These allergens include medication, plants, pollens, animals, insect bites, food, exercise and, even, changes in temperature. Hay fever is one of the most common allergies. The cause of an allergy can be hard to determine at times. You can often discover the cause by noting when the symptoms occur. Symptoms that develop the same time each year are often due to grass, weed or tree pollen.
Allergies also seem to run in families - parents with hay fever often have children with allergies.
Individuals having an allergic reaction can have one or all of the above symptoms, and they can range from mild to very severe. A few people with severe allergies to insect bites and to certain foods and drugs, can develop anaphylactic shock. This is a sudden, severe reaction that may cause breathing problems and a drop in blood pressure. Other symptoms seen with anaphylactic shock are hives, swelling, throat tightness, difficulty swallowing, and pale, cool skin. Prompt care is needed for this medical emergency as it is life-threatening.