Antibiotics are among the most frequently used drugs in outpatients. Their side effects can lead to emergency room visits, hospital admissions and considerable economic costs. In this article, we will discuss some often-overlooked side effects of selected antibiotics used in outpatients. Adverse events such as hematological toxicity of linezolid, neurotoxicity of metronidazole, nitrofurantoin pulmonary toxicity or even risk of aortic aneurysm from fluoroquinolones require cautious use and an individualized assessment of the risk-benefit.