Study aim: The effect of Famotidine on cognitive and behavioral dysfunctions induced by COVID-19 Design: Randomized double blind and placebo-controlled clinical trial Settings and conduct: This study will be performed on patients with COVID-19 attending Imam Khomeini Hospital in Tehran Participants/Inclusion and exclusion criteria: Inclusion criteria: History of hospitalization due to COVID-19 - At least 20 days from the onset of symptoms, and 7 days from the last day of symptoms passed - Diagnosis of cognitive impairment (score 23 or less in MMSE test, or score 22 or less in MoCA test) - Age between 18-65. Exclusion criteria: Being psychotic - Presence of other psychiatric disorders - Using other psychiatric drugs or any drug which can affect cognitive performance - History of ECT during past 2 months - Presence of thyroid disease - Presence of kidney disease - Presence of liver disease - History of cognitive impairment or dementia - Pregnant or lactating women Intervention groups: Intervention group: Famotidine 80 mg per day for 3 months. Control group: Placebo for 3 months. Main outcome variables: Severity of cognitive impairments