How does this medication work? What will it do for me?

Mebendazole belongs to the class of medications called anthelminthics. It is used to treat infections of several types of parasitic worms that live in the digestive system. These parasites include pinworms, roundworms, whipworms, and hookworms. Mebendazole has also been used to treat threadworms and large tapeworms. These parasitic infections are most common in the rural and developing regions of tropical and sub-tropical areas around the world.

Mebendazole is believed to work by preventing the worms from absorbing sugars, and by doing so, prevents the parasite from getting the energy needed for survival. Gradually, the worms die off, getting rid of the infection.

This medication may be available under multiple brand names and/or in several different forms. Any specific brand name of this medication may not be available in all of the forms or approved for all of the conditions discussed here. As well, some forms of this medication may not be used for all of the conditions discussed here.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. If you have not discussed this with your doctor or are not sure why you are taking this medication, speak to your doctor. Do not stop taking this medication without consulting your doctor.

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to take this medication if their doctor has not prescribed it.

What form(s) does this medication come in?

Each faintly orange, flat-faced, round tablet inscribed with "JANSSEN" on one side and "Me/100" (scored) on the other side contains 100 mg of mebendazole. Nonmedicinal ingredients: microcrystalline cellulose, sodium starch glycolate, talc, corn starch, saccharin sodium, magnesium stearate, cotton seed oil hydrogenated, orange flavour, colloidal anhydrous silica, sodium lauryl sulphate, and FD&C Yellow No. 6 (orange yellow S).

How should I use this medication?

The dose of mebendazole depends on the type of worm you are treating.

To treat pinworms, adults and children greater than 2 years old should take 1 tablet on the first day, then 1 tablet 2 weeks later and a third tablet 4 weeks after the first tablet. The first dose will get rid of the worms, but not the eggs that the worm may have left behind. The second dose will get rid of the second batch of worms that may have hatched from the eggs. The final dose ensures that all the worms are gone.

To treat other types of infestations, 100 mg (1 tablet) of mebendazole should be taken twice a day for 3 days. If symptoms remain after 3 weeks, your doctor may suggest a second treatment.

Many things can affect the dose of medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are taking the medication without consulting your doctor.

Mebendazole may be taken with food or on an empty stomach. Tablets may be crushed or chewed if necessary to make it easier to take the medication.

It is important to take this medication exactly as prescribed by your doctor.

If you miss a dose, take it as soon as possible and continue with your regular schedule. If it is almost time for your next dose, skip the missed dose and continue with your regular dosing schedule. Do not take a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.

Store this medication at room temperature, protect it from light and moisture, and keep it out of the reach of children.

Do not dispose of medications in wastewater (e.g. down the sink or in the toilet) or in household garbage. Ask your pharmacist how to dispose of medications that are no longer needed or have expired.

Who should NOT take this medication?

Do not take this medication if you are allergic to mebendazole or any ingredients of the medication.

Do not give this medication to infants under 1 year of age.

What side effects are possible with this medication?

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent.

The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

  • diarrhea
  • dizziness
  • hives
  • intestinal gas
  • skin rash
  • stomach ache

Although most of the side effects listed below don't happen very often, they could lead to serious problems if you do not seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

  • hair loss
  • signs of kidney problems (e.g., increased urination at night, decreased urine production, blood in the urine)
  • signs of  liver problems (e.g., nausea, vomiting, diarrhea, loss of appetite, weight loss, yellowing of the skin or whites of the eyes, dark urine, pale stools)

Stop taking the medication and seek immediate medical attention if any of the following occur:

  • seizures
  • signs of a serious allergic reaction (e.g., abdominal cramps, difficulty breathing, nausea and vomiting, or swelling of the face and throat)
  • signs of a severe skin reaction such as blistering, peeling, a rash covering a large area of the body, a rash that spreads quickly, or a rash combined with fever or discomfort

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.

Are there any other precautions or warnings for this medication?

Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.

Pregnancy: The safety and effectiveness of using this medication during pregnancy is not known. Mebendazole should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while taking this medication, contact your doctor immediately.

Breast-feeding: It is not known if mebendazole passes into breast milk. If you are a breast-feeding mother and are taking this medication, it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.

Children: The safety and effectiveness of using this medication have not been established for children less than 2 years old. Mebendazole may be considered for children 1 to 2 years old if the benefits outweigh the potential risks to the child.

What other drugs could interact with this medication?

There may be an interaction between mebendazole and any of the following:

  • antimalarials (e.g., chloroquine, hydroxychloroquine, primaquine)
  • carbamazepine
  • cimetidine
  • metronidazole
  • phenytoin

If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

  • stop taking one of the medications,
  • change one of the medications to another,
  • change how you are taking one or both of the medications, or
  • leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.