From WikiProjectMed
Jump to navigation Jump to search
Trade namesNiclocide, Fenasal, Phenasal, others
  • 5-Chloro-N-(2-chloro-4-nitrophenyl)-2-hydroxybenzamide
Clinical data
Main usesTapeworm[1]
Routes of
By mouth
Defined daily dose2 grams[2]
External links
AHFS/Drugs.comMicromedex Detailed Consumer Information
Chemical and physical data
Molar mass327.12 g·mol−1
3D model (JSmol)
Melting point225 to 230 °C (437 to 446 °F)
  • Clc2cc(ccc2NC(=O)c1cc(Cl)ccc1O)[N+]([O-])=O
  • InChI=1S/C13H8Cl2N2O4/c14-7-1-4-12(18)9(5-7)13(19)16-11-3-2-8(17(20)21)6-10(11)15/h1-6,18H,(H,16,19) checkY

Niclosamide, sold under the brand name Niclocide among others, is a medication used to treat tapeworm infestations.[3] This includes diphyllobothriasis, hymenolepiasis, and taeniasis.[3] It is not effective against other worms such as pinworms or roundworms.[4] It is taken by mouth.[3]

Side effects include nausea, vomiting, abdominal pain, and itchiness.[3] It may be used during pregnancy and appears to be safe for the baby.[3] Niclosamide is in the anthelmintic family of medications.[4] It works by blocking the uptake of sugar by the worm.[5]

Niclosamide was discovered in 1958.[6] It is on the World Health Organization's List of Essential Medicines.[7] The wholesale cost in the developing world is about 0.24 USD for a course of treatment.[8] It is not commercially available in the United States.[4] It is effective in a number of other animals.[5]

Medical uses


The defined daily dose is 2 grams by mouth.[2] For T. saginata, T. solium, or D. latum the dose is 2 grams once in those over the age of six, while in those 2 to 6 years old 1 gram is used, and in those under 2 years old the dose is 500 mg.[1] For H. nana the initial dose is the same, followed by six more days of treatment at half the initial dose.[1]

Side effects

Side effects include nausea, vomiting, abdominal pain, constipation, and itchiness.[3] Rarely, dizziness, skin rash, drowsiness, perianal itching, or an unpleasant taste occur. For some of these reasons, praziquantel is a preferable and equally effective treatment for tapeworm infestation.[citation needed]

Mechanism of action

Niclosamide inhibits glucose uptake, oxidative phosphorylation, and anaerobic metabolism in the tapeworm.[9]

Other applications

Niclosamide's metabolic effects are relevant to wide ranges of organisms, and accordingly it has been applied as a control measure to organisms other than tapeworms. For example, it is an active ingredient in some formulations such as Bayluscide for killing lamprey larvae,[10][11] as a molluscide,[12] and as a general purpose piscicide in aquaculture. Niclosamide has a short half-life in water in field conditions; this makes it valuable in ridding commercial fish ponds of unwanted fish; it loses its activity soon enough to permit re-stocking within a few days of eradicating the previous population.[12] Researchers have found that niclosamide is effective in killing invasive zebra mussels in cool waters.[13]


Niclosamide is being studied in a number of types of cancer.[14] Niclosamide along with oxyclozanide, another anti-tapeworm drug, was found in a 2015 study to display "strong in vivo and in vitro activity against methicillin-resistant Staphylococcus aureus (MRSA)".[15]

Danish biotech company UNION is currently[when?] conducting a clinical study using Niclosamide in the treatment of COVID-19.[16]


  1. 1.0 1.1 1.2 "Archive copy". Archived from the original on 28 August 2021. Retrieved 1 September 2020.{{cite web}}: CS1 maint: archived copy as title (link)
  2. 2.0 2.1 "WHOCC - ATC/DDD Index". Archived from the original on 22 January 2021. Retrieved 1 September 2020.
  3. 3.0 3.1 3.2 3.3 3.4 3.5 World Health Organization (2009). Stuart MC, Kouimtzi M, Hill SR (eds.). WHO Model Formulary 2008. World Health Organization. pp. 81, 87, 591. hdl:10665/44053. ISBN 9789241547659.
  4. 4.0 4.1 4.2 "Niclosamide Advanced Patient Information -". Archived from the original on 20 December 2016. Retrieved 8 December 2016.
  5. 5.0 5.1 Riviere, Jim E.; Papich, Mark G. (13 May 2013). Veterinary Pharmacology and Therapeutics. John Wiley & Sons. p. 1096. ISBN 978-1-118-68590-7. Archived from the original on 10 September 2017.
  6. Mehlhorn, Heinz (2008). Encyclopedia of Parasitology: A-M. Springer Science & Business Media. p. 483. ISBN 9783540489948. Archived from the original on 2016-12-20.
  7. World Health Organization (2019). World Health Organization model list of essential medicines: 21st list 2019. Geneva: World Health Organization. hdl:10665/325771. WHO/MVP/EMP/IAU/2019.06. License: CC BY-NC-SA 3.0 IGO.
  8. "Niclosamide". International Drug Price Indicator Guide. Archived from the original on 10 May 201. Retrieved 1 December 2016.
  9. Weinbach EC, Garbus J (1969). "Mechanism of action of reagents that uncouple oxidative phosphorylation". Nature. 221 (5185): 1016–8. doi:10.1038/2211016a0. PMID 4180173.
  10. Boogaard, Michael A. Delivery Systems of Piscicides "Request Rejected" (PDF). Archived (PDF) from the original on 2017-06-01. Retrieved 2017-05-30.
  11. Verdel K.Dawson (2003). "Environmental Fate and Effects of the Lampricide Bayluscide: a Review". Journal of Great Lakes Research. 29 (Supplement 1): 475–492. doi:10.1016/S0380-1330(03)70509-7.
  12. 12.0 12.1 "WHO Specifications And Evaluations. For Public Health Pesticides. Niclosamide" (PDF). Archived from the original (PDF) on 2017-01-10. Retrieved 2019-08-07.
  13. "Researchers find new methods to combat invasive zebra mussels". The Minnesota Daily. Archived from the original on 2018-11-21. Retrieved 2018-11-19.
  14. "Clinical Trials Using Niclosamide". NCI. Archived from the original on 25 January 2019. Retrieved 20 March 2019.
  15. Rajamuthiah R, Fuchs BB, Conery AL, Kim W, Jayamani E, Kwon B, Ausubel FM, Mylonakis E (April 2015). Planet PJ (ed.). "Repurposing Salicylanilide Anthelmintic Drugs to Combat Drug Resistant Staphylococcus aureus". PLoS ONE. 10 (4): e0124595. doi:10.1371/journal.pone.0124595. ISSN 1932-6203. PMC 4405337. PMID 25897961.
  16. GmbH, finanzen net. "UNION Receives Approval From Danish Medicines Agency to Initiate Clinical Study With Niclosamide for Treatment of COVID-19 | Markets Insider". Archived from the original on 2020-07-04. Retrieved 2020-07-02.

External links

External sites: