Treating aplastic anemia depends on how severe the condition is and how old you are. For severe cases in patients under 40 with a matched sibling donor, a stem cell transplant offers the best chance of a cure, with five-year survival around 78% overall and as high as 86% for patients under 20. For everyone else, the primary approach is immunosuppressive therapy, often combined with a drug that stimulates blood cell production. Milder cases may only need monitoring and supportive care like transfusions.
How Severity Shapes the Treatment Plan
Aplastic anemia is classified as moderate, severe, or very severe based on blood counts and bone marrow activity. Severe aplastic anemia requires at least two of the following: a very low white blood cell count (neutrophils below 500 per microliter), platelets below 20,000 per microliter, or an extremely low number of young red blood cells. Very severe disease means the neutrophil count drops below 200 per microliter, which puts you at immediate risk for life-threatening infections.
Moderate aplastic anemia, where blood counts are low but don’t meet those thresholds, is typically managed with close monitoring and transfusions as needed. Severe and very severe cases need treatment quickly, either a transplant or immunosuppressive therapy, because the risk of fatal infection or bleeding rises the longer counts stay critically low.
Stem Cell Transplant: The Curative Option
A stem cell transplant (also called a bone marrow transplant) replaces your damaged marrow with healthy donor cells. European guidelines recommend this as the first-line treatment for patients younger than 40 who have a matched sibling donor. The match matters enormously. When a brother or sister is a full tissue match, five-year survival reaches about 86% for patients under 20 and 82% for those aged 21 to 40. Survival drops with age: roughly 62% for patients between 41 and 60, and 57% for those over 60 with a sibling donor.
Only about 25 to 30 percent of patients have a matched sibling, so finding an alternative donor is common. A matched unrelated donor from a registry is the next best option, with two-year overall survival around 67%. Half-matched family donors (called haploidentical donors) are increasingly used when no better match exists, though two-year survival is lower at about 54%. When high-intensity conditioning regimens are used to prepare the body, outcomes between matched unrelated and half-matched donors become more comparable, with no significant differences in graft failure or survival.
For younger patients under 20 who lack a sibling donor but have urgent needs, such as recurrent serious infections, guidelines suggest considering an unrelated donor transplant if one can be found within 8 to 12 weeks. The key tradeoff with transplant is upfront risk (including graft-versus-host disease, where donor cells attack your body) in exchange for the possibility of a permanent cure.
Immunosuppressive Therapy
If you’re over 40, or younger without a matched sibling donor, the standard first treatment is immunosuppressive therapy. This approach works because most aplastic anemia is autoimmune: your immune system mistakenly destroys your own bone marrow. Suppressing that attack lets the marrow recover.
The backbone of treatment is a protein derived from horse blood that targets and depletes the immune cells causing damage, combined with a drug called cyclosporine that keeps the immune system suppressed long-term. This combination produces a blood count response in about 68% of patients within six months. A rabbit-derived version of the same protein was tested head-to-head and performed significantly worse, with only a 37% response rate at six months and lower three-year survival (76% versus 96%). Because of this, the horse-derived version remains the standard.
Treatment is given in the hospital over several days and can cause temporary side effects like fever, chills, and a drop in blood counts before things improve. Cyclosporine continues for months afterward and is tapered slowly. Stopping it too quickly raises the risk of relapse, which occurs in roughly 28% of patients within three years even with optimal treatment.
Adding a Blood Cell Stimulator
A newer addition to first-line therapy is eltrombopag, a pill that stimulates the bone marrow to produce more blood cells. When started on the same day as immunosuppressive therapy at a dose of 150 mg daily, it appears to improve response rates beyond what immunosuppression alone achieves. East Asian patients typically start at a lower dose (75 to 100 mg) due to differences in how the drug is processed.
Eltrombopag is generally continued for three to six months. If there’s no improvement after six months at the full dose, it’s stopped because of a small concern that prolonged use could promote abnormal cell changes in the marrow. Starting all three treatments on day one has become the preferred approach based on trial experience showing it was safe and effective.
Supportive Care During Treatment
Regardless of which main treatment you receive, supportive care keeps you safe while your marrow recovers. This means transfusions, infection prevention, and managing iron buildup.
Red blood cell transfusions are given when your hemoglobin drops low enough to cause symptoms like fatigue or shortness of breath. Platelet transfusions are traditionally given when counts fall below 20,000 per microliter, though some centers use a more conservative threshold of 5,000 to 10,000 for stable outpatients, transfusing only when there are signs of bleeding or fever. This more restrictive approach has been shown to be safe and allows patients to spend more time outside the hospital.
Infection is the leading cause of death in severe aplastic anemia. When your neutrophil count is extremely low, even minor bacteria or fungi can become dangerous. Antiviral medications are standard for patients on immunosuppressive therapy, started at the beginning of treatment and continued until the immune system recovers. Antifungal medications aren’t routinely prescribed but may be added if your neutrophil count stays below 500 for more than four weeks. Avoiding crowds, practicing careful hand hygiene, and steering clear of raw or undercooked foods are practical steps that reduce risk during this vulnerable period.
Iron Overload From Repeated Transfusions
Each unit of transfused red blood cells deposits iron into your body, and your body has no natural way to get rid of excess iron. Over time, this iron accumulates in the liver, heart, and other organs, potentially causing damage. Iron chelation therapy, medication that binds excess iron so your body can excrete it, is typically started once your ferritin level (a blood marker of iron stores) exceeds 1,000 micrograms per liter. Patients who need transfusions for months or years should have their ferritin checked regularly.
Long-Term Risks After Treatment
Even after successful treatment, aplastic anemia requires ongoing monitoring. About 15% of patients develop a bone marrow cancer, either myelodysplastic syndrome or acute leukemia, within 10 years. In one long-term study, 11% of patients progressed to myelodysplastic syndrome over a median of about seven years, and a small number of those went on to develop leukemia. This risk is why regular blood counts and occasional bone marrow checks remain part of follow-up care for years after initial treatment.
Relapse is also possible, particularly after immunosuppressive therapy. Some patients respond to a second round of the same treatment, while others may become candidates for a transplant at that point. The likelihood of relapse, clonal evolution, and the need for ongoing transfusions all factor into why transplant is preferred for younger patients who have a good donor match: it eliminates the diseased marrow entirely rather than suppressing the immune attack against it.