Brand names: Emverm, Vermox
Drug class: Anthelmintics
VA class: AP200
CAS number: 31431-39-7

Medically reviewed by Drugs.com on Jun 1, 2023. Written by ASHP.

Introduction

Anthelmintic agent; benzimidazole derivative.^{100 107}

Uses for Mebendazole

Ascariasis

Treatment of ascariasis caused by Ascaris lumbricoides (roundworm).^{100 105 107 134} Albendazole, mebendazole and ivermectin are drugs of choice.^{105 134}

Enterobiasis

Treatment of enterobiasis caused by Enterobius vermicularis (pinworm).^{107 134} Albendazole, mebendazole, and pyrantel pamoate are drugs of choice.^{105 134}

Hookworm Infections

Treatment of intestinal hookworm infections caused by Ancylostoma duodenale or Necator americanus in single or mixed infections.^{105 107 134} Drugs of choice are albendazole, mebendazole, and pyrantel pamoate.^{105 134}

Treatment of eosinophilic enterocolitis^{† [off-label]} caused by Ancylostoma caninum (dog hookworm).¹³⁴ Treatment of choice is albendazole, mebendazole, or endoscopic removal of worms.¹³⁴

Trichuriasis

Treatment of trichuriasis caused by Trichuris trichiura (whipworm).^{100 105 107 134} Albendazole is drug of choice; mebendazole and ivermectin are alternatives.^{105 134}

Angiostrongyliasis

Has been used in conjunction with corticosteroids for treatment of eosinophilic meningitis caused by Angiostrongylus cantonensis^{† [off-label]}.^{134 152} May shorten course of infection, but not number of relapses.^{134 152} Infection usually self-limited.¹³⁴ No drug proven effective; some patients have worsened when treated.¹³⁴

Baylisascariasis

Possible alternative for treatment of baylisascariasis^{† [off-label]} caused by Baylisascaris procyonis (raccoon roundworm).^{105 134}

Albendazole is drug of choice;^{105 134 153 154} some clinicians suggest that mebendazole, levamisole (not commercially available in US), and ivermectin may be alternatives if albendazole unavailable.¹³⁴

Capillariasis

Treatment of capillariasis^{† [off-label]} caused by Capillaria philippinensis (Philippine threadworm).¹³⁴ Mebendazole is drug of choice; albendazole is an alternative.¹³⁴

Toxocariasis (Visceral Larva Migrans)

Treatment of toxocariasis^{† [off-label]} (visceral larva migrans) caused by Toxocara canis or T. cati (dog or cat roundworm).^{105 134} Albendazole and mebendazole are drugs of choice.^{105 134} Concomitant corticosteroids may be indicated in severe cases with cardiac, ocular, or CNS involvement.^{105 134} Antiparasitic treatment may not be effective for ocular larva migrans; inflammation may be reduced by corticosteroid injections; surgery may be necessary for secondary damage.¹⁰⁵

Trichinellosis

Treatment of trichinellosis^† (trichinosis) caused by Trichinella spiralis (pork worm).^{105 134} Drug of choice is albendazole; mebendazole is an alternative.^{105 134} Concomitant corticosteroids usually recommended, especially for severe disease.^{105 125 127 134} Corticosteroids alleviate symptoms of the inflammatory reaction and can be lifesaving when cardiac or CNS systems are involved.¹⁰⁵

Trichostrongyliasis

Treatment of trichostrongyliasis^† caused by Trichostrongylus.¹³⁴ Pyrantel pamoate is drug of choice; albendazole and mebendazole are alternatives.¹³⁴

Related/similar drugs

metronidazole, Flagyl, albendazole, nitazoxanide, praziquantel, pyrantel, piperazine

Mebendazole Dosage and Administration

Administration

Oral Administration

Administer orally without regard to meals.^{100 107}

Mebendazole 100-mg chewable tablets: May be chewed, swallowed whole, or crushed and mixed with food.¹⁰⁷

Mebendazole 500-mg chewable tablets: Must be chewed completely before swallowing and should not be swallowed whole.¹⁰⁰ In individuals who have difficulty chewing, place tablet on a spoon and add 2–3 mL of drinking water onto the tablet using a dosing syringe.¹⁰⁰ Within 2 minutes, tablet should absorb the water and change into a soft, semi-solid mass that can be swallowed.¹⁰⁰

Dosage

Pediatric Patients

Ascariasis (Roundworm)

Oral

Children ≥2 years of age (100-mg chewable tablets): 100 mg twice daily (morning and evening) for 3 consecutive days.^{107 134} Manufacturer recommends a second course of treatment if patient not cured 3 weeks after mebendazole treatment.¹⁰⁷

