Irreconcilable differences

I was excited to find two new products at Costco: an OTC Allegra two-pack and ultra-delicious red grapefruit sections in convenient take-along cups.  Unfortunately, I soon discovered that the two are incompatible since grapefruit (and other citrus juices) cut the effectiveness of Allegra in half.  My solution? Have the grapefruit for breakfast; take the Allegra in mid-afternoon.  So far, so good...but the pollen assault is just beginning.