Hawzah News Agency – Q: An ophthalmologist ordered me not to fast due to an eye disease. But, I did not pay attention to his order and began fasting. However, while fasting I felt a pain in the afternoons on some days. Now, I wonder whether I should refrain from fasting or bear the pain until sunset. Basically, is it obligatory for me to fast? And should I maintain the fast on the days when I am not certain whether I can continue fasting until sunset or not? What should my intention be?

A: If you are confident — due to what your physician said — that fasting is harmful for your health or you fear so, then it is not obligatory for you to fast. In fact, it is not permissible for you to fast in such a situation, and the intention to fast is not correct when there is fear of harm. When there is no fear of harm, the fasting intention is not problematic, but the validity of your fast depends on the actual absence of harm.

Source: https://www.leader.ir/en/book/32/Practical-Laws-of-Islam