system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Allergy medicine. Since it is an anti-histemine, does it not suppress the immune system? Is it easier to catch things like influenza or the cold while on allergy medicine?
gpt
Your immune system is kind of like a highway. There are all sorts of things on the highway to prevent cars from driving recklessly. There are two ways to enforce traffic laws on the highway, physical ~~barriers~~ deterrents and cops. The physical ~~barriers~~ deterrents are your innate immune response, the cops are the adaptive immune response. Histamine is a physical ~~barriers~~ deterrents, in our analogy, let's call it a speed bump. Speed bumps affect all traffic on the highway. If you have speed bumps engaged when you don't need them, like if you are exposed to an allergen such as pollen, it's a hassle for everyone involved. Allergy medicine turns off the speed bumps, but the cops are still around, and there are other physical ~~barriers~~ deterrents still present. 

EDIT: Changed barriers to deterrents to prevent confusion with the physical barriers used by the human body.