People experience an allergic reaction to bee stings because their immune systems have become sensitized to the venom, explains MedlinePlus After being exposed once to a specific substance like bee venom, some people's immune systems cause an allergic reaction if they're exposed to it again.
Allergies are the result of the immune system's response to particular substances, such as pet dander, pollen and bee venom, says Mayo Clinic. Antibodies are part of the immune system's protection from invaders that cause infection or illness. Allergies occur when antibodies identify an allergen as harmful even when it's not. Contact with an allergen causes an inflammatory reaction that can affect sinuses, skin, airways and the digestive system. The severity of a reaction differs from person to person and can range from mild irritation to a life-threatening reaction called anaphylaxis, as stated by WebMD.
Most people are not allergic to insect stings and may misinterpret a normal reaction as an allergic reaction, notes WebMD. Stings cause three types of reactions: normal, localized and allergic. A normal reaction is characterized by redness at the sting site, swelling and pain, while a localized reaction results in swelling that extends beyond the site but is usually no more serious than a normal reaction. An allergic reaction may cause dizziness, rapid pulse, wheezing or swallowing difficulties, labored breathing, or restlessness and anxiety. Other signs include swelling of face, throat or nose tissue, and hives that appear as a rash and spread beyond the sting.