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 life-threatening type of allergic reaction. Anaphylaxis is a severe, whole-body allergic reaction to a chemical that has become an allergen. An allergen is a substance that can cause an allergic reaction. After being exposed to a substance such as bee sting venom, the person's immune system becomes sensitized to it. When the person is exposed to that allergen again, an allergic reaction may occur. Anaphylaxis happens quickly after the exposure.