During a coronavirus taskforce briefing on Thursday, he suggested research into whether Covid-19 might be treated by injecting disinfectant into the body.
He also appeared to propose irradiating patients’ bodies with UV light.
On Friday, Trump said his comments had been made “sarcastically”.
Doctors have warned that some people might take the president’s comments seriously.
Speaking to the BBC, Dr Jonathan Spicer warned that “these products have corrosive properties that melt or destroy the lining of our innards”.