<s>[INST] i have had a severe reaction to wat we believe are horsefly bites so swollen hard hot big area around bites on arm and chest my arm is in alot of pain as is my chest have had antihistamine administed at A&E and all day i suffer from anaphalaxia wen stung by bees wasps and peanut allergy is the severe pain im experiencing down thru my arm into my hand normal [/INST] Hello, Horsefly bites are nasty and the local swelling and redness you are experiencing is quite normal. The venom between horsefly, bees and wasps do differ and therefore not everyone gets anaphylaxis to horsefly stings even if they are allergic to bees and wasps. Antihistamines (cetirizine 10 mg twice daily) for a week and local application of a mild steroid cream will help. If the area is infected, you will need a course of antibiotics something like flucloxacillin. Thanks. </s>