Graft-versus-host disease (GVHD) is a condition where transplanted donor cells attack the recipient’s body, treating it as foreign. It occurs after an allogeneic stem cell or bone marrow transplant, where the donor is another person. Historically, roughly half of transplant recipients developed significant GVHD, but improved prevention strategies have brought that rate down to about 16% for moderate-to-severe cases in recent years.
How GVHD Develops
When you receive a stem cell transplant from a donor, their immune cells (specifically T cells) rebuild your immune system. But those donor T cells can recognize your body’s own tissues as foreign. They lock onto proteins on your cells that don’t match their own, activate, and begin multiplying. Chemical signals then guide these activated T cells out of the lymph nodes and into your organs, where they cause inflammation and tissue damage.
The three organs most commonly targeted are the skin, the liver, and the gastrointestinal (GI) tract. These tissues are particularly vulnerable because of their high exposure to the inflammatory environment that transplant conditioning creates. The damage ranges from mild skin irritation to life-threatening organ failure, depending on how aggressively the donor cells react.
Acute vs. Chronic GVHD
GVHD comes in two forms that differ not just in timing but in how they behave in the body. Acute GVHD traditionally appears within the first 100 days after transplant, though it can show up later (called late-onset acute GVHD). Chronic GVHD has no time limit and can develop months or even years after transplant. Doctors now distinguish the two forms primarily by their symptoms rather than a strict calendar cutoff.
Acute GVHD is driven by a straightforward immune attack: donor cells recognize host tissue as foreign and destroy it. Chronic GVHD is more complex, involving elements of both an immune attack on foreign tissue and autoimmunity, where the immune system begins targeting the body more broadly. Chronic GVHD can affect nearly any organ, with the skin, mouth, and eyes being the most common sites. An “overlap syndrome” exists where patients show features of both forms simultaneously.
Symptoms of Acute GVHD
Skin involvement is usually the first sign. It often starts as a rash or darkened patches of skin. Biopsy of these lesions typically shows immune cells clustered around blood vessels in the skin. In severe cases, the skin can blister or ulcerate across large areas of the body.
GI symptoms can range from persistent nausea, vomiting, loss of appetite, and abdominal pain (when the upper digestive tract is involved) to watery diarrhea that can progress to bloody diarrhea in severe cases. Weight loss is common. Liver involvement shows up as rising bilirubin levels, causing jaundice, the yellowing of the skin and eyes.
Doctors grade acute GVHD on a scale from I to IV based on how severely each organ is affected. Grade I is mild, typically limited to a skin rash. Grade IV is the most severe, involving extensive skin breakdown or severe GI disease. The grade directly influences treatment decisions and expected outcomes.
Symptoms of Chronic GVHD
Chronic GVHD resembles autoimmune conditions more than a simple transplant rejection. In the skin, it can cause thickened, tight patches similar to scleroderma, or flat, purplish lesions that look like lichen planus. The mouth may develop white plaques, painful sores, or tightening that limits how wide you can open your jaw. Dry, irritated eyes are common.
Other possible signs include narrowing of the esophagus (making swallowing difficult), joint stiffness from deep tissue scarring, and vaginal or vulvar changes in women. Certain skin and oral findings are so characteristic that they alone are enough to confirm the diagnosis without a biopsy.
Risk Factors
The single biggest factor is how closely the donor’s tissue type matches yours. A large analysis of over 10,000 transplants confirmed that mismatches in key tissue-typing genes significantly increase the risk of severe GVHD. Even a single mismatch at certain gene locations can raise the odds of developing the most dangerous grades.
Beyond tissue matching, several other variables matter. Older donor age is associated with worse outcomes. Female donors who have been pregnant at least once carry a higher risk of causing chronic GVHD in the recipient, likely because pregnancy primes the immune system to recognize foreign tissue proteins. The recipient’s own age, overall health, underlying disease, and the source of stem cells (peripheral blood vs. bone marrow) also play a role.
Prevention After Transplant
Nearly all transplant recipients receive preventive immune-suppressing medications starting before or immediately after the transplant. The most widely used combination for patients receiving intensive pre-transplant conditioning pairs two drugs: one that suppresses T cell activity (started a few days before transplant) and short courses of another that slows immune cell growth (given in the first one to two weeks after transplant). This combination has been the backbone of GVHD prevention for decades.
Other prevention strategies include drugs that deplete T cells before they can cause damage and high-dose medications given a few days after transplant to selectively eliminate the most reactive donor immune cells. The choice of prevention regimen depends on the type of transplant, the donor match, and the patient’s overall condition. The dramatic decline in GVHD rates over the past two decades, from nearly 50% to about 16% for significant cases, reflects steady improvements in these approaches.
First-Line Treatment
When GVHD develops despite preventive measures, corticosteroids are the standard first treatment. Most patients are already on immune-suppressing drugs when symptoms appear, so steroids are added on top. There is ongoing debate about dosing: some centers start with higher doses, while others use lower doses for milder presentations and reserve aggressive treatment for more severe disease. Response rates vary, and a significant number of patients do not improve adequately with steroids alone.
When Steroids Don’t Work
Steroid-refractory GVHD, where symptoms persist or worsen despite corticosteroid treatment, is one of the most challenging situations after transplant. In 2019, the FDA approved the first targeted therapy specifically for steroid-refractory acute GVHD in patients 12 and older. This medication works by blocking specific signaling pathways that drive T cell activation and inflammation.
In the clinical trial that led to approval, every patient with moderate (Grade 2) disease responded to treatment. Among those with more severe disease (Grades 3 and 4), response rates were around 40 to 45%. The most common side effects were drops in blood cell counts and infections, which are already common complications after transplant.
Long-Term Outlook
For patients who survive the first year after transplant, the long-term prognosis is generally favorable but shaped by how severe their GVHD was. Five-year survival for those who experienced severe acute GVHD (Grades III-IV) was about 77.5%, compared to nearly 84% for those with minimal or no GVHD. That gap, while statistically real, reflects the cumulative toll of prolonged immune suppression and organ damage rather than a single dramatic difference.
Survivors of severe acute GVHD carry significantly higher rates of late medical complications and report somewhat lower physical and mental functioning on quality-of-life measures. However, the actual differences in daily functioning scores, while measurable, are modest enough that many patients may not perceive them as a major change in their lives. Chronic GVHD, when it develops, tends to have a larger ongoing impact on quality of life because of its persistent, multi-organ nature and the need for prolonged treatment.