Make room for the other version
Ask what the other person understood before assuming that you are arguing about the same facts. For a message about how to support someone waiting for a transplant, use this factual base: acknowledge the diagnosis or treatment only as they described it and remember the practical burden around it.
Correct the record precisely
Correct only what you can support, acknowledge any real impact, and propose a practical way to prevent repetition. Offer one specific task, flexible company, or ordinary contact that they can accept or ignore. Make the immediate next step clear enough that the recipient can answer without reconstructing the entire history.
Agree on a testable next step
Do not prescribe cures, compare outcomes, ask for optimism, or share their health information. Leave medical decisions to clinicians and contact urgent or emergency services when there is immediate danger. Do not recruit an audience, publish private evidence, or turn a misunderstanding into a campaign about character.