Abstract
Oral antibiotics are among the most frequently used medications in the community. Its adverse effects are generally considered to be infrequent and mild, and include allergies, toxicities and drug interactions. Antibiotics are able to harm patients by various mechanisms, not always well known. Knowledge of the clinically relevant antibiotic-associated adverse effects can allow a judicious use based on the principle first do no harm, primun non nocere. In this review we explore the main adverse effects of oral antibiotics with specific focus on β-lactams, macrolides, and fluoroquinolones.