Quad sets. 1  Sit with your leg straight and supported on the floor or a firm bed. (If you feel discomfort in the front or back of your knee, place a small towel roll under your knee.) 2  Tighten the muscles on top of your thigh by pressing the back of your knee flat down to the floor.
allergic reaction. allergic reaction in Medicine. allergic reaction n. A local or generalized reaction of an organism to internal or external contact with a specific allergen to which the organism has been previously sensitized. Examples from the Web for allergic reaction.
Anaphylaxis is a severe, sometimes life-threatening, allergic reaction that occurs within minutes to several hours of exposure an allergy-causing substance (allergen). Anaphylaxis also is called anaphylactic shock.