BAsic information description A life-threatening allergic response to drugs or any other allergy-causing substance. Reactions that happen the fastest are often the worst. frequent signs and symptoms Any of the following can happen in seconds or a few minutes after being exposed to something that you are very allergic to: Tingling or numbness around the mouth. Sneezing, coughing, or wheezing. Swelling around the face or hands. Feeling of anxiousness. Weak, rapid pulse. ...