* randomization \> 72 hours of meeting inclusion criteria * randomization \> 7 days of symptom onset * currently taking an angiotensin converting enzyme inhibitor (acei) or angiotensin receptor blocker (arb) * prior reaction or intolerance to an arb or ace inhibitor, including but not limited to angioedema * pregnant or breastfeeding women * females able to have children not currently taking a protocol allowed version of contraception: intrauterine device, depo-formulation of hormonal contraception (e.g. medroxyprogesterone acetate/depo-provera), subcutaneous contraceptive (e.g. nexplanon), daily oral contraceptives with verbalized commitment to taking daily throughout the study, condom use or abstinence during the study. all participants of child bearing potential enrolled in this fashion will be informed of the teratogenic risks. * patient reported history or electronic medical record history of kidney disease, defined as: 1. any history of dialysis 2. history of chronic kidney disease stage iv 3. estimated glomerular filtration rate (egfr) of \< 30ml/min/1.73 m2 (must be have been measured within 1 month of enrollment) 4. other kidney disease that in the opinion of the investigator, would affect losartan clearance * patient reported dehydration and significantly decreased urine output in the past 72 hours * most recent systolic blood pressure prior to enrollment \<110 mmhg * patient reported history or electronic medical record history of severe liver disease, defined as: 1. cirrhosis 2. history of hepatitis b or c 3. other liver disease that in the opinion of the investigator, would affect losartan clearance 4. documented ast or alt \> 3 times the upper limit of normal within 3 months of randomization (if available in electronic medical record) * potassium \>5.0 mmol/l (must have been measured within 1 month) of enrollment * concurrent treatment with aliskiren * inability to obtain informed consent * enrollment in another blinded randomized clinical trial for covid

* randomization \> 72 hours of meeting inclusion criteria * randomization \> 7 days of symptom onset * currently taking an angiotensin converting enzyme inhibitor (acei) or angiotensin receptor blocker (arb) * prior reaction or intolerance to an arb or ace inhibitor, including but not limited to angioedema * pregnant or breastfeeding women * females able to have children not currently taking a protocol allowed version of contraception: intrauterine device, depo-formulation of hormonal contraception (e.g. medroxyprogesterone acetate/depo-provera), subcutaneous contraceptive (e.g. nexplanon), daily oral contraceptives with verbalized commitment to taking daily throughout the study, condom use or abstinence during the study. all participants of child bearing potential enrolled in this fashion will be informed of the teratogenic risks. * patient reported history or electronic medical record history of kidney disease, defined as: 1. any history of dialysis 2. history of chronic kidney disease stage iv 3. estimated glomerular filtration rate (egfr) of \< 30ml/min/1.73 m2 (must be have been measured within 1 month of enrollment) 4. other kidney disease that in the opinion of the investigator, would affect losartan clearance * patient reported dehydration and significantly decreased urine output in the past 72 hours * most recent systolic blood pressure prior to enrollment \<110 mmhg * patient reported history or electronic medical record history of severe liver disease, defined as: 1. cirrhosis 2. history of hepatitis b or c 3. other liver disease that in the opinion of the investigator, would affect losartan clearance 4. documented ast or alt \> 3 times the upper limit of normal within 3 months of randomization (if available in electronic medical record) * potassium \>5.0 mmol/l (must have been measured within 1 month) of enrollment * concurrent treatment with aliskiren * inability to obtain informed consent * enrollment in another blinded randomized clinical trial for covid

randomization > 72 hours of meeting inclusion criteria randomization > 7 days of symptom onset currently taking an angiotensin converting enzyme inhibitor (acei) or angiotensin receptor blocker (arb) prior reaction or intolerance to an arb or ace inhibitor, including but not limited to angioedema pregnant or breastfeeding women females able to have children not currently taking a protocol allowed version of contraception: intrauterine device, depo-formulation of hormonal contraception (e.g. medroxyprogesterone acetate/depo-provera), subcutaneous contraceptive (e.g. nexplanon), daily oral contraceptives with verbalized commitment to taking daily throughout the study, condom use or abstinence during the study. all participants of child bearing potential enrolled in this fashion will be informed of the teratogenic risks. patient reported history or electronic medical record history of kidney disease, defined as: any history of dialysis history of chronic kidney disease stage iv estimated glomerular filtration rate (egfr) of < 30ml/min/1.73 m2 (must be have been measured within 1 month of enrollment) other kidney disease that in the opinion of the investigator, would affect losartan clearance patient reported dehydration and significantly decreased urine output in the past 72 hours most recent systolic blood pressure prior to enrollment <110 mmhg patient reported history or electronic medical record history of severe liver disease, defined as: cirrhosis history of hepatitis b or c other liver disease that in the opinion of the investigator, would affect losartan clearance documented ast or alt > 3 times the upper limit of normal within 3 months of randomization (if available in electronic medical record) potassium >5.0 mmol/l (must have been measured within 1 month) of enrollment concurrent treatment with aliskiren inability to obtain informed consent enrollment in another blinded randomized clinical trial for covid

