Mebendazol
Vermox, Ovex
Revisado por pares por Sid DajaniÚltima actualización por Michael Stewart, MRPharmSÚltima actualización 26 Mar 2023
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Carefully read and follow the directions from the pack.
Everyone in your family should be treated on the same day.
Side-effects are uncommon but may include tummy (abdominal) pain and diarrhoea.
Follow the few simple hygiene rules that will help prevent re-infection. Most importantly, wash your hands and scrub your nails after visiting the toilet and before eating meals.
De un vistazo
Mebendazole is a medicine used to treat roundworm infections, especially threadworms.
It comes as an oral liquid or chewable tablets and can be bought without a prescription.
Mebendazole works by stopping worms from absorbing sugars they need to live.
Take a second dose 14 days later to kill any newly hatched worms.
Good hygiene is important to prevent re-infection as the medicine does not kill eggs.
Common side-effects include tummy discomfort, diarrhoea, and wind.
Do not use for children under 2 years old without a doctor's advice.
About mebendazole
Tipo de medicamento | Anthelmintic |
Usado para | Treatment of roundworms (particularly threadworms) in adults and in children over 2 years of age |
También llamado | Vermox®; Ovex® |
Disponible como | Oral liquid medicine and chewable tablets |
Lombrices intestinales are worms with a long, round (tubular) body. They are parasites of humans, which means that they can live in our bodies. Oxiuros, hookworms and whipworms are all types of roundworm.
Threadworms are a relatively common type of roundworm and can be easily passed from one person to another, but they do not usually cause serious problems. They live inside the bowel for a short time - adult threadworms do not live for longer than six weeks. The female worm lays her eggs at night around an infected person's back passage. This causes irritation and an 'itchy bottom'. If the person then scratches the area it allows the tiny eggs to get under the fingernails. If the fingers are then put in the mouth - for example, during sleep - the eggs may be swallowed. The worms then develop in the gut and produce more eggs. Eggs can easily get on to bedding, carpets and towels, and into house dust. They can also get on to food and be swallowed. All this creates a cycle of re-infection.
Other types of roundworm eggs live in the soil in tropical countries. They most commonly get into the body when a person gets them on his or her hands and then transfers them to their mouth. This can lead to a cycle of infection, and any food which is handled can become contaminated. Roundworm infections can be a problem for people living in, or travelling to, a tropical country, and for those who eat contaminated food.
Mebendazole works by preventing the worms from absorbing sugars which they need to survive. This kills the worm within a few days. Although mebendazole kills adult worms, it does not kill the eggs. Because of this it is important to break the cycle of re-infection. This can be done by treating everyone living in your house at the same time (even if they do not have any symptoms), and by following the advice given in the section below called 'Getting the most from your treatment', to prevent re-infection.
Mebendazole is available on prescription. You can also buy it without a prescription in pharmacies.
Before taking mebendazole
To make sure this is the right treatment for you or your child, before taking mebendazole it is important that your doctor or pharmacist knows:
Si estás embarazada o amamantando.
If you have a baby or young child in the family. You cannot buy mebendazole for use in children under 2 years old - you will need advice from a doctor.
Si está tomando otros medicamentos. Esto incluye cualquier medicamento que esté tomando y que esté disponible para comprar sin receta, así como medicamentos herbales y complementarios.
Si alguna vez has tenido una reacción alérgica a un medicamento.
How to take mebendazole
Before you start this treatment, read the manufacturer's printed information leaflet from inside your pack. The manufacturer's leaflet will give you more information about mebendazole and a full list of the side-effects which you may experience from taking it.
Follow the dosage instructions carefully and make sure all members of your family are treated on the same day, even if they do not appear to be infected.
In the UK the most common worm infection is threadworm - this is a type of roundworm and is sometimes referred to as a pinworm. For threadworm infections, you will need to take one dose of 100 mg (one tablet or 5 ml of liquid medicine).
It is highly recommended to take a second 100 mg dose 14 days later to kill any worms that have hatched since the last treatment. This is especially important if you suspect you (or your child) may have become re-infected.
Your dose will be different to this if you are prescribed mebendazole for any other type of roundworm infection.
Mebendazole can be taken before or after food. The tablets can be chewed, crushed, or swallowed whole.
Obteniendo el máximo de tu tratamiento
Mebendazole removes roundworms, but not their eggs. Therefore, it is also important to break the cycle of re-infection which can occur - this can be done by following a few simple hygiene measures to prevent you from swallowing eggs, causing a new infection:
Wash your hands and scrub your nails with a nailbrush after every visit to the toilet, and before preparing or eating a meal.
Wear underwear or pyjamas in bed.
Have a bath or shower, immediately after waking up in the morning, to wash away any eggs that have been laid during the night.
Disinfect your toilet seat and toilet handle, and the handle on your toilet door, regularly.
Vacuum the carpets in your bedrooms every day, and wet-wipe the surfaces of your bedroom furniture.
Keep your fingernails short and clean, and avoid biting your nails or sucking your fingers.
Have a separate towel for each member of your family to use.
Change and wash your clothing and bedding frequently.
Can mebendazole cause problems?
Along with their useful effects, most medicines can cause unwanted side-effects although not everyone experiences them. The table below contains some of the ones associated with mebendazole. You will find a full list in the manufacturer's information leaflet supplied with your medicine.
Mebendazole side-effects | ¿Qué puedo hacer si experimento esto? |
Tummy (abdominal) discomfort, diarrhoea, wind | If troublesome, speak with your doctor or pharmacist |
Si experimenta otros síntomas que cree que pueden deberse a este medicamento, hable con su médico o farmacéutico.
How to store mebendazole
Mantenga todos los medicamentos fuera del alcance y la vista de los niños.
Almacenar en un lugar fresco y seco, lejos del calor y la luz directos.
Información importante sobre todos los medicamentos
Información importante sobre todos los medicamentos
Si compras algún medicamento, consulta con un farmacéutico que sea seguro tomarlo junto con tus otros medicamentos.
Nunca tome más de la dosis prescrita. Si sospecha que usted u otra persona podría haber tomado una sobredosis de este medicamento, acuda al departamento de accidentes y emergencias de su hospital local. Lleve el envase con usted, incluso si está vacío.
Si vas a someterte a una operación o tratamiento dental, informa a la persona que realiza el tratamiento sobre los medicamentos que estás tomando.
Este medicamento es para ti. Nunca lo des a otras personas, incluso si su condición parece ser la misma que la tuya.
No guardes medicamentos caducados o no deseados. Llévalos a tu farmacia local, que se encargará de desecharlos por ti.
Si tienes alguna pregunta sobre este medicamento, consulta a tu farmacéutico.
Informar efectos secundarios de un medicamento o vacuna
Si experimenta efectos secundarios, puede reportarlos en línea a través de Sitio web de Yellow Card.

