system
Given the following post, respond as if you're commenting on Reddit:
human
[ELI5] Why can we gain resistances to medicine, alcohol, poison, etc. but not so much for allergies or pollutants?
gpt
We can gain resistance to allergies. Many people are allergic to cats but they own a cat which they become less allergic to.

Allergy shots work in a similar way by helping your body get used to the allergen. Since it is not a harmful foreign body your immune system learns that it's not dangerous over time.