Page 43 - British Museum: SYTYGIB Medieval Castle

But not all medieval medicine was bad.
Some medieval treatments may have been successful, from herbal remedies used by wise women to ways of mending broken bones.
With the castle’s knights and soldiers fighting battles, or even just training for war, there were plenty of opportunities to learn techniques like setting broken bones in plaster and sealing wounds using egg whites. Old wine would be used to stop wounds getting infected and certain plants could send people to sleep when operations were taking place.
Archaeologists have discovered evidence of broken bones healing perfectly and skeletons of people who survived nasty sword wounds, so at least some docs (and barbers) knew what they were doing.
Still, if you ever travel back in time to a medieval castle and some guy comes at you with a hungry leech, do yourself a favour and get back in your time machine pronto.
This knight has terrible wounds!
Quick! Fetch a chicken!
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Health and medicine