Question Summary
If one cannot fast and pays fidya instead and then later becomes able to fast, are they required to make up the previous days of fasting, or does the fidya suffice?
Question Answer
In the Name of Allah, the Most Merciful and Compassionate
If after paying fidya due to an inability to fast, one returns to a state of health in which they can fast — they are required to make up the past fasts. [Ibn ‘Abidin, Radd al-Muhtar]
Not Fasting vs. Paying Fidya
The Sacred Law gives dispensation to those unable to fast due to elderly age or medical conditions.
A medical condition is seen as an excuse if one is reasonably sure that fasting will cause them harm, increase their sickness, or delay their recovery time. Such an excuse is sufficient to choose not to fast; they are still required to make up the missed fasts and do not pay fidya. [Tahtawi/Shurunbulali, Hashiyat Maraqi al-Falah]
On the other hand, if one’s sickness is such that they are not able to fast and they have no expectation of recovering in the future, such a person pays the fidya in place of the fasting; they have not required to make up the missed fasts (due to the added factor that they do not expect recovery). [Ibid.]
If, however, they do recover, they must make up the previous fasts. [Ibid.]
How is a Valid Excuse Established?
A valid excuse is established by either experience, clear signs, or the advice of a Muslim medical professional who bases their judgments on their knowledge of medicine and their knowledge of the injunctions of fasting established in the Sacred Law. [Ibn ‘Abidin, Radd al-Muhtar]
Most medical professionals do not advise based on Islam’s injunctions; thus, they do not meet the above conditions.
One may still take the medical professional’s advice and use it to help them come to their own conclusion as to whether they perceive, with reasonable surety, potential harm from fasting.
Hope this helps
Allah knows best
[Shaykh] Yusuf Weltch
Checked and Approved by Shaykh Faraz Rabbani