Hawzah News Agency – Q: My mother was ill for a period of almost 13 years and could not fast. I know for certain that what prevented her from this duty was her need to take medicine. Please tell us if it is obligatory for her to perform the qaḍā’ for these missed fasts.
A: If she was not able to fast due to her illness, she does not have to perform the qaḍā’ for those days.
Source: https://www.leader.ir/en/book/32/Practical-Laws-of-Islam