A retrospective case series of patients who self-medicated with Famotidine during coronavirus disease 2019 (COVID-19). The study will collect de-identified patient reported outcome measures of patients with confirmed COVID-19 who self-medicated with Famotidine at any dose during the period of illness. Data will be collected by questionnaire and telephone interview.

Inclusion criteria:

Age>18; Ability to give written informed consent for study participation; Confirmed diagnosis of COVID-19; Use of Famotidine at any dose during period of COVID-19 illness

Famotidine is a histamine-2 receptor antagonist, widely available over-the-counter, and is safely used for suppression of gastric acid production over a wide range of doses from 20mg once daily to 160mg four times daily. In computer-based simulations, Famotidine has been identified as a potential inhibitor of the 3-chymotrypsin-like protease (3CLpro). In a propensity score matched retrospective cohort study a significantly reduced risk for death or intubation (adjusted hazard ratio 0.43, 95% confidence interval 0.21-0.88) was identified for patients with COVID-19 who were taking Famotidine before or at the point of hospital admission. Some individuals have self-medicated with Famotidine while being outpatients with COVID-19. This study is aimed at collecting patient reported outcome measures from such individuals.

Inclusion Criteria:

Age >18 years; Ability to give written informed consent; Confirmed COVID-19 diagnosis; Famotidine use during COVID-19 illness

Exclusion Criteria:

none

The study allows participants from all demographics.

Individual participant data (IPD) will not be shared with other researchers. De-identified data will be reported in a case series publication. All participants have consented to having de-identified data included in a case series report.