In addition to Cochrane:
JSTOR academic journal access during Covid-19‣
Scott Alexander Siskind has recently started writing about psychiatric conditions and treatments
Rob Wiblin listed these (hence the Australian picks : ) I'd be very happy to add to it if there are additional suggestions.
Crazy Meds for mental health treatment: http://www.crazy-meds.org/
UpToDate for treating diseases: http://uptodate.com/ [also suggested by Jim Babcock]
Therapeutic Guidelines for treating diseases: https://www.tg.org.au/
Red Book for screening for disease: https://www.racgp.org.au/.../goodpractice/20171-2/red-book/