Yomesan

Niclosamide

Treatment option:

Medically reviewed

Last updated on 22/12/2025

This page provides general, reference-level information compiled from official medical sources. It is not a substitute for professional medical advice, diagnosis, or treatment. For decisions about your health, please consult a qualified healthcare professional.

Overview of Yomesan

Property	Description
Active ingredient	Niclosamide
Form	Oral Tablet / Chewable Tablet
Pharmacological class	Anthelmintic Agent (Cestocidal)
Origin	Synthetic Compound

Yomesan is a trade name for the established medication whose active ingredient is Niclosamide, a synthetic compound primarily classified as an anthelmintic agent. Its purpose is to address parasitic concerns by targeting and eliminating organisms within the gastrointestinal system. The foundational understanding of Yomesan is rooted in its chemical identity as a salicylanilide derivative and its specific pharmacological role as a focused anti-parasitic treatment.

What Type of Medicine is Niclosamide (Yomesan)?

Niclosamide is a specific type of anti-parasitic medication known as a cestocidal agent, meaning it is designed to kill and expel tapeworms (Cestoda). As an anthelmintic agent, it falls into the broader category of drugs used to treat helminthiasis, or infections caused by parasitic worms. The efficacy of this class of drugs against the targeted organisms supports its classification as a prominent medication for intestinal tapeworm infections. This classification ensures that Niclosamide's mechanism is uniquely tailored to the tapeworm's biological structure and metabolic needs, distinguishing it from drugs targeting other types of worms, such as roundworms (nematodes).

Composition, Origin, and Preparation of Niclosamide

The medicine is a single active ingredient product consisting only of the synthetic substance Niclosamide. The compound's chemical structure is defined as 2',5'-dichloro-4'-nitrosalicylanilide. The drug is typically presented as an oral tablet or a chewable tablet, utilizing standard solid oral excipients to ensure stability and proper delivery. This formulation allows the compound to be administered via the oral route, designed to exert its targeted effect directly within the intestinal tract where the parasites reside. The chewable form is a distinguishing characteristic that often facilitates ease of administration, particularly when prompt dissolution in the upper gastrointestinal tract is desirable.

General Purpose of This Cestocidal Agent

The primary purpose of Niclosamide is to rapidly achieve the clearance of specific parasitic tapeworms from the body by incapacitating them at a fundamental metabolic level. This objective is realized through a mechanism that involves dual actions: significantly interfering with the parasite's ability to generate cellular energy and simultaneously inhibiting the organism’s uptake of necessary glucose and nutrients. By effectively starving and debilitating the organism, including its anchoring head segment (scolex), Niclosamide serves as an effective therapeutic option for resolving these intestinal parasitic conditions. This action is a definitive approach for eliminating the source of infestation by disrupting the tapeworm’s energy supply.

What side effects are possible with Yomesan?

Possible side effects and safety information

The safety profile of Niclosamide (Yomesan) is characterized by less common adverse reactions, primarily involving the Gastrointestinal System. This pattern is consistent with the medicine’s design for low systemic absorption and its targeted action within the intestinal tract against parasitic tapeworms. The most frequently documented effects are generally mild and transitory, reflecting the drug's localized influence.

Officially Documented Adverse Reactions

Adverse effects are classified according to their frequency in regulatory documentation:

Less Common Adverse Reactions: These reactions relate predominantly to the digestive system and include abdominal or stomach cramps, nausea, vomiting, diarrhea, and loss of appetite.
Rare Adverse Reactions: Less frequently observed effects involve other physiological systems and include dizziness, drowsiness, skin rash, itching of the rectal area, and an unpleasant taste.

Serious Adverse Reactions and Safety Considerations

No serious or severe adverse events are universally categorized as such within the core safety profile reported in certain government-cited clinical reviews for the chewable tablet formulation. The safety profile is largely defined by the infrequent occurrence of the less common and rare listings described above.

Population-Specific Safety Notes

Regulatory safety information includes specific notes regarding certain patient groups:

Pediatric Population: Niclosamide has not been reported to cause different side effects or problems in children aged two years and older when used at effective doses than it does in adults.
Breastfeeding: The use of niclosamide during breastfeeding is considered to pose minimal risk to the infant.