Children ≥1 year of age (500-mg chewable tablets): Single 500-mg dose.^{100 134}

Enterobiasis (Pinworm)

Oral

Children ≥2 years of age (100-mg chewable tablets): Single 100-mg dose.^{107 134} Some clinicians recommend a second 100-mg dose 2 weeks later.¹³⁴ Manufacturer recommends a second course of treatment if patient not cured 3 weeks after mebendazole treatment.¹⁰⁷

Some clinicians state consider treating all household contacts, especially when multiple or repeated symptomatic infections are occurring in the household.^{105 134}

Hookworm Infections

Intestinal Hookworm Infections

Oral

Children ≥2 years of age (100-mg chewable tablets): 100 mg twice daily (morning and evening) for 3 consecutive days.^{107 134} Manufacturer recommends a second course of treatment if patient not cured 3 weeks after mebendazole treatment.¹⁰⁷

Alternatively, single 500-mg dose has been recommended.¹³⁴

Eosinophilic Enterocolitis Caused by Ancylostoma caninum (Dog Hookworm)†

Oral

100 mg twice daily for 3 consecutive days has been recommended.¹³⁴

Trichuriasis (Whipworm)

Oral

Children ≥2 years of age (100-mg chewable tablets): 100 mg twice daily (morning and evening) for 3 consecutive days.^{107 134} Manufacturer recommends a second course of treatment if patient not cured 3 weeks after mebendazole treatment.¹⁰⁷

Children ≥1 year of age (500-mg chewable tablets): Single 500-mg dose.¹⁰⁰

Capillariasis (Philippine Threadworm)†

Oral

200 mg twice daily for 20 days has been recommended.¹³⁴

Toxocariasis (Visceral Larva Migrans Caused by Dog or Cat Roundworm)†

Oral

100–200 mg twice daily for 5 days has been recommended.¹³⁴ Optimum duration of treatment not known; some clinicians recommend up to 20 days of treatment.¹³⁴ For severe symptoms or eye involvement, some clinicians state treatment may be extended to 2–4 weeks.¹³⁴

Trichinellosis (Pork Worm)†

Oral

200–400 mg 3 times daily for 3 days followed by 400–500 mg 3 times daily for 10 days has been recommended.¹³⁴

Trichostrongyliasis†

Oral

100 mg twice daily for 3 consecutive days has been recommended.¹³⁴

Adults

Ascariasis (Roundworm)

Oral

100-mg chewable tablets: 100 mg twice daily (morning and evening) for 3 consecutive days.^{107 134} Manufacturer recommends a second course of treatment if patient not cured 3 weeks after mebendazole treatment.¹⁰⁷

500-mg chewable tablets: Single 500-mg dose.¹⁰⁰

Enterobiasis (Pinworm)

Oral

100-mg chewable tablets: Single 100-mg dose.^{107 134} Some clinicians recommend a second 100-mg dose 2 weeks later.¹³⁴ Manufacturer recommends a second course of treatment if patient not cured 3 weeks after mebendazole treatment.¹⁰⁷

Some clinicians state consider treating all household contacts, especially when multiple or repeated symptomatic infections are occurring in the household.^{105 134}

Hookworm Infections

Intestinal Hookworm Infections

Oral

100-mg chewable tablets: 100 mg twice daily (morning and evening) for 3 consecutive days.^{107 134} Manufacturer recommends a second course of treatment if patient not cured 3 weeks after mebendazole treatment.¹⁰⁷

500-mg chewable tablets: Single 500-mg dose.¹⁰⁰

Eosinophilic Enterocolitis Caused by Ancylostoma caninum (Dog Hookworm)†

Oral

100 mg twice daily for 3 consecutive days has been recommended.¹³⁴

Trichuriasis (Whipworm)

Oral

100-mg chewable tablets: 100 mg twice daily (morning and evening) for 3 consecutive days.^{107 134} Manufacturer recommends a second course of treatment if patient not cured 3 weeks after mebendazole treatment.¹⁰⁷

500-mg chewable tablets: Single 500-mg dose.¹⁰⁰

Capillariasis (Philippine Threadworm)†

Oral

200 mg twice daily for 20 days has been recommended.¹³⁴

Toxocariasis (Visceral Larva Migrans Caused by Dog or Cat Roundworm)†

Oral

100–200 mg twice daily for 5 days has been recommended.¹³⁴ Optimum duration of treatment not known; some clinicians recommend up to 20 days of treatment.¹³⁴ For severe symptoms or eye involvement, some clinicians state treatment may be extended to 2–4 weeks.¹³⁴

Trichinellosis (Pork Worm)†

Oral

200–400 mg 3 times daily for 3 days followed by 400–500 mg 3 times daily for 10 days has been recommended.¹³⁴

Trichostrongyliasis†

Oral

100 mg twice daily for 3 consecutive days has been recommended.¹³⁴

Special Populations

No special population dosage recommendations.

