What are the most concerning adverse effects of penicillins?

Superinfections, including Clostridioides difficile (C. diff) colitis, and Stevens-Johnson Syndrome are among the most concerning adverse effects of penicillins because they can lead to severe and potentially life-threatening conditions. Penicillins, while generally well-tolerated, can disrupt the normal flora of the gastrointestinal tract, which may result in overgrowth of pathogenic organisms like C. diff. This can lead to significant gastrointestinal problems, including severe diarrhea and colitis.

Stevens-Johnson Syndrome is a rare but serious skin reaction that can occur with penicillin use, characterized by flu-like symptoms followed by a painful rash that can lead to grave complications. This adverse effect highlights the importance of monitoring patients for any signs of skin rash or other systemic reactions after starting treatment with penicillins.

In contrast, gastrointestinal disturbances, while common, are often mild and self-limiting. Bone marrow suppression is generally more associated with other classes of antibiotics, and nephrotoxicity is not a primary concern for penicillins compared to other drugs. Understanding these adverse effects helps practitioners weigh the benefits of antibiotic therapy against potential risks, ensuring safe and effective patient care.