Question: My brother suffers from a gastric ulcer. His doctor restricted the foods he is allowed to eat and prohibited him from observing Sawm (Fast) for the next five years. My brother attempted to fast, but it badly affected his health. What is the ruling on this case?
Answer: If this is the condition of your brother, and the doctor who advised him to abstain from Sawm is reliable, honest and knowledgeable, then he should follow his doctor’s advice. Therefore, he should not fast during the month of Ramadaan until his health improves to the extent that he is able to observe Sawm... read more here.