I was surprised by this too. From a background in writing code to control precision pumps, I have a good idea of what 50 µL looks like and it seemed like an awfully small amount. But I don't know how concentrated the oil is.

FWIW, I had an Indian co-worker who took peppermint oil frequently and said that it was very good for his upset stomach.

That's enough to turn a whole barrel of water detectably minty.