Almost never. Your ABO group is fixed for life, a handful of extraordinary medical situations can make it appear to change. ## The honest answer The ABO genes sit on chromosome 9 and do not change. Rare exceptions: massive bone-marrow transplant (your new marrow makes the donor’s group), some leukemias weakening antigens, and rare bacterial enzymes stripping antigens in severe sepsis, all medical curiosities, not everyday events. If a lab once reported a different group than today, the far likelier explanation is a lab error in one of the tests, get it re-tested properly. ## If this is your moment Blood cannot wait for curiosity to settle, patients wait in hours, not weeks. If you are healthy and between 18 and 65, register as a donor (two minutes, phone OTP) and let the system call you only when someone near you actually needs your group.
Blood groups
Can your blood group change?
Almost never. Your ABO group is fixed for life, a handful of extraordinary medical situations can make it appear to change.
People also ask
Can blood group change from positive to negative?
Only after a bone-marrow transplant from a different-group donor, otherwise no.
My blood group tested different in two labs. How?
Most likely a testing error, re-test with proper grouping; discrepancies are common with rushed finger-prick kits.
Does diet or illness change blood group?
No. Some illnesses temporarily weaken antigen reactions in lab tests, which is not a true change.
About this article
Written by Assam Blood Donor team. Medical review: pending, content follows published national (NBTC/NACO) guidance and is for general education, not personal medical advice. Last updated 11 Sept 2026.
Sources: NBTC donor selection criteria · standard donation-centre practice
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Reading is step one. Registering is step two.
Two minutes, phone OTP, your own 6-digit sign-in code. We contact you only when a patient near you needs your group.
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