Niclosamide—A promising treatment for COVID-19

Shivani Singh, Anne Weiss, James Goodman, Marie Fisk, Spoorthy Kulkarni, Ing Lu, Joanna Gray, Rona Smith, Morten Sommer, Joseph Cheriyan*

*Corresponding author for this work

Research output: Contribution to journalReviewResearchpeer-review


Vaccines have reduced the transmission and severity of COVID-19, but there remains a paucity of efficacious treatment for drug-resistant strains and more susceptible individuals, particularly those who mount a suboptimal vaccine response, either due to underlying health conditions or concomitant therapies. Repurposing existing drugs is a timely, safe and scientifically robust method for treating pandemics, such as COVID-19. Here, we review the pharmacology and scientific rationale for repurposing niclosamide, an anti-helminth already in human use as a treatment for COVID-19. In addition, its potent antiviral activity, niclosamide has shown pleiotropic anti-inflammatory, antibacterial, bronchodilatory and anticancer effects in numerous preclinical and early clinical studies. The advantages and rationale for nebulized and intranasal formulations of niclosamide, which target the site of the primary infection in COVID-19, are reviewed. Finally, we give an overview of ongoing clinical trials investigating niclosamide as a promising candidate against SARS-CoV-2.

Original languageEnglish
JournalBritish Journal of Pharmacology
Publication statusAccepted/In press - 2022

Bibliographical note

Funding Information:
JC and RS acknowledge institutional grants from Union Therapeutics for the conduct of investigator initiated clinical trials of niclosamide. MS is a shareholder of UNION Therapeutics, and AW benefits from an employee incentive scheme. The other authors declare no conflict of interest.

Funding Information:
The PROTECT‐V trial is overseen by the NIHR Covid‐19 Understanding and Elimination‐Trials Implementation Panel (CUE‐TIP). PROTECT‐V is funded by LifeArc, Addenbrooke's Charitable Trust, Cambridge University Hospitals, and Kidney Research UK with financial contributions from Union Therapeutics for the niclosamide arm. The TACTIC‐E trial is funded by UNION Therapeutics, Denmark, as well as AstraZeneca and Evelo Biosciences with significant financial support from the NIHR Cambridge BRC. RS and JC acknowledge funding support from the NIHR Cambridge BRC. AW and MS also acknowledge support from Innovation Fund Denmark (Innovationsfonden) under grant number 0153‐00209 and The Novo Nordisk Foundation under NFF grant number NNF20CC0035580.

Funding Information:
This research was supported by the NIHR Cambridge Biomedical Research Centre, UK (BRC‐1215‐20014). The views expressed are those of the authors and not necessarily those of the NIHR or the Department of Health and Social Care. RS and JC are the Chief Investigators for the PROTECT‐V and TACTIC‐E clinical trials, respectively.

Publisher Copyright:
© 2022 The Authors. British Journal of Pharmacology published by John Wiley & Sons Ltd on behalf of British Pharmacological Society.


  • clinical trials
  • COVID-19
  • niclosamide
  • repurposing


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