We give our 12 year old Culturelle x 2 a day. Before breakfast and with dinner. Like Gammaw, we have had difficultly with digestion when he is on an antibiotic. Working with the CF team, a dietician, and his regular Ped, we stumbled upon this and it has done wonders.
We have had no negative side effects, and since his stomach does not get upset he is in a better mood most of the time. Best of luck on this.
Jeff
Father of Parker Dx 2010 at age 10.