What mebendazole is for

Mebendazole is used to treat some types of worm infection, such as:

threadworms (pinworms)
roundworms
whipworms
hookworms

You can buy it from pharmacies to treat threadworms in adults and children aged 2 years or older.

It's only available with a prescription for other worm infections and for children aged from 6 months to 2 years.

Find out about worms in humans.

How to take mebendazole

Mebendazole comes as chewable tablets or a liquid you swallow.

How much you need to take and for how long depends on what type of worm infection you have and whether your symptoms come back.

For threadworm infections, you take a one-off dose. If your symptoms come back, you may need to take another dose 2 weeks later.

For hookworm, whipworm or roundworm infections, you need to take it twice a day, ideally 10 to 12 hours apart, for 3 days.

Always check the packet or leaflet that comes with your medicine. Ask a pharmacist or doctor for advice if you're not sure how to take it or have any problems taking it.

When taking mebendazole:

chew, crush or swallow the tablet whole with a drink of water (always crush the tablet for children)
for liquid mebendazole, shake the bottle well and use the spoon or cup that comes with it to make sure you measure the correct dose

Speak to a doctor if your symptoms have not started to improve after a few days of using mebendazole.

Important

To help stop worms spreading and reduce the risk of getting them again:

everyone aged 2 years or older in your household needs treatment at the same time (speak to a doctor if anyone in the household is pregnant, breastfeeding or younger than 2 years)
wash your hands regularly during the weeks after treatment – particularly after going to the toilet, or before eating or preparing food

If you miss a dose of mebendazole

If you've been prescribed a course of mebendazole and forget to take a dose, take it as soon as you remember, unless it's nearly time for your next dose.

If it's nearly time for your next dose, skip the dose you missed and take your next dose at the usual time.

Do not take 2 doses to make up for a missed dose.

If you take too much mebendazole

Taking an extra dose of mebendazole is unlikely to cause problems, but it's important to get medical advice if you take too much as it can sometimes be dangerous.

Urgent advice: Speak to a pharmacist as soon as possible if:

you've taken more mebendazole than it says on the packet, leaflet or prescription

If you're unable to speak to a pharmacist or you took too much of your medicine on purpose, call NHS 111 for advice.

Call NHS 111 if a child under 2 has taken more than their prescribed dose of mebendazole.

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If you're told to go to A&E, do not drive. Ask someone to drive you or call 999 and ask for an ambulance.

Bring the mebendazole packet or leaflet inside it, any remaining medicine, and any other medicines you take.

Side effects of mebendazole

Like all medicines, mebendazole can cause side effects, although not everyone gets them.

Side effects of mebendazole include:

stomach pain or discomfort
farting
diarrhoea

Mebendazole should not affect your ability to drive, ride a bike or use machinery.

Non-urgent advice: Speak to a pharmacist or doctor if:

you have any side effects that bother you or do not go away

They may be able to give you advice about how you can reduce the side effects. Keep taking your medicine unless you're advised to stop.

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Serious side effects

Mebendazole can sometimes cause serious side effects, although most of them are rare.

Possible serious side effects of mebendazole include:

seizures (fits)
changes in your blood cells – causing symptoms such as tiredness, or getting ill a lot
liver problems – causing symptoms such as itchy skin, darker pee than normal, pale poo and yellowing of the skin or eyes (this may be harder to see on black or brown skin)
an allergic reaction (anaphylaxis) – causing symptoms such as a swollen throat or tongue, a raised, itchy rash and difficulty breathing

Immediate action required: Call 999 if:

you're taking mebendazole and think you're having anaphylaxis or seizures (fits)

If you think you're having any other serious side effect, call NHS 111.

More about side effects

These are not all the side effects of mebendazole.

For a full list, see the leaflet that came with your medicine or search for your medicine leaflet on the electronic medicines compendium website.

You can report any side effects you get on the Yellow Card website

Who can and cannot take mebendazole

Most adults and children aged 2 years or over can take mebendazole. Children aged 6 months to 2 years may be able to take it if prescribed by a doctor.

Mebendazole is not suitable for some people. For example, it may not be suitable if:

you've had an allergic reaction or serious side effect from mebendazole or a similar medicine, such as albendazole or ivermectin

Check the packet or leaflet that comes with your medicine to see if it's suitable for you. Speak to a pharmacist or doctor if you're not sure if you can take or use it.

Breastfeeding and mebendazole

Speak to a pharmacist or doctor if you're breastfeeding.

Mebendazole can often be used while breastfeeding, but it's best to check because the medicine can pass into your breast milk in small amounts.

If you're taking mebendazole while breastfeeding, speak to a healthcare professional if you have any concerns about your baby.

Pregnancy and mebendazole

Speak to a doctor or pharmacist before taking mebendazole if you're pregnant or think you might be pregnant.

Mebendazole can be used in pregnancy if the benefits outweigh the risks to your baby. A doctor may suggest trying hygiene measures, such as washing hands regularly and keeping fingernails short, to treat the infection first, particularly in early pregnancy.

Find out more about taking mebendazole during pregnancy on the Bumps (Best Use of Medicines in Pregnancy) website

Taking mebendazole with other medicines, food and drink

There are some medicines, remedies and supplements that may not mix well with mebendazole.

This includes:

metronidazole, a type of antibiotic
cimetidine, a medicine used lower the amount of stomach acid

Check the packet or leaflet that comes with your medicine to see if it's suitable for you. Speak to a pharmacist or doctor if you're not sure you can take it.

Mebendazole (Ovex) - Other common brands: Vermox