A nurse is teaching a client who is beginning highly active antiretroviral therapy (HAART) for HIV which includes zidovudine (Retrovir). The nurse should include teaching regarding which black box warning associated with this medication?

A. Tendonitis rupture: Tendonitis rupture is not associated with zidovudine (Retrovir). This adverse effect is more commonly linked to certain antibiotics, like fluoroquinolones, and not to antiretroviral medications such as zidovudine. While zidovudine does have serious side effects, tendon rupture is not one of them, so this would not be a key point to emphasize in patient teaching for this medication. B. Lactic acidosis: Lactic acidosis is a known and serious black box warning for zidovudine and other nucleoside reverse transcriptase inhibitors (NRTIs). This potentially life-threatening condition occurs when lactic acid builds up in the bloodstream, which can lead to symptoms such as fatigue, nausea, vomiting, abdominal pain, and even respiratory failure. Due to the risk of lactic acidosis, patients starting zidovudine should be educated to report any signs or symptoms promptly. Monitoring for this adverse effect is essential throughout treatment. C. Nephrotoxicity: Nephrotoxicity, or kidney toxicity, is not a major black box warning for zidovudine. While some antiretroviral medications, particularly tenofovir, have been associated with kidney damage, zidovudine is more commonly linked to hematologic toxicity (e.g., anemia and neutropenia) and lactic acidosis rather than nephrotoxicity. Although kidney function should still be monitored, nephrotoxicity is not the primary concern with zidovudine. D. Thromboembolic events: Thromboembolic events (e.g., deep vein thrombosis, pulmonary embolism) are not typically associated with zidovudine. While some antiretroviral drugs can have various cardiovascular side effects, thromboembolic events are not a significant concern specific to zidovudine. The more prominent black box warnings for zidovudine include hematologic effects (like bone marrow suppression) and lactic acidosis, not thromboembolic complications.