Viruses are small, simple formed microorganisms that inhabit and multiply in the living cells of humans and animals. Flu or influenza viruses belong to the Orthomyxoviridae family and are divided into influenza type A, B and C. Influenza is an acute inflammation of the respiratory system that is transmitted and spreads through the veins, making prevention difficult and its short incubation period makes it difficult to detect the infection early. It manifests itself with common clinical symptoms such as general weakness, fever, muscle pain, coughs and then problems with the respiratory and digestive system. Tips for preventing the infection include increased hygiene (hand washing, safe sneezing and coughing, use of one-time handkerchiefs), avoiding larger gatherings in the flu season, ventilating the premises, eating a diet rich in vitamins, outdoor physical activities, taking enough fluids, relaxing, avoiding cold, avoiding going to healthcare facilities and avoiding potential infected people. Another way of prevention is by vaccination that uses parts of the virus from last season. A type A influenza drugs can be treated with anti-inflammatory drugs that may have effects on the central nervous system. Treatment is mostly performed symptomatically and with rest and intake of fluids and vitamins.