Antihistimines & CCSVI

[selkie]

I'm going to start again, because my original post has been so misunderstood, I don't know how to make the question any simpler than this:

Are anti-histimines harmful for people who have CCSVI? They seem potentially harmful because they restrict blood flow.

(Note: I'm not asking if vascular dilators are helpful - I'm only asking if anti-histimines are harmful?)

Sorry to be blunt, but my question either wasn't clear or continues to be misconstrued.