Peppermint

Let's pay another visit to Healer Keisha from Mercedes Lackey's novel Owlsight, whom we already met once before when discussing the healing qualities of wormwood. Keisha, as the village healer with a neat kitchen garden, has many healing herbs at hand. In the following snippet, she's treating a little boy who'd been in a fight with the village bully and is now sporting a bleeding nose and a black eye:

Her bit of advice had certainly silenced the child anyway; he seemed to be pondering it as they waited for his nose to stop bleeding. When Keisha judged that it had been long enough, she had him sit up and cautiously took the rag away from his nose. There was no further leakage, so she got up and mixed him a quick potion; chamomile for the ache in his eye and nose, mash-mallow and mint to counter any tummy upset from swallowing blood, and honey and allspice to make it into a treat.

So will this potion work as Keisha intends?

As for soothing an upset stomach - be it from swallowing too much blood or from the tension caused by the fight the boy has been through - the potion will certainly do that. Not only marshmallow and mint, but also chamomile, are all effective remedy for treating stomach upsets and other intestinal problems. Whether chamomile will also help with the boy's aching nose is doubtful, though it does have a calming effect on the psyche, so it might soothe away his upset - and with it, the pain.