Families often meet this subject through a letter or a question at a donation session, which can be alarming when it arrives without explanation. The rules are precautionary, and they exist because of a gap in testing rather than a new risk.
Why are there rules at all?
No blood test can screen donated blood for prion disease. Because screening is not possible, blood services manage the question by asking some groups of people not to donate.
Who is asked not to donate in the UK?
The donor selection guidelines list several groups. Anyone diagnosed with any form of CJD or another human prion disease. Anyone with two or more blood relatives who developed a prion-associated disease, or who has been told through genetic counselling that they are at risk. Anyone who has been told they are at increased risk because of surgery, a transfusion or a transplant, or that someone who received their blood or tissue later developed a prion disorder.
Also included are people who received a graft of dura mater, which is the membrane covering the brain, a corneal or other eye tissue graft, or hormone extracts taken from human pituitary glands. Those treatments stopped in the UK in 1986 and 1993.
Separately, anyone who has had a blood transfusion anywhere in the world since 1 January 1980 is asked not to donate.
Why 1980?
That date sits before BSE became widespread in cattle. The guidelines link the cut-off to variant CJD, and record that a person in the UK who had received blood from a donor who later developed variant CJD died of the disease in 2003, with several other recipients found to have been infected.
These are small numbers of people over decades, and the rule is a precaution that covers everyone rather than a sign that transfusion commonly carries this risk.
Does being asked not to donate mean I am ill?
No. Being in one of these groups says nothing about your own health. The rules are written to protect the blood supply, so they include people whose risk is theoretical or unquantified.
If you have been told you are at increased risk and want to understand why, the team that told you is the right place to ask, and your GP can arrange that conversation. This page cannot assess anyone’s own situation.
Who decides these rules?
In the UK the Advisory Committee on the Safety of Blood, Tissues and Organs advises ministers and health departments across the four nations on the safety of blood, cells, tissues and organs. The donor guidelines say they reflect that committee’s guidance and that of its predecessor, alongside requirements in the blood safety regulations.
Rules differ by country and change over time, so the national blood service is the place to check what currently applies where you live.
Where next
Tissue and organ donation covers donating organs and tissue. Care settings covers hospitals, care homes and care at home. The safety hub lists the other questions. The research version, with the assay and policy evidence, is blood and plasma, and the regulations atlas tracks the official documents.