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Antihelminthic

Mebendazole

Brand names: Vermox, Ovex

Mebendazole is an anthelmintic used most commonly for threadworm (enterobiasis) and for other intestinal worm infections such as roundworm, whipworm and hookworm.

Dosing — being independently re-sourced

ClinCalc Pro is rebuilding its dose data from primary open sources — the manufacturer SmPC (eMC), the WHO Model Formulary and other official references — under clinician review. This drug's structured dose is not yet published here. Confirm all doses against the product SmPC and your local formulary before prescribing.

US labelling (FDA)

Reference — US labelling, may differ from UK

The recommended dosage in patients one year of age and older is one VERMOX™ CHEWABLE 500 mg tablet taken as a single dose. Chew VERMOX™ CHEWABLE 500 mg tablet completely before swallowing. Do not swallow the tablet whole. For patients who have difficulty chewing the tablet, approximately 2 mL to 3 mL of drinking water can be added to a suitably sized spoon and the VERMOX™ CHEWABLE 500 mg tablet placed into the water. Within 2 minutes, the tablet absorbs the water and turns into a soft mass with semi-solid consistency, which can then be swallowed. VERMOX™ CHEWABLE 500 mg tablet can be taken without regard to food intake [see Clinical Pharmacology (12.3) ]. The recommended dosage in patients …

Source: US FDA prescribing information (openFDA / DailyMed), label dated 2021-10-05. Accessed 2026-06-12. US dosing and indications can differ from UK practice — use UK sources for prescribing decisions.

Clinical monograph

How it works

It binds to parasite tubulin and inhibits microtubule formation, impairing glucose uptake and energy metabolism in the worm, leading to its death.

Prescribing in practice

  • Use with caution and generally avoid in pregnancy, particularly the first trimester; check current prescribing references before use in pregnancy or breastfeeding.
  • For threadworm, treat all household members at the same time, as reinfection is common.
  • Combine drug treatment with hygiene measures and repeat the dose after about two weeks to cover reinfection.

Monitoring

No routine monitoring is required for single-dose threadworm treatment; for prolonged high-dose use in other infections, follow the SPC for relevant safety checks.

Counselling the patient

  • Everyone in the household should be treated together, even if they have no symptoms.
  • Alongside the medicine, wash hands and nails, launder bedclothes and nightwear, and keep nails short to prevent reinfection.
  • A second dose after about two weeks is usually advised to catch any reinfection.

Evidence & guidelines

First-line for threadworm with hygiene measures (NICE CKS threadworm).

Reference: NICE CKS; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. Monograph status: clinician-reviewed (2026-07-04).

Related

Curated clinical cross-links plus same-class fallbacks.

Pathways