Horsefly bites are nasty and the local swelling and redness
you are experiencing is quite normal. The venoms 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.
10mg 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.