I react to bites by growing a half-boiled-egg swelling, with a really attractive yellow crust!!
Or I used to.
Now, at dusk, I apply 50% deet gel, and haven't been bitten for years, and I spend two months a year (June and September) in Calis.
I used to take cetirizine, which is about £1 from supermarkets for a 14 day supply, and douse the area in neat vodka!