Concomitant reactions are reactions that occur only when another allergen, such as pollen, dust or mold, is present.  An example is milk sensitivity or a mint sensitivity that occurs only when ragweed pollen is present.  Concomitant reactions can occur up to six weeks after a pollen season is over.  Another example of a concomitant reaction is prescription drugs provoking reactions to normally "safe" foods.  A few of the many other concomitant reactions that can occur are to legumes and grains when any grass pollen is present; to milk, mint, onion, chocolate and nuts when a viral infection is present; and to lettuce when cottonwood pollen is present.