Is it obligatory to say "Yarhamuk Allah" to a colleague who sneezes frequently due to illness every time she sneezes?

One is not obliged to say "Yarhamukallah" (may Allah have mercy on you) to someone who sneezes if the sneezing continues after the third time, based on the hadith: "If he sneezes, say 'Yarhamukallah' to him. Then if he sneezes, say 'Yarhamukallah' to him. Then if he sneezes, say 'Yarhamukallah' to him. Then if he sneezes, say 'You are suffering from a cold (madhnook)'." And the "madhnook" is one who has a cold. The narrator said, "I do not know if it was after the third or the fourth [sneeze]." Malik took the precautionary approach, so he concluded that saying "Yarhamukallah" is done for up to three sneezes, and then it is no longer required after that.