Impact of combined plant extracts on long COVID: An exploratory randomized controlled trial.

BACKGROUND

Long COVID have posed a global health burden since the COVID-19 pandemic. This study aimed to evaluate the efficacy and safety of a combined plant extract (CPE) formulation, containing Citrus aurantifolia, Tiliacora triandra, Cannabis sativa, Alpinia galanga, and Piper nigrum, in participants with long COVID. A newly developed long COVID symptom questionnaire was used to evaluate outcomes.

METHODS

This randomized, double-blinded, placebo-controlled trial was conducted at the College of Pharmacy, Rangsit University, Thailand. Participants were randomly assigned to receive either a CPE supplement (4500 mg/day) or a placebo for 7 days. Primary outcomes were changes in C-reactive protein (CRP) levels and the total symptom score (ranging from 0 to 57 points). Secondary outcomes included full recovery/improvement of long COVID symptoms, health-related quality of life (HRQOL), and adverse events.

RESULTS

A total of 66 participants were enrolled, with 33 in each group. The CPE supplement did not significantly reduce CRP levels, with a median difference (MD) (95 % CI) of -0.05 (-0.49, 0.39) mg/L compared to placebo. However, the CPE group showed a reduction in the total symptom score [MD (95 % CI) of -4.00 (-7.58, -0.42)], and a reduction in overall moderate to severe symptoms [RR (95 % CI) of 0.57 (0.35, 0.91)], moderate to severe fatigue [RR (95 % CI) of 0.25 (0.08, 0.81)], and moderate to severe post-exertional malaise (PEM) [RR (95 % CI) of 0.35 (0.16, 0.78)]. Changes in HRQOL scores did not differ significantly between groups. Adverse events were mostly mild and resolved by the end of the follow-up period.

CONCLUSIONS

Our study suggests potential benefits of the CPE in alleviating moderate to severe long COVID symptoms, particularly fatigue and PEM, with an acceptable safety profile. However, larger-scale trials are necessary to validate these findings, and assessing the reliability of the long COVID symptom questionnaire is essential before its application in future studies.

TRIAL REGISTRATION NUMBER

TCTR20230131004 (Registration date: 2023-01-31, Thai Clinical Trials Registry).

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