Why do you need to go to a hospital for 1st degree frostbite if you don't for a first degree heat burn and frostbite is essentially a cold burn?

You don't: Necessarily need to go to the hospital for first degree frost bite, "frost nip" It is the mildest form, most superficial, involving just the epidermis. I think a hospital visit is warranted if large body surface areas are involved, or if you aren't sure how severe it is. Telling the degree of cold injury can be hard to tell. BTW ,extensive first degree heat burns should be seen by a doctor also.