Cautions for Mebendazole

Contraindications

• Hypersensitivity to the drug or any ingredient in the formulation.^{100 107}

Warnings/Precautions

Sensitivity Reactions

Hypersensitivity Reactions

Hypersensitivity reactions, including anaphylactic reactions, reported rarely.^{100 107}

Rash,^{100 107 114 119 122} pruritus,^{108 114 119 122} exanthema,^{100 107} urticaria,^{100 107} angioedema,^{100 107} toxic epidermal necrolysis,^{100 107} and Stevens-Johnson syndrome^{100 107} also reported rarely.

Hematologic Effects

Neutropenia (including agranulocytosis) and/or thrombocytopenia reported, especially in patients receiving higher dosages or more prolonged treatment than usually recommended.^{100 103 107 111 113 120} Myelosuppression usually reversible following discontinuance of the drug, but death has occurred rarely.¹¹³

Decreased hemoglobin concentration and/or hematocrit,^{103 108 120} leukopenia,^{108 120} and eosinophilia¹⁰⁸ also reported rarely.

Monitor blood counts if mebendazole given using higher dosage or more prolonged duration of treatment than usually recommended.^{100 107}

Specific Populations

Pregnancy

In rats, adverse developmental effects (i.e., skeletal malformations, soft tissue malformations, decreased pup weight, embryolethality) observed when single oral dose as low as 10 mg/kg (about 0.2 times total maximum daily human dosage) was administered during period of organogenesis.^{100 107}

Published data to date regarding use in pregnant women have not indicated a clear association between mebendazole and a potential risk of major birth defects or miscarriage.^{100 107} However, these studies cannot definitely establish the absence of any mebendazole-associated risk because of methodological limitations, including recall bias, confounding factors, and, in some cases, small sample size or exclusion of first-trimester mebendazole exposures.^{100 107}

Consider that untreated soil-transmitted helminth infections in pregnancy can be associated with adverse outcomes, including maternal iron deficiency anemia, low birthweight, and neonatal and maternal death.^{100 107}

Lactation

Limited data indicate small amounts of mebendazole distributed into human milk following oral administration.^{100 107} Effects on milk production and on breast-fed infant unknown.^{100 107}

Consider benefits of breast-feeding and importance of mebendazole to the woman; also consider potential adverse effects on breast-fed child from the drug or underlying maternal condition.^{100 107}

Pediatric Use

100-mg chewable tablets: Safety and efficacy not established in children <2 years of age.¹⁰⁷

500-mg chewable tablets: Safety and efficacy not established in children <1 year of age.¹⁰⁰ Safety profile of single 500-mg chewable tablet in pediatric patients 1–16 years of age is similar to that in adults.¹⁰⁰

Seizures reported when mebendazole used in children <1 year of age.^{100 107}

Geriatric Use

Data insufficient to determine whether patients ≥65 years of age respond differently to mebendazole than younger patients.^{100 107}

Common Adverse Effects

Nausea,^{100 103 107 108 119 120} vomiting,^{100 103 107 108 120} abdominal pain,^{100 107} anorexia,^{100 107} diarrhea,^{100 107} flatulence,^{100 107} headache,^{105 108 114 116 119} rash,^{100 107} tinnitus,¹¹⁹ numbness,¹¹⁹ dizziness,^{100 105 107 108 114 116 119} fever,^{103 104 106 109 114 116 119 122} abnormal liver function tests.^{100 107}

Drug Interactions

Specific Drugs

Mebendazole Pharmacokinetics

Absorption

Bioavailability

Minimally absorbed from GI tract.^a Following oral administration, majority of dose remains in the GI tract where it exerts an anthelmintic effect locally.^{100 107}

Mebendazole 100-mg chewable tablets: Oral dosage of 100 mg twice daily for 3 consecutive days results in plasma concentrations of mebendazole or the 2-amino metabolite (the major metabolite) that are ≤30 or ≤90 ng/mL, respectively.¹⁰⁷

