Final answer:
The potential adverse effect of zidovudine (Retrovir) that may limit its use is bone marrow suppression, leading to conditions such as anemia and neutropenia.
Step-by-step explanation:
A patient with active HIV has been taking zidovudine (Retrovir), which is an antiretroviral medication used to treat HIV infection. One potential adverse effect that may limit the duration for which this medication can be taken is bone marrow suppression. This condition can lead to anemia and neutropenia, which are reductions in red blood cells and neutrophils respectively. This suppression results from the toxicity of zidovudine to the bone marrow, where these cells are produced. Because of the risk of developing these hematologic conditions, patients on zidovudine are closely monitored, and therapy may be modified or discontinued if significant bone marrow suppression occurs.