This trophy is fairly easy to get. Just make it through the entire game without using a medkit. Save early and save often.
However, this trophy is glitched (at least on the digital version).
I played through the game three times (for all the other achievements) and did not use any medkits on any of my playthroughs. Before doing my playthrough for
I also deleted and reinstalled the game, but the achievement still did not pop for me.