John Balmes, a pulmonologist at Zuckerberg San Francisco General Hospital, warned that even breathing fumes from bleach could cause severe health problems.
He told Bloomberg News: "Inhaling chlorine bleach would be absolutely the worst thing for the lungs. The airway and lungs are not made to be exposed to even an aerosol of disinfectant.
"Not even a low dilution of bleach or isopropyl alcohol is safe. It's a totally ridiculous concept."
Mr Trump has previously hyped a malaria medication, hydroxycloroquine, as a possible treatment for coronavirus, though he has stopped touting that drug recently.
This week a study of coronavirus patients in a US government-run hospital for military veterans found more deaths among those treated with hydroxychloroquine than those treated with standard care.