Overall Safety Profile

The official risk understanding is structured around the fact that most adverse reactions are confined to the gastrointestinal system due to the drug’s minimal systemic uptake. This approach allows for the clear communication of the limited risks associated with the medicine, focusing on mild, localized effects and rare systemic reactions.

Overdose and Emergency Response

Overdose and When to Seek Help

The official regulatory profile for Yomesan (niclosamide) overdose is defined by the drug's limited systemic absorption. The active substance, niclosamide, is only slightly absorbed from the gastrointestinal tract; therefore, systemic toxic effects are not expected in the event of overdosage.

The regulatory documentation notes the absence of documented human overdose cases, meaning no specific severe or life-threatening manifestations are recorded in the official product information. No specific antidote is known or mentioned in the regulatory text.

Regulatory-Mandated Emergency Actions

Should a patient have taken a marked overdosage, immediate professional medical attention is required. The official regulatory guidance directs that the usual therapeutic measures for the treatment of poisoning must be applied for safety reasons.

Management protocols focus solely on supportive and procedural interventions.

Overdose Management Focus	Official Regulatory Statement
Systemic Risk	Toxic effects are not expected.
Primary Intervention	Symptomatic therapy.
Required Action	Apply usual therapeutic measures for poisoning.

This structure ensures that in the event of a marked overdosage, medical professionals will implement standardized poisoning management protocols, aligning with the official documentation that prioritizes procedural safety measures.

Therapeutic Uses of Yomesan

Quick Facts

Primary Use: Treatment of cestodiasis (tapeworm infections).
Conditions: May help address infections caused by beef tapeworm (Taenia saginata).
Additional Uses: May be used in the management of infections caused by fish or broad tapeworm (Diphyllobothrium latum) and dwarf tapeworm (Hymenolepis nana).

What Yomesan Treats: Main Uses and Benefits

Yomesan (niclosamide) is a medication utilized in the health management of specific parasitic worm infections. The primary use is in the treatment of cestodiasis, which refers to infections caused by various species of tapeworm.

This medication is frequently prescribed to help address infections involving the common beef tapeworm (Taenia saginata), and it is also used for the management of infections caused by the fish or broad tapeworm (Diphyllobothrium latum). Furthermore, Yomesan may be administered for the treatment of dwarf tapeworm (Hymenolepis nana) infections. Its therapeutic function is limited to addressing tapeworms and is not effective against other types of parasitic worms, such as pinworms or roundworms. The use of niclosamide as a treatment for tapeworm infections is widely utilized, and it remains a treatment option determined by a qualified healthcare professional. Treatment with this agent works to support the eventual elimination of the parasite from the body.

Eligibility and Restrictions for Use

Who Can and Cannot Use Yomesan?

The population eligibility for Yomesan (Niclosamide) is broadly defined by regulatory authorities due to its minimal systemic absorption and localized action within the gastrointestinal tract. This profile permits use across a wide range of patient groups.

Eligibility Restrictions and Contraindications

The primary restriction on Niclosamide use is a contraindication for patients with known hypersensitivity or an allergic reaction to the active substance or any component of the formulation.

Population Group	Eligibility Status (Regulatory Basis)
Adults & Children	Permitted. Use is established across all age groups, including infants (children under 2 years), though pediatric administration is conditional on age and body weight.
Pregnancy	Permitted. No contra-indication is documented in authoritative guidelines.
Lactation/Breastfeeding	Permitted. No contra-indication is documented due to the drug’s minimal systemic absorption.
Hepatic or Renal Impairment	Permitted. No specific restriction or dosage adjustment is commonly documented.
Geriatric Patients	Permitted, though specific comparative data in this population is generally considered not fully established.

Regulatory documentation confirms that the medicine is not suitable for conditions requiring systemic absorption, as its intended therapeutic scope is limited to the intestinal lumen.

What should I know about interactions with other medicines?

Interaction Scope

The official interaction profile of Yomesan (niclosamide) is primarily focused on substances that impact its limited absorption from the gastrointestinal tract.

