system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: why does sour candy give you sores in your mouth?

I ate a bag of sour skittles on one side of my mouth earlier today and now my tongue is sore on that side. Why does this happen?
gpt
Acidic foods taste sour to us. So if you eat a lot of acidic food you literally damage the skin of your mouth via the acid.

Think of a lemon. Lemons are sour because they have a lot of "citric acid" in them.