Multivitamin/mineral (MVM) dietary supplements are popular and widely used dietary supplements in the general population. They contain vitamins and minerals of different compositions, amounts of components, and characteristics. They are used to help with additional intake of essential micronutrients in the body and to support specific functions in the body in certain patients' conditions or special groups of patients. Although they are very popular, the use of MVM dietary supplements is not entirely without risk to patient's health. It is known that vitamins and minerals, as components of MVM dietary supplements, can interact with drugs and different patients' health conditions. Also, it is important to take into account the range of doses for optimal intake of vitamins and minerals and the safety of their use in special groups of patients including children, pregnant women, and breastfeeding women. All of the above can cause a decrease or increase in the drug effect or MVM dietary supplement components or may increase the risk of patient's adverse outcomes. This diploma thesis provides a systematic overview and detailed explanations of the most important interactions of vitamins and minerals, as components of MVM dietary supplements, with drugs and patients' health conditions, as well as the safety of their use in children, pregnant women, and breastfeeding women. The thesis also emphasizes the key role of the pharmacist in the counseling of patients on the use of MVM dietary supplements.