Medicinal Product Categories with Documented Interactions
Alcohol-containing beverages (Substance Category)
Food (Ingested Substance Category)

Specific Interacting Medicines: None are explicitly listed in the official regulatory texts.

Mechanistic Basis of Interactions:

Enhanced absorption: Co-administration with alcohol may lead to enhanced systemic exposure due to the solubility of niclosamide in alcohol.
Additive Central Nervous System (CNS) effect: Consumption of alcohol may contribute to an additive pharmacodynamic effect, increasing the risk of CNS reactions.

Timing-based Interaction Rules:

Alcohol: Niclosamide must not be taken together with alcohol-containing beverages.
Food Effect: Systemic exposure is documented to be approximately two-fold higher when the medicine is administered with food.

Population-specific Interaction Notes:

Hepatic Impairment: No dosing adjustments are required, as the medicine's minimal systemic absorption ensures it does not significantly affect hepatic function.

Interaction Classifications

Interaction Severity Classification: Prohibited (for alcohol co-consumption) and Clinically Significant (Alcohol interaction).

Regulatory Basis: Official prescribing information (SmPC/Labeling).

Interaction-Context Constraints: The limited systemic absorption of niclosamide restricts the potential for drug-drug interactions via metabolic enzymes (e.g., CYP) or transporters.

Resulting Interaction Structure

The regulatory profile prohibits the concurrent consumption of alcohol-containing beverages due to a documented interaction that leads to enhanced absorption and a resulting additive pharmacodynamic effect, which can cause impairment. The official documentation also notes that the medicine’s limited absorption means no dosing adjustment is necessary in hepatic impairment. Niclosamide is not documented to have specific systemic interactions with other medicines involving CYP enzymes or drug transporters.

Mechanism of Action

Targeted Disruption of Parasite Energy Metabolism

The primary mechanism involves Niclosamide acting as a protonophore to uncouple oxidative phosphorylation within the tapeworm's mitochondria. This action directly halts the parasite's ability to synthesize ATP (cellular energy), leading to a rapid and massive energy deficit. This core mechanistic domain is complemented by the drug's effect on glucose uptake transporters, which inhibits the parasite from absorbing external nutrients, further contributing to the energy deficit.

Incapacitation and Detachment via Scolex Paralysis

The rapid cessation of ATP production causes the tapeworm to lose capacity for active movement and cellular maintenance. This energy crisis results in the muscular paralysis of the tapeworm's body segments and, critically, the scolex (head). By disabling the scolex, the drug prevents the parasite from maintaining its adherence to the intestinal wall, facilitating its loss of function and subsequent expulsion from the gastrointestinal tract via normal intestinal peristalsis.

Intraluminal Mechanism and Physiological Constraint

The drug's mechanism is strictly confined to the intestinal lumen, or interior, because Niclosamide is only minimally absorbed into the host's bloodstream. This physiological constraint means the drug exerts a highly concentrated, local effect on the residing parasite. Due to this restriction, its action does not extend to parasitic stages or organisms located in host tissues or against the metabolically dormant ova (eggs).

Dosage and Administration Information

Administration Scope

The official guidelines for Niclosamide (Yomesan), available as a 500 mg chewable tablet, are based on the type of parasitic infection being managed, defining the precise dose, frequency, and duration. The specified route of administration is oral.

Instruction	Official Regulatory Detail
Dosing Schedule (Adults)	Beef, Pork, and Fish Tapeworms (T. saginata, T. solium, D. latum): 2 grams as a single dose. Dwarf Tapeworm (H. nana): 2 grams on Day 1, followed by 1 gram once daily for the next six days.
Preparation and Intake	The tablet must be thoroughly chewed or crushed to a fine powder before being swallowed with a small amount of water. Administration is often advised after a light meal to mitigate potential stomach discomfort.
Age-Group Rules	Pediatric dosing is weight-based and follows distinct regimens. For children over 6 years, the dose is similar to the adult dose but may be adjusted for weight. For children 2 to 6 years, the dose is reduced.
Missed-Dose Rules	If a dose is missed in the 7-day course, it should be taken as soon as possible, or skipped if it is almost time for the next scheduled dose; doubling doses is not recommended.

