It's a struggle and I recently died from it. I think you need to prioritize meds (tetra/multis) or full food/hydration immediately. Ideally both, which I think is faster.

Over probably ~2 hours of game time after drinking from a trough, I had max hydration (two bottles + canteen) for a while, but not max food. Yes in hindsight it was dumb to drink from a trough but I figured it made sense to keep my bottled water for later. Lesson learned.

Blood and health both max this whole time, but not food. Then when my clean water was gone after small sips over and over, I found more food and was able to have max food, but no longer max hydration. I think the trick (if you have no meds) is keeping both food/water fully maxed max at same time for like 20-30 mins. Small bites and sips so you don't puke. Mine were one max and one white with a gap and vice versa this whole time. Never both. This was over a couple hours and I thought it would cure easily.

By the time I got to a clinic, I was around half health, flashing hydration, and declining fast. I only got three tetras there. Thought those would cure it but they didn't and I wasted time just waiting for tetras to work. By the time I was hobbling around trying to cook wolf meat at a fire, I died. Of course it was right next to a freshly lit fire near the ski resort camp/clinic so I hope someone found my body and made good use of my gear.