A majority of people get mild swelling and pain at the site of the sting, but patients with venom allergies can suffer anaphylaxis, which is a systemic allergic reaction that includes a combination of symptoms such as nausea, vomiting, dizziness, lightheadedness, cough, wheeze, trouble breathing, rash, hives, flushing, and/or swelling.
Bees, wasps, yellow jackets, hornets, and fire ants are all stinging insects in the order Hymenoptera whose venom can cause anaphylaxis in 0.5 to 3.3% of people in the US [Shaker et al. JACI April 2020].
Allergy testing via skin testing or blood work ordered by an allergist, in combination with a clinical history of systemic reaction to a sting, confirms a venom allergy. Venom skin testing is preferred over blood work, and involves using diluted amounts of stinging insect venom and doing a skin prick, which if negative is followed by subsequent increasing amounts of venom injected in small amounts under the first layer of skin. If at any point there is a wheal/flare response during this process, the test is considered positive for that venom allergy.