Side effects of antimicrobials can range from mild to severe. Common side effects include gastrointestinal disturbances (nausea, vomiting, diarrhea), allergic reactions, and skin rashes. More serious side effects can include nephrotoxicity (kidney damage), hepatotoxicity (liver damage), and ototoxicity (hearing loss). It is essential for healthcare providers to weigh the benefits and risks before prescribing antimicrobials.