Generally speaking, if someone prepares a mixture that is to be ingested for medicinal purposes, it will not receive the normal blessing beforehand. The Gemara points out, however, that if it was prepared as ordinary food or drink, even though it also has medicinal qualities, it would be appropriate to recite a blessing before eating. Thus, Rav Ḥisda explains that when Rav requires a shehakol blessing (“By Whose word all things came to be”) on shetita and Shmuel requires a borei minei mezonot (“Who creates the various kinds of nourishment”), it is not because they disagree. Rather they are talking about different cases. Shmuel is discussing a case where a thick mixture was made to be eaten; Rav is discussing a case where a thin mixture was made to be used as medicine.
With regard to the assumption that this mixture is essentially medicinal, Rav Yosef raised a challengefrom the laws of Shabbat:
And they agree that one may mix shetita on Shabbat and drink Egyptian beer, which contains a mixture of a pungent spice in flour. And if it enters your mind to say that when one prepares shetita, his intention is for medicinal purposes, is medicine permitted on Shabbat?
Abayye said to Rav Yosef: Do you not hold that to be true? Didn’t we learn in a Mishna: All foods that are commonly eaten; a person may eat them for medicinal purposes on Shabbat, and all drinks that are not designated for medicinal purposes, a person may drink them for medicinal purposes on Shabbat. But what can you say in explaining that ruling? The man’s intention is for the purpose of eating; here too, when he mixes the shetita, the man’s intention is for the purpose of eating.
Thus, something that is prepared for ordinary ingestion may be eaten on Shabbat, even if it has medicinal qualities.
The Sages decreed that one may only use medicine on Shabbat in life-threatening circumstances or instances of grave danger. Consequently, they prohibited all curative actions, especially preparing and taking medicine. In tractate Shabbat, there is a discussion with regard to various foods and whether they should be considered as food that may be eaten on Shabbat, even by those deriving medicinal benefit; or whether they are prohibited, because their primary use is medicinal, which is prohibited by rabbinic decree.