system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why does scratching a bug bite feel so good?
gpt
Most "ichy" bug bites are a result of a substance the bug injects into the body that causes an allergy like reaction. For mosquitos, their spit contains histamines, a common irratant. Scratching feels good because it releaves that itch (temporarily) by basically distracting the nerves with a subtle pain signal. But avoid scratching as much as possible, because it can worsen the bite and lead to infection.