Hermetica Superfood Encyclopedia
The Short Answer
Niclosamide is an anthelmintic compound classified as a salicylamide that disrupts energy metabolism in tapeworms by uncoupling oxidative phosphorylation in parasite mitochondria. It has been a WHO Essential Medicine since 1977 for treating cestode infections and is under active investigation for antiviral and anticancer applications.
CategoryNamed Bioactive Compounds
GroupCompound
Evidence LevelModerate
Primary Keywordniclosamide benefits
Synergy Pairings3
Nicosamide — botanical close-up
Health Benefits
Origin & History
Natural habitat
Niclosamide is a synthetic anthelmintic compound (C13H8Cl2N2O4) first synthesized in 1953, produced through condensation of 5-chlorosalicylic acid and 2-chloro-4-nitroaniline. It has no natural source organism or plant origin and is manufactured as a pharmaceutical-grade compound with >96-98% purity.
“Niclosamide has no historical context in traditional medicine systems, as it is a fully synthetic compound first created in 1953. It represents modern pharmaceutical development rather than traditional medicinal knowledge.”Traditional Medicine
Scientific Research
The research dossier lacks details on specific human clinical trials, RCTs, or meta-analyses with PubMed PMIDs. While niclosamide has been approved globally since the 1960s for anthelmintic use, the pre-1980s efficacy studies establishing its use are not detailed in available literature.
Preparation & Dosage
Traditional preparation
No clinically studied dosage ranges are specified in the available research, as niclosamide is a synthetic pharmaceutical compound available in oral formulations for human anthelmintic use. Laboratory solubility is noted at 14 mg/ml in DMSO or 6 mg/ml in ethanol. Consult a healthcare provider before starting any new supplement.
Nutritional Profile
Niclosamide is a synthetic halogenated salicylanilide compound (C₁₃H₈Cl₂N₂O₄, MW 327.12 g/mol) — not a nutrient. It contains no macronutrients, vitamins, minerals, or fiber. The primary bioactive moiety is the 2',5-dichloro-4'-nitrosalicylanilide scaffold, which acts as a protonophore uncoupling oxidative phosphorylation. Standard therapeutic dose for tapeworm: 2 g single oral dose (adults). Oral bioavailability is extremely low (~10% absorbed from GI tract), which is advantageous for intestinal parasite treatment but limits systemic applications. Plasma concentrations after oral dosing rarely exceed 0.25–6 µg/mL. The compound is poorly water-soluble (~0.23 mg/L at pH 7), heavily protein-bound (>95%), and rapidly metabolized via hepatic glucuronidation. Investigational reformulations (e.g., nanoparticle encapsulation, ethanolamine salt forms) aim to improve systemic bioavailability for repurposed indications such as oncology and antiviral research.
How It Works
Mechanism of Action
Niclosamide inhibits oxidative phosphorylation in helminth mitochondria by acting as a proton carrier that dissipates the mitochondrial membrane potential, preventing ATP synthesis via ATP synthase (Complex V). In mammalian cancer and viral research contexts, it suppresses Wnt/β-catenin, mTORC1, STAT3, and NF-κB signaling pathways. Its antiviral activity against SARS-CoV involves blocking viral endosomal acidification and clathrin-mediated endocytosis, impairing viral entry.
Clinical Evidence
Niclosamide's efficacy against Taenia saginata, Taenia solium, Diphyllobothrium latum, and Hymenolepis species is well-established through multiple controlled trials conducted primarily in the 1960s–1970s, with cure rates exceeding 85–95% for adult tapeworm infections at a single oral dose of 2 g in adults. A 2004 in vitro study demonstrated inhibition of SARS-CoV replication at micromolar concentrations (IC50 ~1 µM), spurring COVID-19 trial interest. Phase II trials for COVID-19 (NCT04399356 and others) used oral niclosamide but reported limited systemic bioavailability as a significant constraint, with inconclusive efficacy outcomes. Evidence for its anticancer and metabolic applications remains preclinical, and no large-scale RCTs have confirmed clinical benefit outside parasitic infections.
Safety & Interactions
Niclosamide is generally well tolerated at the standard antiparasitic dose of 2 g orally; the most common adverse effects are mild gastrointestinal symptoms including nausea, vomiting, and abdominal discomfort, occurring in roughly 10–15% of patients. Because it is minimally absorbed from the gastrointestinal tract (bioavailability <10%), systemic toxicity and drug–drug interactions are rare at antiparasitic doses, but investigational parenteral or reformulated high-absorption formulations raise greater safety concerns. It should be used cautiously in patients with severe hepatic impairment, and safety data in pregnancy are limited, placing it in a category where benefit-risk assessment is required; animal studies have not shown teratogenicity, but controlled human data are absent. No significant interactions with common anticoagulants, antiepileptics, or CYP450 substrates have been documented at standard oral antiparasitic doses.
