What causes graft-versus-host disease?

An allogeneic transplant uses blood-forming stem cells from another person. The donated graft contains immune cells called T cells. If these cells recognise proteins on the recipient’s tissues as different, they can release signals that cause inflammation and tissue injury.

The skin, mouth, eyes, liver and digestive tract can be affected. GVHD may appear earlier or later after transplant and can be short-lived or persistent. The degree of tissue matching, donor and recipient factors, and the transplant approach influence risk, but no single feature predicts an individual outcome.

Attend the transplant team’s planned reviews and take immune-suppressing medicines exactly as directed. Report new rash, diarrhoea, nausea, mouth soreness, dry eyes, yellowing of the skin, dark urine or tightening skin. Do not start supplements, stop medicines or use new creams without checking first.

Your team may examine affected areas, review blood tests and adjust immune treatment. Early reporting helps distinguish GVHD from infection, medicine effects or another transplant complication. Read more about [Allogeneic Stem Cell Transplant](/treatments/cellular-and-transplant-therapy/allogeneic-stem-cell-transplant/).

Contact the transplant team promptly for a new rash, repeated loose stools, inability to drink, worsening mouth pain, eye pain or vision change. Seek urgent help for breathing difficulty, confusion, severe dehydration, rapidly spreading rash, high fever or signs of infection.

Which symptoms should I report the same day? Which organs are you monitoring in my follow-up? How will you distinguish GVHD from infection? What should I do if I miss an immune-suppressing dose? When should a skin or gut sample be considered?