How often can I take reactine extra strength allergy pill?

Generic Zyrtec (cetirizine) Reactine is a generic form of zyrtec (cetirizine). It is dosed once every 24 hours unless your doctor recommends higher doses for specific conditions.
Once a day. I believe you are referring to one of the generic Cetirizine products. There are so many names for this medication depending on the store where you purchased it. Cetirizine is a once a day medication.