Mebendazole for worm infections

This leaflet is for parents and carers about how to use this medicine in children. Our information may differ from that provided by the manufacturers, because their information usually relates to adults. Read this leaflet carefully. Keep it somewhere safe so that you can read it again.

Name of medicine


Brand names: Vermox, Ovex

Why is it important for my child to take Mebendazole?

Children commonly pick up infections with worms that live in the intestines. It is important to take mebendazole to kill these worms. You will also need to take extra steps to prevent reinfection, described later in this leaflet.

What is Mebendazole available as?

  • Tablets: 100 mg
  • Liquid medicine: 100 mg in 5 mL

When should I give Mebendazole

Mebendazole may be given either as a single dose or twice each day for 3 days, depending on the type of worm your child is infected with. Your doctor will tell you how often to give it.

  • Once: this can be at any time of day.
  • Twice a day: this should be once in the morning and once in the evening. Ideally, these times are 10–12 hours apart, for example some time between 7 am and 8 am, and between 7 pm and 8 pm.

If you give a single dose of Mebendazole you may need another single dose two weeks later, to prevent re-infection. Your doctor will give you advice about this.

How much should I give?

Your doctor will work out the amount of Mebendazole (the dose) that is right for your child. The dose will be shown on the medicine label.

It is important that you follow your doctor’s instructions about how much to give.

How should I give Mebendazole?


  • Tablets may be swallowed with a glass of water or juice. They can also be chewed before swallowing. Your child should drink a glass of water, squash or juice after chewing and swallowing the tablet.

Liquid medicine

  • Shake the medicine well.
  • Measure out the right amount using an oral syringe or a medicine spoon. You can get these from your pharmacist. Do not use a kitchen teaspoon as it will not give the right amount.

When should the medicine start working?

The medicine should start to work straight away but it may take several days to kill all the worms. It is important that your child takes the whole course of the medicine that has been prescribed. Do not stop early.

If you gave a single dose of mebendazole your child may need another single dose two weeks later, to prevent reinfection. Your doctor will give you advice about this. 

What if my child is sick (vomits)?

  • If your child is sick less than 30 minutes after having a dose of Mebendazole, give them the same dose again.
  • If your child is sick more than 30 minutes after having a dose of Mebendazole, do not give them another dose. Wait until the next normal dose.

If your child is sick again, seek advice from your family doctor, nurse, pharmacist, or hospital. They will decide what to do based on your child’s condition and the specific medicine involved.

What if I forget to give it?

If you usually give it twice a day: If you remember up to 4 hours after you should have given a dose, give your child the missed dose. For example, if you usually give a dose at about 7am, you can give the missed dose at any time up to 11am. If you remember after that time, do not give the missed dose. Give the next dose as usual.

Never give a double dose of Mebendazole.

What if I give too much?

You are unlikely to cause harm if you give an extra dose of Mebendazole by mistake. If you are concerned that you may have given too much, contact your doctor or local NHS services (details at end of leaflet). Have the medicine or packaging with you if you telephone for advice.

Are there any possible side effects?

We use medicines to make our children better, but sometimes they have other effects that we don’t want (side effects).

Side effects you must do something about

If your child gets blistering of their skin, mouth, eyes or genitals, take them to hospital or call an ambulance straight away.

Very rarely, Mebendazole can cause seizures (fits). If your child has a seizure, telephone for an ambulance. Do not restrain your child but try to make sure that they cannot hurt themselves (e.g. put a cushion under their head and move them away from furniture).

If your child seems to bruise more easily or bleeding doesn’t stop as quickly as usual, or if their skin or whites of the eyes get a yellow tinge, contact your doctor straight away, as there may be a problem with your child’s blood or liver.

If your child gets a yellowish tinge to the skin or whites of the eyes, contact your doctor straight away, as there may be a problem with your child’s liver.

Other side-effects you need to know about

  • Your child may get stomach pain, diarrhoea or flatulence (wind). If you are worried contact your doctor.

There may sometimes be other side effects that are not listed above. If you notice anything unusual and are concerned, contact your doctor. You can report any suspected side effects to a UK safety scheme at

Can other medicines be given at the same time as Mebendazole?

  • You can give your child medicines that contain paracetamol or ibuprofen, unless your doctor has told you not to.
  • Mebendazole should not be taken with some medicines. Tell your doctor or pharmacist about any other medicines your child is taking before giving Mebendazole.

Check with your doctor or pharmacist before giving any other medicines to your child. This includes herbal and complementary medicines.

Preventing re-infection

  • Worm infections are easily spread between members of a family, and it is easy to get re-infected.
  • The worms lay eggs around the anus at night. These eggs can be transferred back to the mouth, causing re-infection.
  • All members of the family must therefore take extra care with hygiene for at least 6 weeks after the infection.
  • Wash hands thoroughly, including under the finger nails, before preparing food or eating and after using the toilet. Wear underwear in bed and wash the bedding and underwear regularly.
  • Have a bath or shower as soon as you get up in the morning. Do not share towels. 

Is there anything else I need to know about this medicine?

Mebendazole may harm an unborn baby. If your daughter thinks that she may be pregnant she should tell her doctor before taking Mebendazole.

  • Your child must take the medicine for the number of days that your doctor has told you to, or until all the medicine has been taken. If you stop giving the medicine too soon the worm infection may come back.
  • Your doctor will probably recommend that all members of the family are treated on the same day, whether or not they have any symptoms of infection (unless they are pregnant).
  • Mebendazole should not be given to children under 2 years of age. 

General advice about medicines

  • Try to give medicines at about the same times each day, to help you remember.
  • If you are not sure a medicine is working, contact your doctor but continue to give the medicine as usual in the meantime. Do not give extra doses, as you may do harm.
  • Make sure that the medicines you have at home have not reached the ‘best before’ or ‘use by’ date on the packaging. Give old medicines to your pharmacist to dispose of.

If you think someone else may have taken the medicine by accident, contact your doctor straight away.

Where should I keep this medicine?

  • Keep the medicine in a cupboard, away from heat and direct sunlight.
  • It does not need to be kept in the fridge.
  • Make sure that children cannot see or reach the medicine.
  • Keep the medicine in the container it came in.

Who to contact for more information?

Your doctor, pharmacist or nurse will be able to give you more information about Mebendazole and about other medicines used to treat worm infections.

England: NHS 111

Tel 111

Scotland: NHS 24

Northern Ireland: NI Direct

Wales: NHS 111 Wales

Copyright disclaimer

Version [2]. © NPPG, RCPCH and WellChild, all rights reserved. Review by March 2022.

The primary source for the information in this leaflet is the British National Formulary for Children. For details on any other sources used for this leaflet, please contact us through our website,

We take great care to make sure that the information in this leaflet is correct and up-to-date. However, medicines can be used in different ways for different patients. It is important that you ask the advice of your doctor or pharmacist if you are not sure about something. This leaflet is about the use of these medicines in the UK, and may not apply to other countries. The Royal College of Paediatrics and Child Health (RCPCH), the Neonatal and Paediatric Pharmacists Group (NPPG), WellChild and the contributors and editors cannot be held responsible for the accuracy of information, omissions of information, or any actions that may be taken as a consequence of reading this leaflet.