Diphenhydramine–Sodium Bicarbonate Combo May Improve Vertigo Relief: JAMA
Taiwan: A new study has revealed that using diphenhydramine along with sodium bicarbonate provides better symptom relief in vertigo patients than diphenhydramine alone and reduces the need for additional treatment.
The randomized clinical trial, published in JAMA Network Open by Chien-Yu Chi from the Department of Emergency Medicine, National Taiwan University Hospital Yunlin Branch, Douliu, Taiwan, and colleagues, explored the comparative effectiveness of diphenhydramine, sodium bicarbonate, and their combination in patients with acute peripheral vertigo.
Intravenous diphenhydramine is a widely used treatment for vertigo but is often associated with drowsiness. Sodium bicarbonate, an alternative therapy used in some Asian countries, has been reported to relieve vertigo without causing sedation. However, direct comparisons between the two agents have been limited.
The researchers conducted a triple-arm, double-blind randomized trial at the National Taiwan University Hospital, Yunlin Branch, between January and November 2023. The study included 225 adults who presented to the emergency department with symptoms of peripheral vertigo within 24 hours of onset. Participants were randomly assigned to receive either 30 mg of intravenous diphenhydramine, 66.4 mEq (approximately 1 mEq/kg) of sodium bicarbonate, or a combination of both.
The primary endpoint was the change in vertigo severity, measured using a 10-point visual analog scale (VAS) 60 minutes after treatment. Secondary outcomes included changes in nausea, the need for rescue medications, emergency department length of stay, and side effects.
The key findings from the trial were as follows:
- The study included 222 participants with a mean age of 57.9 years, of whom 67.6% were women.
- Patients who received a combination of diphenhydramine and sodium bicarbonate showed significantly greater improvement in vertigo symptoms than those given diphenhydramine alone (mean VAS change −5.6 vs −4.4).
- The combination therapy group required fewer rescue treatments (17.8% vs 46.7%).
- The benefit of combination therapy was more pronounced among younger male patients without a history of vertigo.
- Sodium bicarbonate alone did not result in a statistically significant difference in symptom improvement compared with diphenhydramine (mean VAS change −5.1 vs −4.4).
- Sedation was observed more frequently in groups receiving diphenhydramine.
- Injection discomfort was more common among patients who received sodium bicarbonate.
The authors noted some limitations, including that the trial was conducted only during daytime hours due to staffing constraints and lacked a placebo arm. Additionally, the primary outcome relied on subjective patient assessments of vertigo severity, and the specific peripheral vertigo subtype was not identified.
Despite these limitations, the study provides valuable insight into a potential combination approach for managing acute peripheral vertigo. The findings indicate that combining diphenhydramine with sodium bicarbonate offers better symptom control and reduces the need for additional treatment compared with diphenhydramine alone.
The researchers emphasized the need for further studies to identify which vertigo subtypes might benefit most from sodium bicarbonate therapy and to explore the mechanisms underlying its efficacy.
Reference:
Chi C, Chen Y, Cheng M, et al. Diphenhydramine, Sodium Bicarbonate, or Combination for Acute Peripheral Vertigo: A Randomized Clinical Trial. JAMA Netw Open. 2025;8(11):e2541472. doi:10.1001/jamanetworkopen.2025.41472
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