Am i suppose to stay away from orangejuice completely while taking allegra (fexofenadine) d? if so, can i take a vitamin c supplement?

Allegra (fexofenadine): Not completely, but i would avoid oj for 2 hours before or after taking allegra (fexofenadine). It is safe to take vit c. It is the acid in the oj that inactivates allegra (fexofenadine). Since i assume the oj is a breakfast item, you could always jut take the Allegra (fexofenadine) before bed.

No and Yes: A new type of interaction in which fruit juices diminish drug bioavailability occurs through inhibition of drug uptake by inhibiting the transport from the GI tract into the blood. It seems to be less of an issue with acid and more of a receptor/transport. The inhibition lasts not more than 4 hours. A vitamin c supplement would be ok, but just change the time you drink your oj and take allegra (fexofenadine).