Antimicrobial side effects present as adverse drug reactions involving one or more organ systems. Although most antibiotics are safe considering their volume of use, some antimicrobials have the potential for life-threatening side effects. In general, β-lactams have the least frequent and least severe side effects. Although any antibiotic is capable of causing side effects, specific agents from each antibiotic class are more likely to do so than others. Clinicians should be familiar with the side-effect potential of individual antibiotics as well as the likelihood of specific agents being involved in an adverse reaction and should be familiar with the spectrum of organ involvement associated with particular antimicrobials.

Clinicians have a vast armamentarium of antimicrobials effective against a wide variety of pathogens. Most antimicrobials have a good safety profile. Physicians should consider the frequency and severity of potential adverse effects of antimicrobials when selecting agents for therapy.