We know how seriously the Torah takes the laws of Shabbat, yet for piku’aḥ nefesh – when there is danger to life – the laws of Shabbat are pushed aside.
The Gemara on today’s daf notes that this is true not only when there is a clear danger, but also when there is any makah shel ḥalal – an internal injury – we will automatically be willing to treat the person, although Talmidei Rabbeinu Yona explain that this does not refer to a minor pain or complaint, only a known injury or serious pain.
This discussion leads to a question about whether an injury or disease to teeth and gums would be included. Are they considered to be “internal”? As a proof to this question, the Gemara tells of Rabbi Yoḥanan who was suffering from tzafdina, and was treated by a Roman matron, who agreed to share the secret of the treatment if Rabbi Yoḥanan swore not to reveal it to others. Rabbi Yoḥanan replied “I swear to the God of Israel I will not reveal it.” Upon learning the cure, he told her that he would publicize it, explaining that he had taken a vow not to reveal it to the God of Israel, but to His people he planned to reveal it.
Clearly, Rabbi Yoḥanan viewed the information about the cure as being a life-and-death matter that had to be shared publicly. The Ritva and Meiri point out that even so, he was obligated to explain to the matron that his oath was not binding and that he planned to tell others the cure.
From the description in the Gemara, tzafdina appears to be scurvy, a disease marked by a lack of Vitamin C, which leads to a weakening of teeth and gums, internal bleeding and anemia. The descriptions in the Gemara of various methods that were used in an attempt to cure tzafdina were, apparently, attempts to make up the lack of this vitamin by ingesting it in a concentrated manner.