Hey Amanda,

Thanks for the update on your friend.  I'm happy to hear the antihistamine was effective in jump starting vitamin D3's capacity to prevent CH.  I won't go into the biochemical explanation why or how this works... as you already know it works, that's the important part.

Cycle length while taking the anti-inflammatory regimen and how long to stay on the antihistamine are two good question. 

There's no real trend on cycle length for episodic CHers taking this regimen.  Some report a significantly shorter cycle and others say it lasted two weeks longer...  so it's basically a wash.  No real statistically significant trend.

A week to 10 days treatment with a first-generation antihistamine should be sufficient to enable vitamin D3 to exert and maintain it's CH preventative properties. 

That said, a week to 10 days is just a number...  If the CH return when your friend stops taking the antihistamine, just restart it and continue for another week to 10 days. 

There's really nothing wrong taking a first generation antihistamine for 6 to 8 weeks of an episodic cycle as long as you're not walking around like a zombie, half asleep in a constant fog...  If that's the case, cut the dose or space out the doses to a tablet every 7 to 8 hours and right before bed.

Regarding the vitamin K2 (MK4 and MK7).  You can order this over the Internet from iherb.com.  I order Super K with Advanced K2 Complex at the link below:

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Take care and please keep us posted.

V/R, Batch