Question: What is the amount of bleeding caused by Hijaamah (cupping) which invalidates a person’s Sawm (Fast)? Does a person’s Sawm become invalid if they bleed extensively during performance of an oral surgical operation?
Answer: Hijaamah invalidates Sawm according to the correct opinion maintained by scholars. This is based on the Hadith which reads: A man who cups or gets himself cupped will have their Sawm broken. The same applies to withdrawing a large amount of blood from the fasting person. However, Sawm will continue to be valid if blood is emitted because of a surgical operation. This is because emission of blood in this case is not out of the patient’s own will... read more here.