How does mebendazole work?
Mebendazole kills worms that cause gut infections such as threadworm (sometimes known as pinworm) and other less common worm infections (whipworm, roundworm and hookworm).
It works by stopping the worms using sugar (glucose). Without glucose, the cells of the worms lose their energy supply and quickly die.
Mebendazole does not kill the eggs of the worm. This is why you may need to take another dose 2 weeks later to help prevent reinfection.
How long does it take to work?
The medicine should start to work straight away but it may take several days to kill all the worms.
It's important to take the medicine as a pharmacist or doctor tells you. Do not stop early if you have been told to take it for several days.
Mebendazole does not kill the worms' eggs, and these can cause you to get worms again and pass it on to other people.
A doctor or pharmacist may advise you to take mebendazole again after 2 weeks, to stop the worms from coming back.
Is it safe to take repeat doses if worms keep coming back?
Mebendazole does not kill the worms' eggs, and these can cause reinfection and also infect other people.
A doctor or pharmacist may advise you to take mebendazole again after 2 weeks, to stop reinfection. However, if the infection comes back, speak to a doctor for advice.
It's also important to have good personal hygiene to stop the worms coming back.
A doctor or pharmacist may also advise that everyone in your house is treated with mebendazole.
Will it affect my contraception?
Mebendazole does not stop any type of contraception from working, including the combined pill, progestogen-only pill or emergency contraception.
But if mebendazole gives you severe diarrhoea for more than 24 hours, your contraceptive pills may not protect you from pregnancy.
If this happens, follow the instructions in the leaflet that comes with your contraceptive pills.
Find out more:
Can I drive or ride a bike?
Yes. Mebendazole should not affect you being able to drive or cycle.
Can I drink alcohol while taking mebendazole?
Yes, you can drink alcohol while taking mebendazole.
Is there any food or drink I need to avoid?
You can eat and drink normally while taking mebendazole.
It's important to remember to wash your hands and scrub under your fingernails before eating. This removes any eggs and stops the infection spreading or coming back.
Are there any lifestyle changes that can help with threadworms?
It's important to have good personal hygiene to stop threadworms from coming back, especially in babies and children under 2 years of age.
It's important to:
- wash your hands and scrub under your fingernails – particularly before eating, after using the toilet or after changing nappies
- encourage children to wash their hands regularly
- bathe or shower every morning
- rinse toothbrushes before using them
- keep fingernails short
- wash sleepwear, sheets and towels regularly
- disinfect kitchen and bathroom surfaces
- vacuum regularly and dust using a damp cloth
- make sure children wear underwear at night and change them in the morning