Resulting Procedural Structure

Official Step Sequence:

The prescribed number of tablets is counted to match the required total dosage.
The tablet(s) must be chewed thoroughly or crushed completely into a fine powder.
The prepared dose is swallowed with water, ideally after a light meal.
The regimen is completed either as a single treatment course or continued once daily for seven total days, based on the type of tapeworm.

Connection to the overall use protocol: The official instructions define the use of Niclosamide as a rapid, course-based treatment delivered via the oral route. The requirement to chew or crush the tablet is a critical procedural step designed to ensure the active compound is released for its targeted action within the gastrointestinal tract.

Recent Clinical Evidence

Research Evidence / Overview of Studies for Yomesan (Niclosamide)

Evidence for Use in Treating Tapeworm Infections (Cestodiasis)

Niclosamide was studied for tapeworm infections, a condition known as cestodiasis. This includes studies exploring its application for common tapeworms such as the beef tapeworm (Taenia saginata), the fish or broad tapeworm (Diphyllobothrium latum), and the dwarf tapeworm (Hymenolepis nana). The evidence base includes historical Randomized Controlled Trials (RCTs) and comparative clinical studies. Research explored the outcomes in individuals evaluated in studies for these common tapeworms. Studies monitored outcomes such as the parasitological cure rate, which involves checking for the absence of the tapeworm's head segment and eggs in stool samples, and outcomes related to physical discomfort or other associated symptoms.

Consistency of Findings and Regulatory View

Many of the findings describe patterns observed in the studies related to parasite clearance. Niclosamide was studied for this purpose and is referenced in guidance by intergovernmental agencies like the World Health Organization (WHO). The data show patterns related to parasite clearance during defined time intervals. Systematic reviews and meta-analyses have contributed to the broader evidence landscape, summarizing this collection of historical data and describing how patients reported their experience within these trial settings.

Long-term Follow-up and Durability of Study Outcomes

The clinical research available for Niclosamide was evaluated in studies where the follow-up durations were limited. Most key investigations monitored the results for an intermediate-term period, often spanning only 1 to 3 months after the medication was observed in patients. This short observation window was studied for confirming the initial findings. Consequently, long-term effects are not fully established, and there is limited information for long-term outcomes regarding the durability of the initial parasite clearance or patterns of recurrence. It is not yet clear whether studies followed patients years after treatment.

Evidence in Different Populations

Research explored the use of Niclosamide in both adults and children who were evaluated in studies for tapeworm infections. The results apply only to the populations studied, meaning the observed findings describe group patterns, not personal outcomes. For other specific groups, such as individuals with multiple existing health issues (comorbidities), or those with certain disease severity levels, the data for certain groups remain limited. Comparative evidence is lacking for these specialized populations, and subgroup findings are uncertain, as many studies did not specifically isolate these groups for detailed analysis.

Key Research Gaps and Uncertainties

One significant limitation is the limited modern comparative evidence; much of the evidence cited by regulators is derived from settings with varying symptom burdens in older research. Comparative evidence is lacking that directly places Niclosamide against every newer anthelmintic agent currently in use. Therefore, the evidence quality varies across studies, and the overall research highlights what is known — and what is still uncertain — about this medication.

Key Studies & References

Frequently Asked Questions (FAQ)

Common questions about Yomesan (FAQ)

Q: How long does it usually take for Yomesan to start working?

A: Official descriptions of the medicine’s mechanism indicate that it acts quickly by killing tapeworms on contact within the intestinal tract. The medicine’s action leads to the subsequent passage of the killed worms in the stool, which is described as completing the therapeutic effect.

Q: Is it okay to drive or operate machinery while taking Yomesan?

A: Official safety information reports dizziness and drowsiness as rare side effects of this medicine. Regulatory information describes these reported effects, which may affect attention or coordination when driving or operating machinery.

Q: Do studies suggest Yomesan works better on an empty stomach?

