On a cold Acute infection of the upper respiratory tract – the most common diseases to which people turn to therapists, otolaryngology, and even pulmonology. Patients call it a cold or acute respiratory disease – acute respiratory disease. Colds may have different symptoms: nasal congestion and runny nose, scratchy or sore throat, hoarseness, cough, fever, weakness, loss of appetite. Based on the combination and degree of severity of the symptoms the doctor makes a diagnosis, ie determines which part of the respiratory system is affected by inflammation: the nasal mucosa (rhinitis); paranasal sinuses (sinusitis), mucous membrane of larynx (laryngitis); mucosa of the pharynx (throat); wall of the trachea (windpipe) and etc. Infectious agents (most often viruses, but there may be bacteria) enter the mucosa, which is lined by all departments of the respiratory system. Here they are meet with the cells responsible for immune defense, which begin to produce special substances – "inflammatory mediators". Under the influence of these substances activate the natural defense mechanisms of the respiratory system, to combat infection. The mechanisms of protection include: enhanced production of mucus, which binds and removes bacteria from the body, cough, which helps to remove phlegm and mucus from the respiratory tract; vasodilation of the mucous membrane, causing its blood supply and improve the delivery of additional protective factors to the site of inflammation (immunoglobulins and other substances of immune cells).

However, in some cases, these reaction is defensive, causing much suffering to the patient. Vasodilation causes swelling of the mucous membrane, which in combination with excessive elaboration of mucus in the nose and phlegm in the bronchi makes breathing more difficult. There are plenty of drugs that help alleviate this condition: vasoconstrictor drop ease breathing means thinning mucus contribute to its elimination and soothe coughs; antihistamines reduce swelling mucosa. But sometimes a characteristic of SARS catarrhal syndrome associated bacterial infection, suggesting that complications of SARS. In this case there is need for antibiotics. Consequently, the main task of the doctor is an effective therapy of acute upper respiratory tract infections, prevention of complications and treatment of exacerbations of chronic processes.