According to some authors, the prevalence of onychomycosis in the general population is 10- 20%, it increases with age and is 31% in people aged over 60 years. This affects the quality of life of patients, the risk of infecting contact persons and social adaptation. The treatment of such patients is long-term and not always effective due to concomitant pathology, which should be taken into consideration and corrected by the complex therapy for patients with onychomycosis.

In the view of recent events in the world, namely the pandemic, the problem of hair loss in people who have suffered a Coronavirus infection is becoming increasingly frequent in the practice of dermatologists. The connection between the hair loss and COVID-19 still needs to be investigated.

In the problem of eczema, the vascular component of its pathogenesis is of the topical importance. It has been established that the immune conflict condition is accompanied by the intensification of production or release of a wide range of substances exhibiting vasoactive effect as well. In such cases, one can consider changes in the vascular wall with subsequent activation of the thrombocytic-vascular and coagulation links of the haemostasis. Disagreement of literature data, as well as the need for therapeutic correction of haemocoagulation disorders in eczema patients necessitated further in-depth study of this process.

Stevens–Johnson syndrome (SJS), which is a drug-induced disease in 50% of cases, is increasingly common in everyday practice. A determining role in the pathogenesis of pathological conditions (inflammation, shocks of various genesis, etc.) plays a unique extra- and intracellular messenger, i. e., the nitrogen oxide (NO) system acts as an endogenous regulator in various dermatoses. In physiological concentrations, NO interacting with reactive oxygen species exhibits antioxidant properties, in case of metabolic disorders associated with the NO accumulation in tissues, and said reactions promote highly toxic substances adversely affecting the disease course. The NO biological action wide scope determines the interest in studying the NO-NOS system (nitrate ions (NO3-), nitrite ions (NO2-)) in patients with SJS, which is accompanied by the involvement of all body systems and defines the disease prognosis.

Acne remain an immediate problem in dermatology due to the tendency for increase of severe forms with frequent recurrence and damage of significant skin areas, which are the causes of temporary impaired productivity and reduced social activity in patients. This determines its important medical and social role. The aim of our research was to study the indicators of skin and intestine microbiocenosis and immunological parameters in patients with acne.