Right now just by waiting over time your health will go to 80-85% relatively quick (within like 10-15 minutes) Add an item such as "Bandage" or "Painkiller" that will fill the rest of your health to 100%.
Having to go to Central MD and wait for a medic over small stuff isn't realistic as you wouldn't drive to the hospital to get a painkiller or a bandaid, you would buy it at the store and apply it yourself. Just make it have like a 1 minute timer so that way it's not used in combat. This al
If in the current state it should be added you shouldn't be able to bandage until at HP cap. When at HP cap you could bandage and it would take a couple minutes so it wouldn't just get abused mid fight.
If you wanted to add a new system. Maybe if you hit red HP you had to go see a "doctor" but if you was still in the green, maybe a "first-aid kit" could heal you back up in turn for it taking maybe 5 minutes or something and consuming the item.