randomization > 72 hours of meeting inclusion criteria randomization > 7 days of symptom onset currently taking an angiotensin converting enzyme inhibitor (acei) or angiotensin receptor blocker (arb) prior reaction or intolerance to an arb or ace inhibitor, including but not limited to angioedema pregnant or breastfeeding women females able to have children not currently taking a protocol allowed version of contraception: intrauterine device, depo-formulation of hormonal contraception (e.g. medroxyprogesterone acetate/depo-provera), subcutaneous contraceptive (e.g. nexplanon), daily oral contraceptives with verbalized commitment to taking daily throughout the study, condom use or abstinence during the study. all participants of child bearing potential enrolled in this fashion will be informed of the teratogenic risks. patient reported history or electronic medical record history of kidney disease, defined as: any history of dialysis history of chronic kidney disease stage iv estimated glomerular filtration rate (egfr) of < 30ml/min/1.73 m2 (must be have been measured within 1 month of enrollment) other kidney disease that in the opinion of the investigator, would affect losartan clearance patient reported dehydration and significantly decreased urine output in the past 72 hours most recent systolic blood pressure prior to enrollment <110 mmhg patient reported history or electronic medical record history of severe liver disease, defined as: cirrhosis history of hepatitis b or c other liver disease that in the opinion of the investigator, would affect losartan clearance documented ast or alt > 3 times the upper limit of normal within 3 months of randomization (if available in electronic medical record) potassium >5.0 mmol/l (must have been measured within 1 month) of enrollment concurrent treatment with aliskiren inability to obtain informed consent enrollment in another blinded randomized clinical trial for covid

- randomization > 72 hours of meeting inclusion criteria - randomization > 7 days of symptom onset - currently taking an angiotensin converting enzyme inhibitor (acei) or angiotensin receptor blocker (arb) - prior reaction or intolerance to an arb or ace inhibitor, including but not limited to angioedema - pregnant or breastfeeding women - females able to have children not currently taking a protocol allowed version of contraception: intrauterine device, depo-formulation of hormonal contraception (e.g. medroxyprogesterone acetate/depo-provera), subcutaneous contraceptive (e.g. nexplanon), daily oral contraceptives with verbalized commitment to taking daily throughout the study, condom use or abstinence during the study. all participants of child bearing potential enrolled in this fashion will be informed of the teratogenic risks. - patient reported history or electronic medical record history of kidney disease, defined as: 1. any history of dialysis 2. history of chronic kidney disease stage iv 3. estimated glomerular filtration rate (egfr) of < 30ml/min/1.73 m2 (must be have been measured within 1 month of enrollment) 4. other kidney disease that in the opinion of the investigator, would affect losartan clearance - patient reported dehydration and significantly decreased urine output in the past 72 hours - most recent systolic blood pressure prior to enrollment <110 mmhg - patient reported history or electronic medical record history of severe liver disease, defined as: 1. cirrhosis 2. history of hepatitis b or c 3. other liver disease that in the opinion of the investigator, would affect losartan clearance 4. documented ast or alt > 3 times the upper limit of normal within 3 months of randomization (if available in electronic medical record) - potassium >5.0 mmol/l (must have been measured within 1 month) of enrollment - concurrent treatment with aliskiren - inability to obtain informed consent - enrollment in another blinded randomized clinical trial for covid

- randomization > 72 hours of meeting inclusion criteria - randomization > 7 days of symptom onset - currently taking an angiotensin converting enzyme inhibitor (acei) or angiotensin receptor blocker (arb) - prior reaction or intolerance to an arb or ace inhibitor, including but not limited to angioedema - pregnant or breastfeeding women - females able to have children not currently taking a protocol allowed version of contraception: intrauterine device, depo-formulation of hormonal contraception (e.g. medroxyprogesterone acetate/depo-provera), subcutaneous contraceptive (e.g. nexplanon), daily oral contraceptives with verbalized commitment to taking daily throughout the study, condom use or abstinence during the study. all participants of child bearing potential enrolled in this fashion will be informed of the teratogenic risks. - patient reported history or electronic medical record history of kidney disease, defined as: 1. any history of dialysis 2. history of chronic kidney disease stage iv 3. estimated glomerular filtration rate (egfr) of < 30ml/min/1.73 m2 (must be have been measured within 1 month of enrollment) 4. other kidney disease that in the opinion of the investigator, would affect losartan clearance - patient reported dehydration and significantly decreased urine output in the past 72 hours - most recent systolic blood pressure prior to enrollment <110 mmhg - patient reported history or electronic medical record history of severe liver disease, defined as: 1. cirrhosis 2. history of hepatitis b or c 3. other liver disease that in the opinion of the investigator, would affect losartan clearance 4. documented ast or alt > 3 times the upper limit of normal within 3 months of randomization (if available in electronic medical record) - potassium >5.0 mmol/l (must have been measured within 1 month) of enrollment - concurrent treatment with aliskiren - inability to obtain informed consent - enrollment in another blinded randomized clinical trial for covid