* patients with a partial oxygen pressure \< 90% and who have required hospitalization * patients who have required intensive care * any condition which, in the opinion of the principal investigator, would prevent full participation in and compliance with the trial protocol * patients who have been involved in any other interventional studies * patients with uncontrolled type i or type ii diabetes mellitus (dm) * patients with severe liver failure (child pugh score ≥ c, ast\> 5 times the upper limit of normal (uln) * patients with severe renal failure (gfr ≤30 ml/min/1.73 m2) or continuous dialysis (hemodialysis, peritoneal dialysis) or continuous renal replacement therapy * patients with serious cardiac problems such as heart failure * patients with hypersensitivity to montelukast or other drugs in the study * patients with rare hereditary problems of galactose / fructose intolerance, glucose- galactose malabsorption or sucrase-isomaltase insufficiency * pregnant and lactating women * patients who cannot use sexual abstinence or appropriate contraceptive method during the study * patients who are treated with any other antiviral drugs for covid-19 in the last 30 days

* patients with a partial oxygen pressure \< 90% and who have required hospitalization * patients who have required intensive care * any condition which, in the opinion of the principal investigator, would prevent full participation in and compliance with the trial protocol * patients who have been involved in any other interventional studies * patients with uncontrolled type i or type ii diabetes mellitus (dm) * patients with severe liver failure (child pugh score ≥ c, ast\> 5 times the upper limit of normal (uln) * patients with severe renal failure (gfr ≤30 ml/min/1.73 m2) or continuous dialysis (hemodialysis, peritoneal dialysis) or continuous renal replacement therapy * patients with serious cardiac problems such as heart failure * patients with hypersensitivity to montelukast or other drugs in the study * patients with rare hereditary problems of galactose / fructose intolerance, glucose- galactose malabsorption or sucrase-isomaltase insufficiency * pregnant and lactating women * patients who cannot use sexual abstinence or appropriate contraceptive method during the study * patients who are treated with any other antiviral drugs for covid-19 in the last 30 days

- patients with a partial oxygen pressure < 90% and who have required hospitalization - patients who have required intensive care - any condition which, in the opinion of the principal investigator, would prevent full participation in and compliance with the trial protocol - patients who have been involved in any other interventional studies - patients with uncontrolled type i or type ii diabetes mellitus (dm) - patients with severe liver failure (child pugh score ≥ c, ast> 5 times the upper limit of normal (uln) - patients with severe renal failure (gfr ≤30 ml/min/1.73 m2) or continuous dialysis (hemodialysis, peritoneal dialysis) or continuous renal replacement therapy - patients with serious cardiac problems such as heart failure - patients with hypersensitivity to montelukast or other drugs in the study - patients with rare hereditary problems of galactose / fructose intolerance, glucose- galactose malabsorption or sucrase-isomaltase insufficiency - pregnant and lactating women - patients who cannot use sexual abstinence or appropriate contraceptive method during the study - patients who are treated with any other antiviral drugs for covid-19 in the last 30 days

- patients with a partial oxygen pressure < 90% and who have required hospitalization - patients who have required intensive care - any condition which, in the opinion of the principal investigator, would prevent full participation in and compliance with the trial protocol - patients who have been involved in any other interventional studies - patients with uncontrolled type i or type ii diabetes mellitus (dm) - patients with severe liver failure (child pugh score ≥ c, ast> 5 times the upper limit of normal (uln) - patients with severe renal failure (gfr ≤30 ml/min/1.73 m2) or continuous dialysis (hemodialysis, peritoneal dialysis) or continuous renal replacement therapy - patients with serious cardiac problems such as heart failure - patients with hypersensitivity to montelukast or other drugs in the study - patients with rare hereditary problems of galactose / fructose intolerance, glucose- galactose malabsorption or sucrase-isomaltase insufficiency - pregnant and lactating women - patients who cannot use sexual abstinence or appropriate contraceptive method during the study - patients who are treated with any other antiviral drugs for covid-19 in the last 30 days