Should i take benadryl (diphenhydramine) until my zyrtec really kicks in?

Probably not helpful: Both drugs need to be absorbed by the GI system before they take effect to stop itching and sneezing (can take up to 1 hr). Benadryl (diphenhydramine) can dry up mucus (and make you sleepy), which zyrtec will not do at any time. If you have taken zyrtec for several days without relief from itching or sneezing, you may have something besides allergies (e.g. A cold) or need a different treatment. See your doctor.