Mebendazole 500-mg chewable tablets: Single oral dose of 500 mg in healthy adults under fasted conditions results in peak plasma mebendazole concentration of 14 ng/mL attained within 1.5 hours.¹⁰⁰

Food

Mebendazole 100-mg chewable tablets: Administration with high-fat meal increases bioavailability of mebendazole, but effect on amount of drug remaining in GI tract not expected to be substantial.¹⁰⁷

Mebendazole 500-mg chewable tablets: Administration with high-fat meal increases bioavailability, increasing peak plasma mebendazole concentration following single oral dose of 500 mg in healthy adults to 56 ng/mL, and prolongs time to peak plasma concentration by approximately 2.5 hours.¹⁰⁰

Special Populations

Children 1–16 years of age with single or mixed infections of Trichuris trichiura and/or Ascaris lumbricoides: Following a single 500-mg chewable tablet, limited data indicate that systemic exposures in those 1–3 years of age is higher than exposures reported in adults.¹⁰⁰

Plasma concentrations of mebendazole may be increased in patients with impaired hepatic function, impaired metabolism, or impaired biliary elimination.^{100 107}

Distribution

Extent

Limited data indicate small amounts distributed into human milk following oral administration.^{100 107}

Plasma Protein Binding

90–95%.^{100 107}

Elimination

Metabolism

Extensively metabolized principally in the liver.^{100 107} Metabolized via decarboxylation to 2-amino-5(6)-benzimidazolyl phenylketone.^a

Metabolites do not have anthelmintic activity.^{100 107}

Elimination Route

<2% of an oral dose of mebendazole is excreted in urine; the remainder is excreted in feces as unchanged drug and metabolites.^{100 107}

Mebendazole and its metabolites likely undergo some degree of enterohepatic recirculation.^{100 107}

Half-life

3–6 hours.^{100 107}

Stability

Storage

Oral

Chewable Tablets

Mebendazole 100-mg chewable tablets: 20–25°C.¹⁰⁷

Mebendazole 500-mg chewable tablets: <30°C in tightly closed container.¹⁰⁰ Discard unused tablets 1 month after opening the container.¹⁰⁰

Actions and Spectrum

• Benzimidazole derivative anthelmintic agent^{100 107} structurally related to albendazole and thiabendazole (not commercially available in US).^a

• Interferes with cellular tubulin formation and causes ultrastructural degenerative changes in intestine of susceptible helminths.^{100 107} Disrupts glucose uptake and digestive and reproductive functions, leading to immobilization, inhibition of egg production, and death of the helminth.^{100 107}

• Active against certain nematodes (roundworms) pathogenic to humans, including Ancylostoma duodenale (hookworm),¹⁰⁷ Angiostrongylus cantonensis,^a Ascaris lumbricoides,^{100 107} Capillaria philippinensis (Philippine threadworm),^a Enterobius vermicularis (pinworm),¹⁰⁷ Gnathostoma spinigerum,^a Necator americanus (hookworm),¹⁰⁷ Trichinella spiralis (pork worm),^a and Trichuris trichiura (whipworm).^{100 107}

• Resistance to mebendazole may occur.^{100 107} Although clinical importance unknown, mechanism of resistance may involve changes in parasite β-tubulin protein resulting in reduced binding of the drug to β-tubulin.^{100 107}

Advice to Patients

• Advise patients that mebendazole may be taken with or without food.^{100 107}

• Inform patients taking mebendazole 100-mg chewable tablets that the tablets may be chewed, swallowed whole, or crushed and mixed with food.¹⁰⁷

• Inform patients taking mebendazole 500-mg chewable tablets that the tablet must be chewed completely before swallowing and should not be swallowed whole.¹⁰⁰ Advise those who have difficulty chewing to place tablet on a spoon and add 2–3 mL of drinking water onto tablet using a dosing syringe.¹⁰⁰ Within 2 minutes, tablet should change into a soft, semi-solid mass that can be swallowed.¹⁰⁰

• Advise patients that metronidazole and mebendazole should not be used concomitantly since serious skin reactions have been reported.^{100 107}

• Importance of informing clinicians of existing or contemplated concomitant therapy, including prescription and OTC drugs, as well as any concomitant illnesses.^{100 107}

• Importance of women informing clinicians if they are or plan to become pregnant or plan to breast-feed.^{100 107}

• Importance of informing patients of other important precautionary information.^{100 107} (See Cautions.)

Preparations

Excipients in commercially available drug preparations may have clinically important effects in some individuals; consult specific product labeling for details.

Please refer to the ASHP Drug Shortages Resource Center for information on shortages of one or more of these preparations.

Medical Disclaimer