Wasp or bee stings commonly cause significant swelling at the site of the sting, known as a local reaction. In adults, large local reactions may occur in up to a quarter of individuals. Although unpleasant, local reactions are relatively common and not in themselves serious.
In a minority of cases, an allergy to the venom contained in stings can trigger a more serious reaction (estimated 0.3-7.5% of adults). This may be nettle rash reaction (urticaria) or swelling (angioedema) separate from the sting site. A more severe allergic reaction causing problems with breathing or the blood circulation (anaphylaxis) can lead to collapse and is a medical emergency. Allergic reactions to bee stings are more common in beekeepers and their family members.
Someone who may have experienced an allergic reaction to a wasp or bee sting should always be referred to an allergy specialist for evaluation. An assessment will include allergy testing if indicated and identification of risk factors for further severe reactions. Patients with a confirmed allergy will normally be prescribed an adrenaline self injector for emergencies, with training provided to them or their carers in using the injector. For those who have experienced severe reactions a course of desensitisation treatment (also known as immunotherapy) may also be recommended.
Mosquito bites can also cause local allergic reactions, typically with an itchy bump that progresses to a larger red lump lasting a few days. Such reactions can be treated with antihistamine tablets or a steroid based-cream.