(Mishnah): One may not eat Eizov Yon (a kind of hyssop) on Shabbos because healthy people do not eat it.

However, one may eat Yo'ezer and drink Avuvaro'ah (these will be explained later).

One may eat any food for Refu'ah, or drink any drink, except for Mei Dekalim or a cup of Ikarim, because they are for jaundice;

However, one may drink Mei Dekarin to quench his thirst or anoint with oil of Ikarim, not for Refu'ah.

(Gemara): A man asked about R. Shimon bar Karsena "may one drink Karortin (it is made from herbs, and cools the body) on Shabbos?

Answer (R. Shimon bar Karsena): If it is for pleasure, it is permitted. If it is for Refu'ah, it is forbidden.

Question: [The malady that it heals -] is it not from the lip and inside?! (Such ailments are dangerous, and override Shabbos!)

Answer: [Internal ailments override Shabbos] only when there is danger. (This malady, even though it is internal, is not dangerous.)

Our Mishnah permits eating Yo'ezer. This is Politarchavin. It permits drinking Avuvaro'ah. This is like its name (it was known at the time).