What potential issue arises from excessive use of antibiotics?

Excessive use of antibiotics can lead to antimicrobial resistance, which occurs when bacteria adapt in such a way that they become resistant to the effects of these medications. This resistance happens when antibiotics kill off susceptible bacteria, but resistant strains survive and multiply. Over time, as more people are treated with antibiotics, the proportion of resistant bacteria can increase dramatically within a population, rendering standard treatments ineffective and making infections harder to treat.

This growing resistance raises significant public health concerns because it can lead to longer hospital stays, higher medical costs, and increased mortality. For diseases that were once easily treatable with antibiotics, the emergence of resistant strains complicates treatment protocols and forces healthcare providers to rely on more potent and often more expensive medications, which may have more severe side effects.

The other options, while relevant to the discussion of antibiotic use, do not directly capture the primary consequence of excessive antibiotic use. Immunity could be incorrectly invoked in the context of vaccines rather than antibiotics, enhanced disease severity would refer to the impact of resistant infections rather than the antibiotics themselves, and allergies to antibiotics are typically associated with individual reactions rather than a broad public health crisis.