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Article

A clinical safety study of Kerra formula capsules following oral administration in healthy volunteers

Chaiwat Rerkswattavorn1, Wandee Chanprasertpinyo2, Manit Nuinoon3, Rangsan Butcha4, Phayong Thepaksorn5, Piyachat Evelyn Denbaes6, Muhammad Junaid7, Motoki Imai8, Makoto Kubo9, Hideyuki J Majima10, Katanchalee Thabsri11, Suwannee Sroisong12, Pussadee Srathong13, Suriyan Sukati14★★ Corresponding author

  1. 1School of Medicine, Walailak University Hospital, and Hematology and Transfusion Science Research Center (HTSRC), Walailak University, Nakhon Si Thammarat 80160, Thailand.
  2. 2School of Medicine, and Walailak University Hospital, Walailak University, Nakhon Si Thammarat 80160, Thailand.
  3. 3Department of Medical Technology, School of Allied Health Sciences, and Hematology and Transfusion Science Research Center (HTSRC), Walailak University, Nakhon Si Thammarat 80160, Thailand.
  4. 4Prachatipat Hospital, Pathum Thani 12130, Thailand.
  5. 5Sirindhorn College of Public Health, Trang, Faculty of Public Health and Allied Health Sciences, Praboromarajchanok Institute, Nonthaburi 11000, Thailand.
  6. 6Department of Medical Technology, Faculty of Medicine, Western University, Pathum Thani 12150, Thailand.
  7. 7Department of Pharmacy, University of Swabi, Khyber Pakhtunkhwa 23562, Pakistan.
  8. 8Department of Molecular Diagnostics, Kitasato University Graduate School of Medical Sciences, and Regenerative Medicine and Cell Design Research Facility, Kitasato University School of Allied Health Sciences, Sagamihara 252-0373, Japan.
  9. 9Regenerative Medicine and Cell Design Research Facility, Kitasato University School of Allied Health Sciences, Department of Microbiology, School of Allied Health Sciences, and Department of Environmental Microbiology, Graduate School of Medical Sciences, Kitasato University, Sagamihara 252-0373, Japan.
  10. 10School of Allied Health Sciences and Research Excellence Center for Innovation and Health Products (RECIHP), Walailak University, Nakhon Si Thammarat 80160, Thailand.
  11. 11Phra Chom Klao Hospital, Phetchaburi 76000, Thailand.
  12. 12Faculty of Nursing, Northern College, Tak 63000, Thailand, and Visiting Professor, Faculty of Health Sciences, University of Cuu Long, Vinhlong Province, Vietnam, Thailand.
  13. 13Boromarajonani College of Nursing, Nonthaburi Province, Faculty of Nursing, Praboromarajchanok Institute, Nonthaburi 11000, Thailand.
  14. 14Department of Medical Technology, School of Allied Health Sciences, and Hematology and Transfusion Science Research Center (HTSRC), Walailak University, Nakhon Si Thammarat 80160, Thailand.

CORRESPONDENCE

Suriyan Sukati

Department of Medical Technology, School of Allied Health Sciences, and Hematology and Transfusion Science Research Center (HTSRC), Walailak University, Nakhon Si Thammarat 80160, Thailand.

suriyan.su@wu.ac.th

Received: 02-07-2025; Accepted: 29-11-2025.

Volume 24, Issue 3 · pp. 3466 · PUBLISHED Jul-Sep 2026 · DOI: 10.18549/PharmPract.2026.3.3466

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ABSTRACT

Background: Kerra formula, derived from Tak-Ka-Si-La, an ancient Thai compilation, is composed of nine medicinal plants and used for its fever-reducing properties. It has been primarily employed to alleviate fever and was also used by some individuals in Thailand during COVID-19 infections. Moreover, a previous in vitro study indicated the potential of the Kerra formula to inhibit SARS-CoV-2 main protease and RNA-dependent RNA polymerase (RdRp). This study aimed to assess the safety and short-term side effects of Kerra formula capsules on 11 healthy volunteers. Methods: Two capsules of 500 mg were taken orally 4 times daily for 2 weeks. Symptoms, medical history, physical examination, and laboratory tests were examined. Parameters assessed included complete blood count, coagulation profiles, liver and renal function tests, urinalysis, inflammation markers, fasting blood sugar, and lipid profiles. Results: Comparing baseline and post-capsule results at 1, 7, and 14 days, and after a 14-day washout period, no abnormalities were found in physical examination. Moreover, no adverse reactions or statistically significant differences occurred in laboratory results. Additionally, favorable trends in blood pressure and lipid profiles suggest potential cardiovascular benefits. Conclusion: The study concludes that this protocol resulted in no deleterious effect in all volunteers, suggesting safe administration. However, further research is crucial to assess the herb’s long-term effects. In particular, its potential role in preventing or mitigating COVID-19 infection should be investigated for safety through studies in animal models, followed by clinical research in infected individuals to establish therapeutic relevance and elucidate mechanisms of action.

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    Rerkswattavorn, C., Chanprasertpinyo, W., Nuinoon, M., Butcha, R., Thepaksorn, P., Denbaes, P. E., Junaid, M., Imai, M., Kubo, M., Majima, H. J., Thabsri, K., Sroisong, S., Srathong, P., & Sukati, S. (2026). A clinical safety study of Kerra formula capsules following oral administration in healthy volunteers. Pharmacy Practice, 24(3), 3466. https://doi.org/10.18549/PharmPract.2026.3.3466