Rational antibiotic therapy is one of the most important components in the treatment of children with various infectious and inflammatory diseases. However, wide and sometimes unjustified use of AB in pediatric practice often leads to the development of a variety of complications. Children receiveing AB, especially during the first 5 years of life, are at a very high risk of developing antibiotic-associated diarrhea (AAD) which manifests itself in three or more episodes of unformed stools for two or more consecutive days or for 8 weeks after withdrawal. The most relevant pathogen of AAD is C. difficile which, according to various data, causes from 10 to 25% of AAD cases and 90 to 100% of all cases of pseudomembranous colitis (PMC). Given the high probability of developing dangerous complications such as PMC, special attention should be paid to the prevention of the infection associated with C. difficile by reducing the frequency of uncontrolled and unjustified use of AB. A new generation of eco-antibiotics can be recommended which allow to maintain diversity of the intestinal microbiota and are less likely to cause complications.