I bought some Chinese medicine for my friend. She was so happy and said,"That is so sweet of you. But how do I use it?" I told her the medicine was for external use, and I tried to explaine to her how should she put it on the skin. But I was not sure which verb should I use at that moment, should I say "paint", "brush" or "put"? So I read the instructions, and I found I should use "apply". That is to say, she can APPLY the medicine to her skin.

Then I was wondering, if that medicine was for external use or external application only, so how could I say those medicine that can be swallowed into mouth. Are they the internal use medicine? But speaking of internal use, that made me think of the documents I was dealing with at my work, "Confidential information, Internal use only."

So I asked my friend, "what are the opposite words for external use?" She told me, " we usually will say ORAL USE medicine."

Okay, so I learned some new words, external application & oral use.