system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5 Allergies: Why does exposure from allergy shots make you less senstive, but regular exposure to the actual allergen doesn't?
gpt
Think about working out. If you lift weights and put them under a little stress, they get stronger. If you lift so much weight that you tear the muscle, the muscle isn't going to get stronger.

The same idea applies here. Allergy shots are tiny amounts of the allergen. They're designed to get your body's immune system to recognize the allergen as something that isn't dangerous. Eating the actual allergen is a much higher quantity, and (much like tearing a muscle) elicits a dangerous reaction.