Larken,
YES! I think so and I have become allergic to atarax and zyrtec after taking it for a year! I asked my doc if is possible to become allergic to cromolyn.  He said yes, it is plant based and possible.  He told me to help prevent this from happening, not to skip any doses of the cromolyn.  So I am very serious about not skipping because there are tons of antihistamines but not tons of mast cell stablizers!!  I have even started rotating my meds, I told the doc about that and he said that wouldn't really help, either you are allergic to them or you are not.

If you feel your body is becoming used to your meds be sure to choose an emergency med that you don't take on a regular basis.  That way it will always work for you!
Pam

For me, I switched from zantac to pepcid (generic).  I have been using claritin instead of zyrtek.  My specialist wrote me a script for clarinex, I got it filled but haven't tried it yet. It is pretty expensive, so I only had them fill half the script.  It is a blue pill, so I am thinking it may be a trouble maker!  When I do take it, he told me to take it instead of the claritin, must be a stronger dose?! Doc said I could continue my allegra with it.  However for some reason, allegra makes me feel unwell and I find myself not wanting to take it...can't put my finger on it.  But I usually take benedryl in place of the allegra.  
I plan on switching back to the zantac at some point, I just think that if you can have a rotating diet to prevent allergies that rotating meds(that you know you can take) couldn't hurt.  Doc said it didn't matter, but I say It cant hurt!  I am hoping that it will let me find the perfect med combination.  Plus I change one at a time.  
I feel like my body has a way of figuring out how to be allegic to what ever I give it for an extended amount of time....Maybe I am paranoid, but at least in my mind I will be able to continue to take meds longer.
Good example: I bought a bottle of Target sleep aids(benedrly), because they are blue instead of the pink benedryl.  I know that I can't take the pink ones because of the dye.  So I have taking this bottle 6 months or so.  It is a big bottle, but the other night I took one pill and my feet started to itch!  It is driving me crazy- six months ago I could take the blue dye, but now it is making me react.  So I bought some dye free, however they are in gelatin capsuls and gelatin is high in sals, sulfates, and I think histamines.  But they seem doable maybe a little reactive, but I'm guessing in six months those will not work.  So I'm going to do my best not to use them and save them for emergencies!
I need to find the liquid, dye free benedryl. I can't find it anywhere.  I thought it was on the market but maybe not!?
Sorry to ramble on!  I'm just wish this could be easier!
For you maybe you could just add an extra dose of one of your h1's, but talking to the doc would be the best thing to do.  Just don't let him tell you that it is impossible that its in your mind...because it is not!
Pam

Thanks Kat!!!!
There is a Target 2 miles from my house!!!
Yea!
Pam

I will let you know if I find it!!!!

I'm feeling weird from Target children's dye free Benadryl too. I was using Wagreens c df Ben but ran out. I'm going to try it again tho. I like having a liquid on hand.

Btw. Doozly just gave us a lot of good info on med ingredients on my intro thread. Just ignore my ramblings. Lol ..

I'm finding that some times I can add a known allergen back into my diet and sometimes I can't.  It seems to depend on how strong my reaction is.

And sometimes I'm adding too much of the known allergen and that's what's nailing me.  Tracking all this is such a pain. Tc .. Marcia

I agree with Joan.  Marcia, you should minimize all of your triggers until you become stable, I have been working on this a year now! I am just now adding/testing things.
I did read the good info about the Target dye free benedry, I wish I had read it a day earlier, I wouldn't have wasted $5.50! I am way to sensitive to have all those extra inactive ingredients, even after I have stablized!
I read the box at the store, should have gone with my gut and just put it back!

The only way to know is to have it compounded or have preservative/additive-free Benadryl injected.  I don't know if an allergist can do a skin test for Benadryl, but I would think so.  Still, they'd have to have additive-free in order to get an accurate test.

Benadryl can definitely cause a drugged or sleepy feeling.  I wonder if hydroxyzine (Atarax) would do the same.  I don't know the additives in that either, though.

Benedryl is marketed as a sleep aid, BECAUSE it is sedating!!
Atarax was sedating for me. I loved it, because I slept so well!