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Neither Metformin nor Ursodeoxycholic Acid Effectively Treats Postacute Sequelae of COVID-19 : A Randomized Clinical Trial

Lim SY, Lee J, Chang E, Kwon JS, Jang CY, Seo Y, Park JJ, Na SH et al.

Annals of internal medicine, 2026

666 participants · 1 citation

Abstract

Background: There is no proven treatment to alleviate symptoms of postacute sequelae of SARS-CoV-2 infection (PASC), despite its substantial public health burden.

Objective: To evaluate the efficacy of metformin and ursodeoxycholic acid (UDCA) in improving PASC symptoms in adults.

Design: Double-blind, placebo-controlled, randomized clinical trial. (Clinical Research Information Service: KCT0009342).

Setting: Two tertiary hospitals in South Korea, July 2024 to April 2025.

Participants: Of 666 adults screened, 396 with a PASC index score of 12 or greater were randomly assigned.

Intervention: Oral metformin (uptitrated to 1500 mg/d), UDCA (900 mg once daily), or double placebo for 14 days (1:1:1).

Measurements: Proportion of participants achieving PASC recovery (index score <12) at 8 weeks.

Results: Among 396 randomized participants (median age, 36 years [IQR, 28 to 49 years]; 72% women), 132 received metformin, 132 received UDCA, and 132 received placebo. The mean interval from SARS-CoV-2 infection was 9.8 months (SD, 7.5). The mean baseline PASC score was 19.3 (SD, 5.7). Recovery occurred in 63.6% (84 of 132) with metformin, 68.2% (90 of 132) with UDCA, and 68.2% (90 of 132) with placebo. Mean changes in PASC scores from baseline to week 8 were -10.05 (95% CI, -11.35 to -8.76) with metformin and -10.62 (CI, -11.79 to -9.45) with UDCA, compared with -10.43 (CI, -11.69 to -9.18) with placebo.

Limitation: Findings may not be generalizable to patients with more severe or…

How strong is the evidence?

Evidence Hub reads this as a randomized trial, done in people. Its evidence level is 2 of 5 (High · randomized trial). Randomized trials of a reasonable size are the strongest single-study design. Reported size: 666 participants or records.

How the five levels of evidence work. The level is assigned automatically from the abstract and can be wrong, so check the paper.

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