Sawyer, M H, Webb, D E, Balow, J E et al. · The American journal of medicine · 1988 · DOI
This study describes four patients with ME/CFS who developed sudden kidney problems after receiving high-dose acyclovir (an antiviral medication) intravenously. Doctors found needle-shaped crystals in the urine and determined that the medication itself was damaging the kidneys. The good news is that lower doses of acyclovir given by mouth did not cause the same problems.
ME/CFS patients and clinicians need to understand that high-dose IV acyclovir—sometimes used experimentally in ME/CFS—carries significant nephrotoxicity risk. This report documents a concrete mechanism of harm and practical prevention strategies, directly informing safer treatment protocols for ME/CFS populations if acyclovir is considered.
This study does not prove that all ME/CFS patients are at equal risk for acyclovir nephrotoxicity, nor does it establish the prevalence of this complication across the broader ME/CFS population. The case series format cannot determine whether underlying ME/CFS pathology increases kidney vulnerability to acyclovir compared to healthy controls. It also does not establish whether oral acyclovir at higher doses would remain safe.
About the PEM badge: “PEM required” means post-exertional malaise was an explicit required diagnostic criterion for participant inclusion in this study — not that PEM was studied, observed, or discussed. Studies using criteria that do not require PEM (e.g. Fukuda, Oxford) are tagged “PEM not required”. How the atlas works →
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