Has anyone tried taking Zyrtec for morning sickness? My doc suggested it and I tried it this morning and it actually helped...until about 4 hours after taking it I got diarrhea. I took 3 activated charcoal capsules and that cleared the diarrhea up. I just want to know if anyone else has experienced this side effect and if so how long it lasted. I don't want to keep taking it if it's going to cause diarrhea.