There’s a line in TSoT that I forgot to gush about because I was so emotionally damaged by the ending.
Major Sholto asks John if he’s still on the tricyclics, to which John says he still goes back for a top up every now and again.
Oh my fragile heart.
When he was with Sherlock he stopped going to therapy. It could be assumed that he stopped taking his antidepressants too during that time. When Sherlock died he went back to therapy and so may have started back up with the medication then as well.
And now, even though Sherlock’s back, even though he’s in a loving committed relationship, he still takes antidepressants.
Our boy has been through some tough shit in those two years…
Oh, right. This. So that’s canon then.