Pharmacovigilance (pharmakon – drug substance and vigilance) is scientific research and activities related to the detection, evaluation, understanding and prevention of adverse reactions or any other problems associated with a medicine. The pharmacovigilance system is one of the components of the quality management system (QMS) in accordance with the international standard ISO 9001-2015. Pharmacovigilance is an effective method of post-registration detection of adverse drug reactions – a spontaneous reporting system included in the Yellow Card Scheme. The main source of spontaneous messages is doctors, researchers, pharmacists and nurses.A large number of side effects of drugs, including rare side effects that cannot be detected during clinical trials have been revealed thanks to the spontaneous messages from around the world. One example of a rare side effect: information was received in 1995 about the possibility of tendon ruptures when taking fluoroquinolones. The aim of pharmacovigilance is safer and more effective use of medicines. Medicines bring great benefits to people, but none of them are 100% safe for them. While some medicines can cause serious side effects, most have a predominantly beneficial effect on people, even sometimes only causing minor harm (such as headache, rash, or fatigue). When considering a treatment option, the doctor and patient must decide whether the benefits are sufficient to accept the possibility of discomfort or harm that is already known and listed in the patient’s insert card. Occasionally, unexpected minor or major harm can occur. This is why surveillance and reporting is so important: the more knowledge we have about what patients have experienced, the better informed we are to prevent future harm. Medicines play an important role in our lives – they help to cure the disease, alleviate the symptoms of the disease, prevent the development of the disease and improve the quality of life. There is not a single medicine, whose use is not associated with risk. All medicines have side effects and contraindications. Side effects may result from the correct use of medicines, as well as from overdose or simultaneous use of a combination of two or more medicines, which is not provided for in the certificate of registration. The information indicated in the instructions is the result of many years of clinical research. The process of developing a new drug and bringing it to the market is quite long.