system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: why does my body tell me to scratch, when it basically worsens absolutely everything? (Scabs, rashes, bug bites, pox, poison ivy)
gpt
Typically it is due to a natural response by your immune system to foreign material. Say you had a tick or leech attached to your skin, scratching would make sense. However, your body doesn't immediately recognize the difference between a tick vs a mosquito, so in either case you get this immediate immune response that is very general referred to as **inflammation**. 

Inflammation involves an early stereotypical response, one of which includes the release of histamines which causes itching, particularly when released in the skin. Depending on the actual foreign material, it can take the body some time to realize exactly what is going on and for the correct immunological response to take over. In some case this the immune system never specializes enough to stop the itching and the foreign material must be completely removed first. In a worst case scenario, the immune system responds without stimuli and the itching never goes away.