Influenza A and B epidemics, occasionally pandemics, are characterized by high morbidity and mortality rates. In most cases, an uncomplicated disease ends with recovery, but unfavorable outcomes, up to lethal, are possible, especially in premature, low birth weight, infants and young children, old people, pregnant and postpartum women, with chronic diseases, immunocompromised, receiving salicylates and anticoagulants. The use of modern diagnostic methods allows early detection of patients with influenza, distinguishing them from the total number of patients with respiratory infections. This allows you to optimize the timing of the examination, avoid unnecessary prescription of antibiotics, and timely prescribe specific chemotherapy and chemoprophylaxis. During epidemics, in the presence of an epidemiological history, the conclusion of the clinician is decisive for the diagnosis. Vaccination is an excellent method of preventing or relieving the flu. However, in case of an unfavorable course of the disease, in risk groups, in closed groups, it is recommended to use chemotherapy, pre-exposure or post-exposure chemoprophylaxis. Numerous studies have proven the effectiveness of the use of the drug oseltamivir, a specific blocker of the virus neuraminidase. As a result, its replication stops. The drug does not complicate the vaccination, it can be used in vaccinated people, in all age groups, is available in different dosages, and can be used with food. Treatment for uncomplicated influenza lasts 5 days. In certain situations, chemoprophylaxis and chemotherapy with the specific antiviral drug oseltamivir can help control influenza outbreaks in certain populations.