What is the ruling of the Sharia on the fast of one who swallowed medicine remaining in her mouth after rinsing with it in Ramadan, and what is the expiation for that?

If a fasting person swallows medicine after dawn (Fajr), she must make up that day without expiation, according to the majority of scholars. However, if she swallowed it before dawn and its taste remained, and she then swallowed her saliva, her fast is not invalidated because swallowing insignificant food remnants that mix with saliva does not invalidate the fast.