Graft-versus-host disease (GVHD) is a condition where transplanted immune cells from a donor attack the recipient’s body. The name describes exactly what happens: the “graft” (donated tissue) launches an immune assault against the “host” (the person who received the transplant). It’s the reverse of typical organ rejection, where the host’s immune system attacks the graft. GVHD most commonly occurs after a bone marrow or stem cell transplant and can range from mild skin rashes to life-threatening organ damage.
GVHD vs. Transplant Rejection
These two conditions are mirror images of each other, and the terminology trips people up. In standard transplant rejection (sometimes called host-versus-graft disease), your own immune system recognizes a transplanted organ, like a kidney or liver, as foreign and tries to destroy it. This is the scenario most people think of when they hear “organ rejection.”
GVHD works in the opposite direction. Instead of your body rejecting the transplant, the transplant rejects you. This happens because bone marrow and stem cell transplants contain functioning immune cells from the donor. Once those donor cells settle into your body, they can identify your tissues as foreign threats and begin attacking your skin, gut, liver, and other organs. The donated cells essentially treat your entire body the way your immune system would treat a splinter.
How GVHD Develops
The process unfolds in phases. During a stem cell transplant, the donated tissue comes from a genetically different person. That donor tissue contains a type of immune cell called a T-cell, which is trained to recognize “self” versus “non-self” based on specific proteins on the surface of cells. When donor T-cells encounter the recipient’s cells, they detect unfamiliar surface proteins and flag the recipient’s tissues as invaders.
From there, the donor’s immune cells multiply rapidly and begin damaging the recipient’s organs. This is the same type of immune reaction your body uses to fight infections or reject foreign material, just aimed at the wrong target. The skin, gastrointestinal tract, and liver are the most commonly affected organs, though chronic cases can involve nearly any part of the body.
Acute vs. Chronic GVHD
GVHD comes in two forms, traditionally distinguished by timing. Acute GVHD typically appears within the first 100 days after transplant, while chronic GVHD develops later. In practice, the distinction now relies more on the specific symptoms than on a strict calendar cutoff, since features of both forms can overlap in timing.
Acute GVHD tends to hit three main targets. The skin often develops a widespread rash that can cover large areas of the body and, in severe cases, progress to blistering. The gut produces nausea, cramping, and diarrhea that can become severe enough to cause dangerous fluid loss. Liver involvement shows up as jaundice and abnormal liver function. Doctors grade acute GVHD on a scale from 1 to 4 based on how much of the body is affected and how severely each organ is damaged.
Chronic GVHD behaves more like an autoimmune disease and can affect a wider range of organs. It often causes excessive scarring and tissue tightening in the skin, lungs, and mucous membranes. Dry eyes are the most frequent complication of chronic GVHD, occurring in 40% to 76% of patients, and severity tends to track with how serious the overall disease is. Lung involvement can cause a condition where the small airways become permanently narrowed, leading to progressive shortness of breath. The mouth, joints, and muscles can also be affected.
Who Gets GVHD
GVHD only occurs after allogeneic transplants, meaning transplants using cells from another person. It does not happen with autologous transplants, where patients receive their own stored stem cells back. Reported rates of acute GVHD range from about 9% to 32% of allogeneic transplant recipients, while chronic GVHD rates range from 10% to 43%.
The single biggest risk factor is how well the donor and recipient are genetically matched. Every person carries a set of surface proteins on their cells (called HLA markers) that act like an immune fingerprint. The closer the match between donor and recipient HLA markers, the lower the risk. A large analysis of over 10,000 transplants confirmed that HLA matching significantly affects both GVHD risk and survival. Siblings are often the best match, but even matched unrelated donors carry some risk because minor genetic differences still exist.
Other factors matter too. Older donors are associated with worse outcomes. The source of stem cells plays a role: cells collected from peripheral blood (drawn from the arm after stimulation with growth factors) carry a different risk profile than cells harvested directly from bone marrow. Sex mismatches between donor and recipient, particularly a female donor to a male recipient, can also increase risk.
Prevention After Transplant
Nearly all allogeneic transplant recipients receive preventive immune-suppressing medications starting around the time of their transplant. The most common approach combines two drugs: one that suppresses T-cell activity (typically cyclosporine or tacrolimus, started a few days before the transplant) and a second agent given in short doses during the first week or two after transplant. A survey of European transplant centers found that about 61% used this combination approach, though there is no single universal standard, and protocols vary between centers.
These medications work by dampening the donor immune cells before they have a chance to mount a full attack against the recipient’s tissues. The trade-off is that suppressing the immune system also increases the risk of infection and can reduce the beneficial “graft-versus-tumor” effect, where donor immune cells help eliminate any remaining cancer cells. Transplant teams constantly balance these competing risks.
Treatment Options
When GVHD develops despite preventive measures, first-line treatment typically involves steroids to broadly suppress the immune response. For many patients, this controls the disease. But a significant portion of patients don’t respond adequately to steroids, and this group historically had limited options.
That picture has changed substantially in the past decade. Four newer drugs have received FDA approval specifically for chronic GVHD, each targeting different parts of the immune signaling pathways that drive the disease. These medications represent a shift toward more precise treatments that interrupt specific immune processes rather than suppressing the entire immune system. For patients whose GVHD doesn’t respond to steroids, these newer options have improved the chances of getting the disease under control.
Living With Chronic GVHD
Chronic GVHD can become a long-term condition that affects daily life in ways that extend well beyond the transplant itself. Dry eyes may require frequent use of lubricating drops and ongoing monitoring to prevent corneal damage. Skin tightening can limit range of motion and require physical therapy. Mouth dryness and sensitivity can make eating uncomfortable and increase the risk of dental problems.
Lung involvement is one of the more serious complications. When the small airways become scarred and narrowed, the damage is generally not reversible, making early detection through regular breathing tests important. Chronic GVHD features a pattern of excessive scarring and tissue narrowing across multiple organ systems, which is why it often resembles autoimmune conditions like scleroderma or lupus more than a typical transplant complication.
The severity varies enormously from person to person. Some patients experience mild skin or eye symptoms that are manageable with topical treatments, while others develop multi-organ involvement that requires years of systemic therapy. The overall trajectory depends on how many organs are involved, how quickly the disease responds to treatment, and whether it can eventually be controlled enough to taper immune-suppressing medications.