You will find bottles and cans filled with healing potion during your adventures. Drinking it will recover your HP. Should all your body parts have full HP or if the amount of healing exceeds your needs, any remaining healing will be put towards regrowing any limbs you might be missing.
Troll blood is a natural source of healing whereas healing liquid is industrially produced by distilling it. Therefore is has a less bloody taste and higher concentration of tissue repairing stem cells.