Probably not as much harm as the factory farms that give antibiotics to all of their animals.
Only one half of antibiotic use is in agriculture, and they are not the kind that are used in human medicine.
OP is probably using a low dose which is worse, since it won't kill everything and encourages resistance.
Also they are exposing human pathogens to it, which is possibly more dangerous.
This thread is for asking any questions that might seem obvious, tangential, silly or what-have-you. Don't be shy, everyone has holes in their knowledge, though the fewer and the smaller we can make them, the better.
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