Sneezing, red, swollen itchy eyes, nasal congestion, wheezing, hives (red raised patches on the skin) and rashes are signs you may be dealing with allergies.
Seasonal allergies to grass, weed, and tree pollen and molds may come and go with the seasons. Cat and dog dander (the shed skin cells of pets) are another common cause of allergies. Food allergies to peanuts or milk can cause cramps, vomiting, and diarrhea. Anaphylaxis is an allergic reaction with hives/itching all over, wheezing or shortness of breath, hoarseness or tightness in the throat, and/or tingling in the hands/feet/lips/scalp. Anaphylactic reactions are life threatening and need immediate medical help.
All allergies are produced by the body overreacting to a harmless substance (allergen). Once exposed to an allergen the body begins to produce specific antibodies against it. These antibodies activate mast cells which are located throughout the body with some higher concentrations in the airways, intestines, skin and elsewhere. These cells release histamine (along with some other chemicals) which causes most of the symptoms of an allergic reaction.