There’s a couple ways to read that, one being ‘at dosages which have been shown not to cause clinically significant side effects’. The other interpretations are more concerning, of course.
I vaguely remember reading that lithium in low doses has huge benefits with minimal to no side effects, but it’s generally not taken due to stigmatization from the downsides of people being forced to take way too much for mental illnesses in the past.
I have a pair of cheap UV protection sunsleeves that I’ve cut to just cover my wrists-forearms that I wet with a spray bottle when it’s crazy hot. Works incredibly well.