"Why don't we do that? We should take a drug test, prior, because I don't know what's going on with her, but at the beginning of her last debate, she was all pumped up at the beginning, and at the end it was like, 'Oh, take me down,' " Trump said, imitating Clinton.
He also noted Hillary could "barely reach her car."
Concerns about Hillary Clinton's health have been one of Trump's campaign points. The Republican nominee repeatedly questioned whether Clinton is physically fit to serve as a president, giving food for various conspiracy theories.
These concerns are based on various displays of physical inability by the Democratic nominee, such as coughing fits that could last for several minutes, or Hillary fainting mere steps away from her van after the 9/11 ceremony.
Donald Trump said he also agrees to undergo the drug test before the upcoming debates.