A: Patient guidelines state that the medicine may be taken on an empty stomach or after a light meal. The instruction to take it after a light meal is often provided to help reduce the potential for stomach discomfort, but regulatory information indicates that administration may occur either way.

Q: What is the purpose of the 'day of treatment' mentioned with Yomesan?

A: The duration of treatment with this medicine is defined by the specific type of tapeworm infection being addressed. Regulatory guidance prescribes a regimen that is typically either a single dose or a course lasting several days, depending on the particular parasite.

Q: Does Yomesan cause weight gain or loss?

A: Official safety profiles list loss of appetite as a less common adverse reaction. There are no definitive statements in the regulatory summaries regarding overall changes in body weight (gain or loss) linked to the medicine.

Q: Is it normal to see changes in stool after starting Yomesan?

A: Official descriptions of the medicine's action state that the killed worms are then passed in the stool as part of the body's normal process.

Q: Do I need a follow-up appointment after taking Yomesan?

A: Regulatory patient guidance emphasizes the importance of having your doctor check your progress at regular visits after treatment to confirm that the infection is completely cleared.

Q: Can I stop taking Yomesan if I feel better?

A: Official guidance for course-based treatment emphasizes that the full time prescribed should be completed. Official guidance emphasizes this based on the stated risk that stopping the prescribed course too soon may risk the infection returning.

Q: Is there a generic version of Yomesan available?

A: The medicine's active ingredient is Niclosamide. While one brand name (Niclocide) was historically withdrawn in some regions, the medicine is available under its generic name, Niclosamide, in various parts of the world.

Q: Does Yomesan interact with common pain relievers like ibuprofen?

A: Regulatory documents note that the potential for typical drug-drug interactions is limited because this medicine is minimally absorbed into the bloodstream. Specific systemic interactions with common pain relievers are generally not documented in the official texts.

Q: Are there any specific foods or drinks to avoid while taking Yomesan?

A: The only substance specifically and strictly prohibited in regulatory documents is alcohol-containing beverages, due to the potential for enhanced absorption of the medicine and increased risk of side effects. Regulatory documents do not mention other special diets or food restrictions.

Q: Does the time of day matter when taking Yomesan?

A: Official guidance emphasizes that the medicine should be taken at a time relative to meals (e.g., after a light meal or on an empty stomach). For regimens that last multiple days, taking the dose around the same time each day is typically noted to help maintain the scheduled course.

Q: How is Yomesan usually packaged (e.g., tablet, capsule)?

A: According to official product descriptions, the medicine is generally manufactured as a chewable tablet or an oral tablet for administration. The chewable form is a distinguishing characteristic that facilitates dissolution in the digestive tract.

Q: Do I need to change my diet while on Yomesan?

A: Official patient information states that no special diets or additional preparation steps are mentioned in relation to taking the medicine.

Q: Are there any long-term side effects associated with Yomesan?

A: Official research overviews indicate that most key investigations monitored results for a limited period after treatment. Consequently, data for long-term outcomes are limited, and long-term effects are not fully established.

Q: Is Yomesan a controlled substance?

A: Niclosamide is not currently designated as a controlled substance under the Controlled Substances Act or comparable international regulatory frameworks.

Q: Can people with heart conditions use Yomesan?

A: Regulatory contraindication lists generally only cite known hypersensitivity (allergic reaction) to the medicine or any component as a restriction. There are no specific restrictions or contraindications documented in official guidelines for individuals with heart conditions.

How should Yomesan be stored and disposed of?

How to Store and Dispose of Yomesan (Niclosamide)

Storage Requirements

Yomesan tablets must be stored at room temperature, specifically between 15 C and 25 C (59 F and 77 F). The medicine must be kept in its original container, which should be tightly closed, and the product requires protection from light and moisture. For safety, it must be stored out of the sight and reach of children and should not be kept in the bathroom.

Disposal Instructions

Unused or expired Yomesan must be disposed of properly according to local requirements. The medicine must not be disposed of in wastewater or general household waste. Patients should ask a pharmacist or local waste management company for instructions on how to discard the product.

Attention! Always consult to a doctor or pharmacist before using pills or medicines.