Signs and Symptoms of Allergies

Many allergens such as dust or pollen, are airborne particles. In these cases, symptoms occur in areas in contact with air, such as eyes, nose and lungs. For example, the causes of allergic rhinitis, also known as hay fever, irritation of the nose, sneezing and itching and redness of the eyes. [3] Inhaled allergens can also cause asthma symptoms, caused by narrowing of the airways (bronchoconstriction) and increased production of mucus in the lungs, shortness of breath (dyspnea), coughing and wheezing.

Apart from these ambient allergens, allergic reactions caused by food, insect stings, and reactions to medications such as aspirin and antibiotics such as penicillin. Symptoms of food allergy include abdominal pain, bloating, vomiting, diarrhea, skin rashes, and swelling of the skin during hives. Food allergies rarely cause respiratory (asthma) reactions, or rhinitis.

Insect stings, antibiotics and certain drugs produce a systemic allergic reaction, also called anaphylaxis, many organs may be affected including the digestive system, respiratory, and circulatory system. Depending on the number of severity, may cause skin reactions, bronchoconstriction, edema, hypotension, coma and death. This type of reaction can be triggered suddenly or the onset may be delayed. The severity of this type of allergic reaction often requires injections of epinephrine, sometimes through a device known as EpiPen or Twinject.

The nature of anaphylaxis is such that the reaction may seem to disappear, but may recur over a period of time.

Substances that come into contact with the skin, such as latex, are also a common cause of allergic reaction known as contact dermatitis or allergic eczema. Skin often cause a skin rash or swelling and inflammation of the skin, what is called "wheal and flare" reaction characteristic of hives and angioedema.