Acute nausea, vomiting, myalgia, and leukocytosis following a single dose of metronidazole: A case report
- 1Boukan Hospital, Urmia University of Medical Sciences, Urmia, Iran
Abstract
Background: Metronidazole is a nitroimidazole antimicrobial commonly associated with gastrointestinal adverse effects, including nausea, vomiting, abdominal discomfort, and diarrhea. Less common but potentially serious adverse events, including neurologic toxicity and rare reports of hepatic or pancreatic injury, have also been described. This case reports acute gastrointestinal symptoms, headache, diffuse myalgia, and marked neutrophilic leukocytosis occurring soon after a single oral dose of metronidazole. The temporal association is clinically notable, but causality cannot be established from a single case.Case Presentation: A 41-year-old man with no reported chronic illness or drug allergies presented to the emergency department with severe headache, diffuse body aches and myalgia, and persistent nausea and vomiting. Approximately one hour before symptom onset, he had taken a single 250-mg oral dose of metronidazole for a dental infection and oral abscess. His vital signs were stable, and no rash, urticaria, angioedema, or respiratory symptoms were documented. Laboratory testing showed a white blood cell count of 20.0 × 10⁹/L, with neutrophils accounting for 92% of the differential. He received intravenous fluids and symptomatic treatment, including ondansetron, metoclopramide, and promethazine; ceftriaxone and clindamycin were also administered for the dental infection. Nausea and vomiting resolved approximately 20 hours after presentation, and he was discharged in good general condition. The temporal relationship raises the possibility of a metronidazole-associated adverse event, but a causal relationship and specific mechanism could not be established.Discussion: This case describes acute gastrointestinal symptoms, headache, diffuse myalgia, and marked neutrophilic leukocytosis following a single dose of metronidazole. The timing suggests a possible association, but the concurrent dental infection, absence of confirmatory allergy evaluation, and lack of serial leukocyte measurements limit causal attribution. Clinicians should assess alternative explanations and document suspected medication-related events carefully without assigning a definitive drug-allergy label on temporal association alone.
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BibTeX
@article{ebrahimirad2026acute,
title = {{Acute nausea, vomiting, myalgia, and leukocytosis following a single dose of metronidazole: A case report}},
author = {Bakhtiar Ebrahimirad and Hero Payandeh},
journal = {Journal of Preventive and Complementary Medicine},
year = {2026},
month = oct,
doi = {10.22034/jpcm.2026.582186.1326},
url = {https://doi.org/10.22034/jpcm.2026.582186.1326},
note = {CC BY-NC},
}
RIS
TY - JOUR
TI - Acute nausea, vomiting, myalgia, and leukocytosis following a single dose of metronidazole: A case report
AU - Bakhtiar Ebrahimirad
AU - Hero Payandeh
PY - 2026
DA - 2026/10/25
JO - Journal of Preventive and Complementary Medicine
DO - 10.22034/jpcm.2026.582186.1326
UR - https://doi.org/10.22034/jpcm.2026.582186.1326
AB - Background: Metronidazole is a nitroimidazole antimicrobial commonly associated with gastrointestinal adverse effects, including nausea, vomiting, abdominal discomfort, and diarrhea. Less common but potentially serious adverse events, including neurologic toxicity and rare reports of hepatic or pancreatic injury, have also been described. This case reports acute gastrointestinal symptoms, headache, diffuse myalgia, and marked neutrophilic leukocytosis occurring soon after a single oral dose of metronidazole. The temporal association is clinically notable, but causality cannot be established from a single case.Case Presentation: A 41-year-old man with no reported chronic illness or drug allergies presented to the emergency department with severe headache, diffuse body aches and myalgia, and persistent nausea and vomiting. Approximately one hour before symptom onset, he had taken a single 250-mg oral dose of metronidazole for a dental infection and oral abscess. His vital signs were stable, and no rash, urticaria, angioedema, or respiratory symptoms were documented. Laboratory testing showed a white blood cell count of 20.0 × 10⁹/L, with neutrophils accounting for 92% of the differential. He received intravenous fluids and symptomatic treatment, including ondansetron, metoclopramide, and promethazine; ceftriaxone and clindamycin were also administered for the dental infection. Nausea and vomiting resolved approximately 20 hours after presentation, and he was discharged in good general condition. The temporal relationship raises the possibility of a metronidazole-associated adverse event, but a causal relationship and specific mechanism could not be established.Discussion: This case describes acute gastrointestinal symptoms, headache, diffuse myalgia, and marked neutrophilic leukocytosis following a single dose of metronidazole. The timing suggests a possible association, but the concurrent dental infection, absence of confirmatory allergy evaluation, and lack of serial leukocyte measurements limit causal attribution. Clinicians should assess alternative explanations and document suspected medication-related events carefully without assigning a definitive drug-allergy label on temporal association alone.
SN - 3041-9700
SN - 3041-9921
ER -