Healing bandage

Healing bandages were found in the TARDIS first aid kit. A healing bandage had coloured parts that were medicine. When applied to a wound, the medicine would go into the wound and the colour would disappear. When the bandage was completely white, the wound was healed.

When the First Doctor hit his head, Barbara used a healing bandage given to her by Susan to bandage the Doctor's wound. (TV: The Edge of Destruction)