Zyrtec is gdod stuff for allergies. It shouldn't affect your training at all. If it were me, I would only take it when you thought allergies were coming on, and not every night. That way you save them longer, don't build up a tolerance as fast, and sometimes one pill clears me up for a week or two. I don't have allergies anymore from sinus flushes and liver cleanse's, but if I did, I would take zyrtec or allegra.