Oohh, I should be looking up frostbite/hypothermia for my worldbuilding too- I will get back to you on that soonish
yay ty!
Alright, so-
Frostbite usually affects extremities, AKA fingers and toes. Bodies tend to prioritize keeping the internal organs at a stable temperature, so hands and feet tend to get neglected temperature-wise. The cold stiffness also makes it a lot harder to flex your fingers and grab things, clench a fist, etc., so that could be used for tension or drama.
Frostbite damage CAN BE PERMANENT. Severe cases can cause gangrene - tissue death. At this point, the affected areas are beyond saving.
Spoiler warning: gross, graphic.
Spoiler - click to show.
The dead tissue kinda shrivels up like raisins. It might fall off on its own.
Lesser frostbites can still cause blisters and take a few days or weeks to fully heal.
A good home treatment for minor frostbite is soaking in warm (not hot) water. Also, some side effects could be increased risk of catching a cold and potential hypothermia.
Speaking of which, hypothermia is pretty much turbo frostbite. While frostbite tends to affect hands, feet, and maybe arms and legs, hypothermia affects the internal organs, which are SUPER sensitive to temperature changes. Frostbite is, for the most part, completely survivable. Hypothermia can kill a person in an hour.
Hypothermia is a lot scarier because once someone has it, they aren't really able to help themselves. It causes memory loss, general confusion, drowsiness, slurred speech, and hands become even less useful. Once someone with hypothermia loses conscious and/or stops shivering, it's pretty much over, since shivering is the natural response to keep the internals at a stable temperature.
Instead of wet warmth, the best home treatment is DRY warmth. Warm drinks help, too, but professional help is the best overall for both severe frostbite and hypothermia.