Synergy Stack
Hermetica Formulation Heuristic
Also Known As
2',5-dichloro-4'-nitrosalicylanilideNiclocideYomesanCestocideBAY 2353C13H8Cl2N2O42-[(2-chloro-4-nitrophenyl)carbamoyl]phenol
Frequently Asked Questions
What is niclosamide used for?
Niclosamide is primarily used as an oral antiparasitic drug to eliminate tapeworm infections including Taenia saginata (beef tapeworm), Taenia solium (pork tapeworm), and Diphyllobothrium latum (fish tapeworm). A single 2 g adult dose achieves cure rates of 85–95% by killing the parasite's scolex and segments in the intestinal lumen. It has been on the WHO Essential Medicines List since 1977 and is also under investigation for antiviral, anticancer, and metabolic disease applications.
How does niclosamide kill tapeworms?
Niclosamide kills tapeworms by acting as a mitochondrial uncoupler — it transports protons across the inner mitochondrial membrane, collapsing the electrochemical gradient required by ATP synthase to produce ATP. Without ATP, the parasite cannot maintain muscle function or cellular integrity and is digested or expelled. This mechanism is selective at antiparasitic doses because the drug is poorly absorbed in the human gut, limiting systemic exposure.
Is niclosamide effective against COVID-19?
In vitro studies published as early as 2004 showed niclosamide inhibits SARS-CoV replication at an IC50 of approximately 1 µM by blocking endosomal acidification and viral entry. However, multiple Phase II clinical trials for COVID-19 were hampered by niclosamide's extremely low oral bioavailability (<10%), meaning therapeutic plasma concentrations were difficult to achieve. As of the current evidence base, no Phase III trial has confirmed clinical efficacy for COVID-19, and it is not approved or recommended for this indication.
What is the standard dosage of niclosamide for tapeworm infection?
The standard adult dose for most tapeworm infections is 2 g (four 500 mg tablets) taken as a single dose after a light meal, with tablets chewed thoroughly or crushed before swallowing. For children weighing 11–34 kg, the recommended dose is 1 g, and for children over 34 kg, 1.5 g is typically used. For Hymenolepis nana (dwarf tapeworm), a 7-day course at 2 g/day on day one followed by 1 g/day for six days is recommended due to the parasite's autoinfective life cycle.
Does niclosamide have anticancer properties?
Preclinical studies indicate niclosamide suppresses multiple oncogenic signaling pathways including Wnt/β-catenin, STAT3, mTORC1, and Notch, which are dysregulated in colorectal, breast, prostate, and lung cancers. In vitro and mouse xenograft models have shown dose-dependent tumor growth inhibition, but these results have not translated into approved therapies. The primary barrier to clinical use in oncology is its poor oral bioavailability, and reformulation strategies (nanoparticles, prodrugs) are currently under investigation in early-phase trials.
Is niclosamide safe for children with tapeworm infections?
Niclosamide is generally considered safe for children and is approved for pediatric use in tapeworm treatment, though dosing is typically adjusted based on age and weight. The drug acts locally in the intestines with minimal systemic absorption, making it a favorable choice for younger patients compared to other antiparasitic agents. However, age-specific dosing guidelines should always be followed, and pediatric use should be supervised by a healthcare provider.
Does niclosamide interact with common medications?
Niclosamide has minimal drug interactions because it is poorly absorbed in the gastrointestinal tract and acts locally on parasites. Since it does not undergo significant hepatic metabolism, it is unlikely to inhibit or induce cytochrome P450 enzymes that would affect other medications. As with any treatment, it is advisable to inform your healthcare provider of all medications and supplements before starting niclosamide.
What does the clinical evidence show about niclosamide's effectiveness against tapeworms?
Clinical studies from the 1970s and 1980s demonstrated cure rates exceeding 90% for niclosamide in treating various tapeworm species, establishing it as a gold-standard treatment recognized by the WHO. Modern efficacy data are limited due to the drug's established status and lower incidence of tapeworm infections in developed countries, but it remains the first-line recommendation for most intestinal tapeworm infections globally. The mechanism of action—uncoupling oxidative phosphorylation in parasites—has been well-characterized and remains effective against resistant strains in regions where tapeworms are endemic.
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