Background Elsberg syndrome (ES) is an acute‐onset lumbosacral radiculitis with myelitis caused by a herpes virus infection. Case Presentation We present a case of a 77‐year‐old woman who was admitted with urinary retention prior to genital rash. The patient was diagnosed with ES and treated with intravenous acyclovir 250 mg every 8 h for 1 week. Conclusion Physicians should consider ES in patients with voiding dysfunction, as preceding neurological symptoms may lead to a misdiagnosis. Considering the adverse effects of the antiviral drug, its dosage should be according to the causative virus of the ES as well as the patient's age and medical history.