Yoma 49a
Yoma 49a:8
All foods and drinks that healthy people ordinarily consume may be eaten or drunk for medicinal purposes, as the Sages did not prohibit such items under their decree against taking medicine on Shabbat.
לִשְׁתּוֹת, פְּשִׁיטָא? דִּתְנַן: כׇּל הָאוֹכָלִין אוֹכֵל אָדָם לִרְפוּאָה, וְכׇל הַמַּשְׁקִין שׁוֹתֶה!
Since it has been raised, the Gemara addresses the issue of cress juice on Shabbat: Did Rabbi Ḥanina permit him to drink cress juice? It is obvious that it is permitted to drink this juice; why would it be prohibited? As we learned in a mishna: All types of food that healthy people eat may be eaten by people even for medicinal purposes, and one may likewise drink all drinks for medicinal purposes, as the Sages did not include these in their decree against taking medicine on Shabbat.