A Diphenhydramine Overdose Mimicking Encephalitis, Complicated by Acute Kidney Injury Associated with Anticholinergic Urinary Retention: A Case Report
Abstract
A 26-year-old man presented with fever, an altered consciousness, tremor, mydriasis, tachycardia, and a dry oral mucosa and was empirically treated for suspected encephalitis. A rapid neurological improvement and anticholinergic findings prompted the reconsideration of intoxication. A family assisted room search revealed empty over-the-counter medication bottles, and he later reported ingesting 2.4 g of diphenhydramine at once. Acute kidney injury developed in association with diphenhydramine-induced urinary retention, and his urine output and renal function improved after catheterization. In encephalitis-like presentations with systemic anticholinergic signs, a diphenhydramine overdose should be considered, a collateral medication history should be sought, and urinary tract obstruction should be assessed if the renal function worsens.
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BibTeX
@article{inoue2026diphenhydramine,
title = {{A Diphenhydramine Overdose Mimicking Encephalitis, Complicated by Acute Kidney Injury Associated with Anticholinergic Urinary Retention: A Case Report}},
author = {Hiroyasu Inoue and Erina Miwa and Yuta Madokoro and Takahisa Kasugai and Shumpei Madokoro and Yuto Uchida and Shoji Kawashima and Masahiro Oomura and Noriyuki Matsukawa},
journal = {Internal Medicine},
year = {2026},
month = oct,
doi = {10.2169/internalmedicine.7976-26},
url = {https://www.jstage.jst.go.jp/article/internalmedicine/advpub/0/advpub_7976-26/_article},
note = {CC BY-NC-ND},
}
RIS
TY - JOUR
TI - A Diphenhydramine Overdose Mimicking Encephalitis, Complicated by Acute Kidney Injury Associated with Anticholinergic Urinary Retention: A Case Report
AU - Hiroyasu Inoue
AU - Erina Miwa
AU - Yuta Madokoro
AU - Takahisa Kasugai
AU - Shumpei Madokoro
AU - Yuto Uchida
AU - Shoji Kawashima
AU - Masahiro Oomura
AU - Noriyuki Matsukawa
PY - 2026
DA - 2026/10/22
JO - Internal Medicine
DO - 10.2169/internalmedicine.7976-26
UR - https://www.jstage.jst.go.jp/article/internalmedicine/advpub/0/advpub_7976-26/_article
AB - A 26-year-old man presented with fever, an altered consciousness, tremor, mydriasis, tachycardia, and a dry oral mucosa and was empirically treated for suspected encephalitis. A rapid neurological improvement and anticholinergic findings prompted the reconsideration of intoxication. A family assisted room search revealed empty over-the-counter medication bottles, and he later reported ingesting 2.4 g of diphenhydramine at once. Acute kidney injury developed in association with diphenhydramine-induced urinary retention, and his urine output and renal function improved after catheterization. In encephalitis-like presentations with systemic anticholinergic signs, a diphenhydramine overdose should be considered, a collateral medication history should be sought, and urinary tract obstruction should be assessed if the renal function worsens.
SN - 1349-7235
SN - 0918-2918
ER -