Medication Information Leaflet

What is this medication for?

Mebendazole is used to treat worm infections. 

It is used mainly for infections of the gut such as threadworms and other less common worm infections (whipworm, roundworm and hookworm). It works by stopping worms from using sugar (glucose) to live, thus killing the worms.

How should I take/use this medication?

  • Take this medication as instructed by your healthcare professional. The dose depends on the type of worm infection you have. 
  • You may take this medication with or without food.
  • [For Vermox brand] Chew the tablet completely before swallowing. Do not swallow whole.
  • Do not stop taking your medication without checking with your healthcare professional.

What should I do if I forget to take/use this medication?

If you forget to take a dose, take it as soon as you remember. However, if it is close to your next dose, skip the missed dose and continue with the next usual dose. 

Do not take two doses to make up for the missed dose.

What precautions should I take?

Inform your healthcare professional if: 

  • You are also taking a medication called Metronidazole (commonly known as Flagyl), commonly used to treat bacterial, parasitic, or other types of infection. 
  • You are allergic to this medication or any of the other ingredients of this medication.
  • You are pregnant, planning to become pregnant, or breastfeeding (remove if not needed).
  • You are taking any other medications, including supplements, traditional medications and herbal remedies.

It is important to note that Mebendazole kills worms but not their eggs. You may need to take a second dose after 2 weeks.

It is also important to have good personal hygiene for at least 6 weeks to prevent the worms from coming back or infecting other people around you, such as:

  • Keep your nails short
  • Do not bite your nails or suck your fingers
  • Wear pyjamas or underclothes in bed
  • Wash your bottom thoroughly every morning
  • Use a separate towel for each person in the house
  • Change clothes regularly
  • Wash and iron bed linen regularly
  • Wash hands and nails well after using the toilet and before meals

What are some common side-effects of this medication?

  • Diarrhea or vomiting
  • Decreased appetite
  • Bloatedness or pain or discomfort in stomach/abdomen area

This is not a list of all possible side effects. If you have questions about side effects, speak to your healthcare professional during your next appointment. However, if you experience any severe side effects, do see your healthcare professional immediately.

What are some rare but serious side-effects that I need to seek medical advice immediately?

The symptoms of a drug allergy include one or more of the following: 

  • Swollen face/eyes/lips/tongue
  • Difficulty in breathing
  • Itchy skin rashes over your whole body

Other rare but serious side effects:

  • Liver problems: 
    • Dark brown urine, light coloured stools (pale grey/clay coloured)
    • Nausea, vomiting, loss of appetite
    • Yellowing of skin or eyes
  • Low white blood cell counts that may increase your risk of infections:
    • Fever, chills, sore throat
  • Seizures

If you experience any of these symptoms, you should stop your medication and see your healthcare professional immediately.

What food or medication should I avoid when I take this medication?

Inform your healthcare professional if you are taking Metronidazole (a medicine used commonly to treat infections) or any other medications/supplements/herbal remedies.

How should I store this medication?

Store in a cool and dry place, away from direct sunlight. Keep this medication away from children.

How should I throw away this medication safely?

Pack the medication into a bag and bring it back to the pharmacy where you received the medication from.


Please take note that the above is not a complete list of all possible side effects. If you have any concerns about your medication or if you have other side effects that you think are caused by this medication, please consult your doctor or pharmacist.

If you take more than the recommended dose, please seek medical advice immediately. The information provided on this page does not replace information from your healthcare professional. Please consult your healthcare professional for more information.

This article is jointly developed by members of the National Medication Information workgroup. The workgroup consists of cluster partners (National Healthcare Group, National University Health System and SingHealth), community pharmacies (Guardian, Unity and Watsons) and Pharmaceutical Society of Singapore. The content does not reflect drug availability and supply information in pharmacies and healthcare institutions. You are advised to check with the respective institutions for such information.

Last updated in December 2023

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