¿Inseguro sobre mezclar medicamentos?
Verifica posibles interacciones entre medicamentos, suplementos y alimentos antes de tomarlos juntos.
Preguntas frecuentes
How long does mebendazole take to start working?
Mebendazole works by stopping the worms from absorbing sugars they need to survive, which typically kills the threadworm within a few days of taking the medication.
Does mebendazole kill other types of worms besides threadworms?
Yes, mebendazole is an anthelmintic medicine used for the treatment of roundworms. This includes various types such as threadworms, hookworms, and whipworms. However, threadworm (pinworm) is the most common infection in the UK, and the typical single-dose treatment described is specifically for this. Other roundworm infections may require a different dosage, which would be prescribed by a doctor.
What happens if I forget to take the second dose of mebendazole after 14 days?
The second dose of mebendazole, recommended 14 days after the first, is crucial because the initial dose only kills adult worms and not their eggs. This second dose targets any new worms that may have hatched since the first treatment, helping to break the cycle of re-infection. If you miss this dose, you risk the possibility of re-infection and the worms developing again.
Is it safe to use mebendazole if I am pregnant or breastfeeding?
If you are pregnant or breastfeeding, it is important to inform your doctor or pharmacist before taking mebendazole, as this information is crucial for them to ensure it is the right treatment for you.
Where do threadworms come from, and how do they spread?
Threadworms live inside the bowel and lay their eggs around an infected person's back passage, causing an 'itchy bottom'. When the person scratches, the eggs get under their fingernails. If these fingers then go into the mouth, the eggs can be swallowed, leading to new worms developing in the gut. Eggs can also spread to bedding, carpets, towels, house dust, and even food, creating a cycle of re-infection.
Lecturas adicionales y referencias
- Manufacturer's PIL, Vermox® 100 mg tablets; Janssen-Cilag Ltd, The electronic Medicines Compendium. Dated January 2021.
- Manufacturer's PIL, Vermox® 100 mg/5 ml oral suspension; Janssen-Cilag Ltd, The electronic Medicines Compendium. Dated January 2021.
Sobre el autorVer biografía completa

Michael Stewart, MRPharmS
Gerente de Revisión de Folletos de Medicamentos – Contratista, Farmacéutico
BPharm (Hons), MRPharmS
Michael es un farmacéutico comunitario que ejerce en Midlands y South Yorkshire con más de 20 años de experiencia asesorando sobre medicamentos y condiciones médicas. Tiene una sólida formación en capacitación en atención médica, habiendo producido e impartido cursos de formación para equipos de farmacia y personal de entornos de atención residencial, incluidas enfermeras. También ha contribuido a juntas asesoras de farmacia para la gestión de condiciones de baja gravedad en la comunidad.
Acerca del revisor

Sid Dajani
Sultan Dajani se graduó en la Escuela de Farmacia de Londres en 1994 y se convirtió en el miembro más joven elegido para el consejo de la Sociedad Real de Farmacia desde su fundación en 1842.
Historial del artículo
La información en esta página está escrita y revisada por pares por clínicos calificados.
Artículo también disponible en Inglés, Alemán, Español, Francés, Italiano, Portugués, Hindi, Hebreo, Árabe, y Sueco.
Next review due: 25 Sept 2027
26 Mar 2023 | Última versión

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