I take prilosec and zyrtec (cetirizine) d on a daily basis. would creatine mixed with these have any additional effects on my health/body?

Not Likely: I do not like to give patients Zyrtec-D on a regular basis because the pseudoephedrine in it can cause increased heart rate, blood pressure, insomnia, irritability, and agitation. Prilosec can cause some vitamins and minerals not to absorb into the body from the digestive tract as easily so if you are seriously working out you might discuss this with your doc. These don't interact with creatine.