First thing I do when I have a bite is swab the area with alcohol a few times a day.
Hydrogen peroxide or meat tenderizer are better. H2O2 WILL kill the bugs (better than alcohol), and the enzymes in the meat tenderizer will denature the toxic proteins of many insect venoms. Moiten a cotton ball with H2O2 and hold it on the affected spot for five minutes or so---repeat as needed.