Introduction:
The World Health Organization (WHO) recommended dexamethasone as the only effective drug for treatment severe cases of COVID-19.

Aim:
To study the organoprotective effect of blueberry leaves decoction during the experimental use of dexamethasone.

Material and methods:
Experimental studies were performed on 30 white outbred laboratory rats of white males (initial weight 200 g), which were kept on the standard diet of the vivarium of National Pirogov Memorial Medical University, Vinnytsya, Ukraine, which were divided into three groups: (1) intact rats, (2) animals treated intramuscularly with 6 mg of dexamethasone for 10 days, (3) rats which were intramuscular injected with dexamethasone in the recommended dose and simultaneously intragastrically using 2 mL of the decoction, which was prepared as follows: steamed 1 g of dry blueberry leaves (Vaccinium myrtillus) with 5 mL of boiling water, infused for 1 h.

Results and discussion:
Intramuscular administration of dexamethasone at a dose of 6 mg for 10 days (according to WHO recommendations for patients with COVID-19) causes severe degenerative changes in the type of dystrophy and atrophy of rat's liver, heart, kidneys, periodontium and retinas. Prophylactic intragastric administration of a decoction of blueberry leaves prevents the development of dystrophic changes in cells and tissues in studing organs caused by the action of dexamethasone.

Conclusions:
Therapeutic use of dexamethasone leads to severe morphological changes in the most important organ systems and preventive introduction of a decoction of blueberry leaves protects the development of adverse effects.