Delayed Allergic Reaction to Insect Stings and Bites

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Delayed reaction to insect stings and bites

For most of us, wasp or bee stings (hymenoptera) are just a painful nuisance that we occasionally endure. The affected area will immediately react to the venom in the sting, typically causing local oedema (swelling), redness and itching. These reactions are due to our body’s defence mechanism against the venom and are largely due to the release of histamine at the attack site (for more information on histamine, see However, in some people who are allergic to insect stings, there can be an additional delayed and potentially deadly reaction. In the USA, approximately 50 people per year die of allergy to insect stings.


The hymenoptera include bees, ants and wasps and may number up to 300,000 species. Of particular interest to us from the perspective of stings that may generate an allergic reaction are: bees, wasps, hornets, yellow jackets and fire ants. If stung, most people will suffer relatively mild localised symptoms, but some people, who have been stung previously, may experience an allergic reaction when stung again. Allergies represent an over-reaction of the body to an agent which most of us would see as harmless. The reaction to subsequent stings gets progressively worse, unfortunately.

Allergy to stings and bites

If you are allergic to hymenoptera stings, you could suffer from an immediate allergic reaction, a delayed reaction, or both. The symptoms associated with an allergic reaction are varied and range from hives (urticaria), fever, itchiness, sore eyes, swollen glands and painful joints.

In some cases, an allergy suffer may go into anaphylaxis as a result of a sting – this might occur immediately or could be delayed; so if you know you are allergic to hymenoptera stings it would be sensible to get medical attention following a sting.

Anaphylaxis is rare, fortunately, but it can be fatal. The symptoms of an anaphylactic reaction may include difficulty in breathing; facial swelling or swelling in the affected limb; abdominal pain and shock. The first-line treatment is to administer adrenalin by injection, but urgent medical attention will be needed – the allergic response may cause the airways in the lung to constrict, making breathing very difficult.

Precautions and avoidance

If you know you are allergic to insect stings, you should discuss the possibility of carrying an emergency kit (epinephrine) with your doctor. The best advice is to avoid (if possible) situations and behaviour where you might get stung: never knowingly disturb an insect nest or colony, if you do, move away from it quickly; if an insect lands on you stay calm and brush it gently away; if picnicking, keep food covered until needed and take care when drinking soft drinks that no insects have got inside.

Additional Sources of Information