Allergies to insect stings

The most common allergic reactions occur with stings from bees, wasps and ants. The degree of allergy varies widely and most people experiencing only mild symptoms such as local itching and minor swelling are not considered ‘allergic’ to insect bites. Other people, though, may have severe allergic reactions when stung, with some people experiencing a life-threatening condition known as anaphylaxis. Most stings tend to occur in summer.

Discomfort and pain at sting site

The majority of insect stings only cause discomfort and result in local pain, itching, some swelling and redness at the site of the sting, and this is not considered an allergic reaction. Local treatment is generally all that is needed to treat this type of sting. In these cases, the area should be washed and disinfected, and ice applied to relieve the swelling and general discomfort.

In cases where the swelling continues to expand, antihistamine or possibly steroid treatment may be needed. On rare occasions, the sting site may become infected and antibiotics may be required to treat the infection.

What is an allergic reaction?

The severity of allergic reactions varies from person to person. Most allergic reactions are minor, and cause only local swelling and itching. Anaphylaxis is a severe form of allergic reaction, which can be fatal. It involves swelling of the airways, difficulty breathing and a drop in blood pressure. Anaphylaxis can also occur following exposure to a number of other triggers, such as certain foods or medicines, as well as insect stings.

Signs of allergic reaction include:

• rash and intense itching in areas other than the sting site;
• puffy eyelids;
• wheezing and difficulty in breathing;
• difficulty in swallowing due to swelling of the tongue, and hoarseness; and
• dizziness and fainting - this is a very serious reaction.

Severe allergic reactions generally occur within minutes of the sting, but may occur up to 24 hours after the sting. Cases of severe allergic reaction are a medical emergency and require immediate medical treatment.

Treatment of insect allergies

If stung by a bee or a wasp, do not pull or squeeze the sting that is left in the skin as this can cause more venom to be released. The sting should be removed by scraping it sideways with a fingernail, blunt knife or similar object.

Allergic reactions need to be treated with adrenaline. There are self-injectable devices available for people with known reactions (eg EpiPen, Anapen). These devices are already filled with adrenaline and should be injected into the muscle at the front of the thigh. People with known anaphylactic reactions, whether to insect stings, certain foods or other triggers, are advised to carry the device at all times. These types of device hold only one dose, and people should be taken to hospital after the adrenaline shot - in case they need further doses and for specialist observation.

See also the Action plan for insect allergy

Original material provided by myDr, 2007. Reviewed by everybody, January 2012.