• reactions to medications
• problems breathing

Chemotherapy given prior to bone marrow transplant (conditioning) can cause significant toxicity, such as mouth sores, diarrhea, liver damage, or lung damage. While waiting for bone marrow to grow, the patient is at high risk for infection.

The major problem with bone marrow transplants (when the marrow comes from a donor, not the patient) is graft-versus-host disease. The transplanted healthy bone marrow cells may attack the patient's cells as though they were foreign organisms. In this case, drugs to suppress the immune system must be taken, but this also decreases the body's ability to fight infections.