If someone is allergic, too much histamine can cause anaphylactic shock, a reaction characterized by difficulty breathing, dizziness, a drop in blood pressure, and even cardiac arrest. My mother's foot nipper was most likely a blood-sucking bug, so no venom was injected and her reaction to the bite will be no more than an itchy bump. The bite of a parasitic arthropod, which feeds on blood and includes the bedbug, mosquito, midge and black fly, triggers a histamine release, which produces the pale white bump surrounded by a reddish flare. The bump may itch, but the reaction usually disappears in a few hours as the irritant dissipates in the tissue and histamine levels fall. It's usually gone altogether within three days.
Some parasitic arthropods can trigger a more severe reaction.
A mosquito, for example, has saliva that contains a protein to keep the blood from clotting and cutting off its gory meal. Some people who have been bitten by a mosquito develop a type of antigen that, when a subsequent bite occurs, triggers the growth of an increasingly itchy, inflamed bump that can harden and take two to three weeks to disappear. The most effective are the hydrocortisone and antihistamine medications, which penetrate the skin and block the production of histamine. For my mother, only time will tell if it will fade quickly or if she'll still be scratching a week from now. Either way, this nip shores up our fear of fanged sheet-dwellers.