The increasing presence of organic pollutants in the environment is one of the greatest environmental challenges of today. The use of organic substances in products such as pharmaceuticals, cosmetics, pesticides, and plastics is the cause of water pollution, which poses a serious threat to ecosystems. The increasing importance of this ecological problem has led to the development of wastewater treatment technologies, which include the process of biological treatment, i.e. the biodegradation of organic substances from wastewater by microbial catabolism. The main objective of this wastewater treatment process is to completely remove an organic pollutant or convert it into non-toxic substances with the help of the metabolism of microorganisms. Due to its cost-effectiveness and exceptional environmental safety, biodegradation of organic matter has become one of the most important wastewater treatment processes and is being used more and more frequently over time. Biodegradation is often used in the treatment of water contaminated with pharmaceutical products and their derivatives, which are formed by environmental factors and can be toxic to humans and other organisms with which they frequently come into direct contact. The most common organic xenobiotics of pharmaceutical origin found in the environment include painkillers such as diclofenac and paracetamol, and drugs used to treat type 2 diabetes such as metformin. This paper therefore describes their properties, the ecotoxicological risks of their presence in the environment and the possibilities of biodegradation.