Allergies are one of the most common ailments that occur throughout the United States each year. The Centers for Disease Control and Prevention estimates that in 2006 alone, 13.1 million people visited physicians offices, hospitals and emergency departments because of the effects of one form of allergic reaction called allergic rhinitis. When your body comes into contact with a potential allergen, it can react physically in several ways.
Skin
An allergic reaction can present itself on the skin, especially in cases involving contact dermatitis. Most commonly, this sign presents itself as hives or a rash. Hives and rashes occur as the body produces histamine as a response to contact with an allergen. Histamine can cause blood to leak from the small blood vessels near the skin's surface, resulting in redness, small bumps or rash.
Angiodema
Inflammation is another common physical effect of allergies, especially a form of inflammation known as angiodema. Angiodema consists of swelling that occurs deep within the tissue of your skin. This can result in the severe swelling of hands, feet, cheeks and the areas around the eyes. Like hives, swelling occurs as a side effect of mast cells releasing histamine into the skin and bloodstream in reaction to an allergen. Not all allergic reactions involve angiodema. Your risks for developing this reaction are often connected to heredity and family history, as well as other disorders such as lupus, lymphoma or thyroid disease, states the Mayo Clinic.
Itching
Itching can stem from the release of histamine in an allergen-affected area of the skin. As skin tissue comes into contact with histamine, afferent sensory neurons are activated, which send a signal from the skin to the central nervous system. Once this signal reaches the brain, the body reacts by inducing the sensation of an itch. Depending on how bad the allergic reaction is, the itch may be mild, or may be so intense that the skin becomes damaged from scratching.
Rhinitis
Rhinitis occurs when the mucous membranes of your nasal cavity become inflamed. More commonly known as a runny nose, rhinitis causes an excess production of mucus in order to remove an irritant or allergen from the nasal cavity. Mucus production increases because of the release of histamine. This may result in nasal congestion, sneezing, teary eyes and post-nasal drip.
Anaphylaxis
Anaphylaxis is the most severe allergic reaction that can occur with allergies, but is also rare, states the National Jewish Health organization. Anaphylaxis occurs when an allergen affects the entire body, and can occur from allergens ranging from prescription medications to bug bites or stings. The physical signs of anaphylaxis can include difficulty breathing, swelling of the mouth and throat, dizziness, fainting, vomiting, diarrhea and stomach cramps. Many of these side effects can become life-threatening if not treated immediately. The most common treatment for those going into anaphylaxis is a shot of epinephrine.
