Ruling on Blood Tests While Fasting and Their Impact on the Fast

❀ Shar‘i Ruling on Blood Tests While Fasting

Source: Fatāwā Arkan-e-Islam

✦ The Question

Does undergoing a blood test during fasting break the fast?

✦ Shar‘i Answer

Al-ḥamdu lillāh, waṣ-ṣalātu was-salāmu ʿalā Rasūlillāh, Ammā Baʿd!

✔ Taking a small amount of blood for medical testing during fasting does not invalidate the fast.
The explanation is provided below:

➊ Taking a Small Amount of Blood for Testing

❀ Blood is often withdrawn in small quantities for diagnostic purposes.
❀ This small amount does not weaken the body significantly, nor does it resemble cupping (ḥijāmah) in its effect.
❀ Hence, it does not break the fast.

➋ Foundational Principle

✔ The default Shar‘i principle is that a fast remains valid unless a clear proof exists that it has been nullified.
✔ In the case of a simple blood test, no such evidence exists to declare the fast broken.

➌ What About Donating a Large Amount of Blood?

✘ If a large amount of blood is taken from the fasting person—such as for blood donation—then:
❀ It carries the same effect as cupping,
❀ And therefore, breaks the fast according to many scholars.

Exception:
✔ Donating blood during fasting is only permitted if:
◈ The recipient is in a critical condition,
◈ Waiting until sunset is not possible,
◈ Medical professionals confirm that immediate donation is necessary to save a life or treat a severe condition.

➍ What to Do If the Fast Is Broken Due to Blood Donation?

❀ If a fasting person is compelled to donate a large amount of blood, and their fast is nullified:

✔ They may eat and drink afterward to regain strength.
✔ They must later make up (qadhā’) for that day’s fast.

✔ Summary:

ھٰذَا مَا عِندِي وَاللّٰهُ أَعْلَمُ بِالصَّوَابِ