A sting from a honey bee, hornet, paper wasp, yellow jacket, or fire ant causes a painful reaction in the unfortunate recipient of the attack. These stinging insects belong to the Order Hymenoptera. The venom of these insects contains substances that cause pain, redness and swelling at the site of the sting. The venom can also cause an allergic reaction in some individuals. Less than 5 percent of people are allergic to insect stings, but the reactions can be severe and life-threatening.

Stinging Insects

While the sting of any insect is likely to be unpleasant, the venom from social bees and wasps, i.e. hive-dwellers, pose a greater medical risk. Female worker bees and wasps possess venom and a stinger that acts like a needle to inject the venom into other organisms they perceive as a threat. Stinging is a defense mechanism to protect the hive. Solitary bees and wasps, such as carpenter bees and mud daubers, can inflict painful stings but the venom only causes pain for a few minutes and does not contain allergens that would cause an allergic reaction.

Immune Response

Individuals stung for the first time do not experience an allergic reaction. It takes one or more stings to kick off the immune response that leads to an allergic reaction. The initial sting sensitizes the person to the allergens in the venom. Sensitization occurs when the immune system creates antibodies for a specific allergen. These anitbodies attach to mast cells found in connective tissue throughout the body. There are multiple binding sites for the anitbodies on each mast cell. The more binding sites on these cells indicates a more severe allergy. Once a person is sensitized to the venom of a particular stinging insect, future stings can cause an allergic reaction.

Cross-Reactivity

Some people may also experience an allergic reaction to the sting of an insect they weren't previously sensitized to if it is closely related to the insect that first induced their. This allergic reaction to another stinging insect is called cross-reactivity. Closely related insects may produce the same or similar allergens that can induce the same type of immune response in an allergic individual. For example, a person allergic to hornets may also experience an allergic reaction from a yellow jacket sting because of the similarities in their venom. However, this person would probably not be allergic to honey bee venom, because they are not as closely related to hornets. Conversely, a person allergic to honey bee stings may also be allergic to bumblebee stings because those insects are closely related and produce similar allergens.

Signs and Symptoms

Common allergic reactions to insect venom include swelling beyond the site of the sting, itching, hives and facial redness. Approximately 40-50 people per year die from venom-induced anaphylaxis: a systemic allergic reaction that causes a sudden drop in blood pressure can lead to cardiac arrest. Other serious symptoms include nausea, vomiting and difficulty breathing. Many people who are allergic to insect stings are also allergic to other common allergens, such as peanuts, shellfish, dust mites, penicillin and pollen. Allergy patients who are unsure if they have a stinging insect allergy should get tested for the presence of those antibodies associated with insect venom.