According to WedMD, an allergic reaction can make an individual feel tired or ill, and severe allergic reactions can even leave a person incapacitated. Other severe symptoms of an allergic reaction include itching, hives, wheezing, tightness in the throat, and tingling in the hands and feet.
An allergic reaction occurs when a person has an abnormal reaction to an otherwise non-harmful substance in the environment. The substance that the individual has a reaction to is referred to as an allergen. Examples of allergens include pet dander, pollen, mold and dust. Allergies are usually treated with prescriptions, shots or over-the-counter medications.