin D3 and bumped the magnesium up to 800 mg/day, but was still getting hit until I started the Benadryl. The CH hits stopped in less than 12 hours after an initial dose of 50 mg Benadryl.
I conducted my obligatory check for causation a few days later by stopping the Benadryl and was greeted by a resumption of CH hits within 12 hours.
All this got me thinking there's a far greater relationship between allergic reactions and CH than covered in prevailing CH literature. Moreover, none of the Standards of Care recommended CH medications address allergies... That makes allergies the elephant in the room for neurologists and headache specialists treating CH'ers.
I'm also firmly convinced there are obvious dose-response relationships in play with both vitamin D3 and Benadryl with respect to a cessation of CH symptoms with an allergic reaction present.
During the heaviest alder pollen fall, I needed 100 mg/day Benadryl and at least 50,000 IU/day vitamin D3 to remain CH pain free. Any dose of Benadryl less than 100 mg/day or vitamin D3 less than 50,000 IU/day resulted in a resumption of CH attacks.
I bounced all this off Dr. Todd Rozen M.D. who heads the Headache Center at Geisinger Healthcare, Wilkes-Barre, PA. He was genuinely interested. He offered that he frequently administers a Benadryl IV along with other CH medications on CH patients admitted for severe refractive CH... but had never suggested oral Benadryl as an adjunct to other CH preventatives.
I've updated the anti-inflammatory treatment protocol for CH with a new section on allergies and Benadryl.
Thanks again for your comments.
Take care,
V/R, Batch