The allergies drive me crazy too and it seems that now that I'm pregnant are stronger! I remember taking Claritin a couple of times on my first pregnancy and now I have the healthiest baby ever! I'm 6 weeks pregnant now and I don't dare to take any allergie medication but I'm pretty sure you are safe if you do it very once in a while, only when you really need to.
To feel better doing it you definitely need to ask your doctor but I'll tell you something, when we don't know we are pregnant is when we do the craziest things like drinking or taking medication or things like that and 99% of times nothing happens.
Good luck and don't worry too much if one day you really need to take it ;)
Id consult your doctor before taking anything. My doctor gave me a list of medications i could take. For allergies....benadryl, sudafed, and something else was on it. I dont remeber what it was though
I asked my doctor about claritin cause I suffer from allergies badly and she said it's fine to take. I take one every night and have had no problems. I'd call the doctor and find out to be on the safe side....everybody is different.