Skip to main content

Benznidazole (Oral)

Medically reviewed by Last updated on Oct 25, 2021.

Available Dosage Forms:

  • Tablet

Therapeutic Class: Antiprotozoal

Chemical Class: Nitroimidazole

Uses for benznidazole

Benznidazole is used to treat Chagas disease (American trypanosomiasis) in children 2 to 12 years of age.

Chagas disease is a potentially life-threatening disease caused by the protozoan parasite, Trypanosoma cruzi, also known as "kissing bug". It can be transmitted by eating food contaminated with the parasite's feces or urine, blood transfusion from infected donors, organ transplant using organs from infected donors, or during pregnancy or childbirth.

Benznidazole is available only with your doctor's prescription.

Before using benznidazole

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For benznidazole, the following should be considered:


Tell your doctor if you have ever had any unusual or allergic reaction to benznidazole or any other medicines. Also tell your health care professional if you have any other types of allergies, such as to foods, dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully.


Appropriate studies performed to date have not demonstrated pediatric-specific problems that would limit the usefulness of benznidazole in children 2 to 12 years of age. Safety and efficacy have not been established in children younger than 2 years of age and older than 12 years of age.


No information is available on the relationship of age to the effects of benznidazole in geriatric patients.


There are no adequate studies in women for determining infant risk when using this medication during breastfeeding. Weigh the potential benefits against the potential risks before taking this medication while breastfeeding.

Interactions with medicines

Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking benznidazole, it is especially important that your healthcare professional know if you are taking any of the medicines listed below. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.

Using benznidazole with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

  • Capecitabine
  • Cholera Vaccine, Live
  • Doxifluridine
  • Fluorouracil
  • Tegafur

Interactions with food/tobacco/alcohol

Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur. Discuss with your healthcare professional the use of your medicine with food, alcohol, or tobacco.

Proper use of benznidazole

Take benznidazole only as directed by your doctor. Do not take more of it, do not take it more often, and do not take it for a longer time than your doctor ordered.

Benznidazole comes with patient instructions. Read and follow these instructions carefully before you start taking benznidazole and each time you get a refill. Ask your doctor if you have any questions.

This tablet is scored. You may take it whole or broken at the scored lines. You may cut it in half or into fourths as directed by your doctor. Benznidazole may also be given as a slurry.

You may take benznidazole with or without food.


The dose of benznidazole will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of benznidazole. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

  • For oral dosage form (tablets):
    • For the treatment of Chagas disease:
      • Children 2 to 12 years of age—Dose is based on body weight and is usually 5 to 8 milligram (mg) per kilogram (kg) given two times a day, 12 hours apart for 60 days.
        • Children weighing 60 kg or more—200 mg (two 100 mg tablet) given two times a day, 12 hours apart for 60 days.
        • Children weighing 40 kg to less than 60 kg—150 mg (1 ½ 100 mg tablet) given two times a day, 12 hours apart for 60 days.
        • Children weighing 30 kg to less than 40 kg—100 mg (one 100 mg tablet) given two times a day, 12 hours apart for 60 days.
        • Children weighing 20 kg to less than 30 kg—75 mg (six 12.5 mg tablets or ¾ 100 mg tablet) given two times a day, 12 hours apart for 60 days.
        • Children weighing 15 kg to less than 20 kg—62.5 mg (five 12.5 mg tablets) given two times a day, 12 hours apart for 60 days.
        • Children weighing less than 15 kg—50 mg (four 12.5 mg tablets or ½ 100 mg tablet) given two times a day, 12 hours apart for 60 days.
      • Children younger than 2 years of age or older than 12 years of age—Use and dose must be determined by your doctor.

Missed dose

If you miss a dose of benznidazole, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not double doses.


Keep out of the reach of children.

Do not keep outdated medicine or medicine no longer needed.

Ask your healthcare professional how you should dispose of any medicine you do not use.

Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. Keep from freezing.

Keep it in its original bottle.

Precautions while using benznidazole

It is very important that your doctor check your progress at regular visits to make sure benznidazole is working properly. Blood tests may be needed to check for unwanted effects.

Do not use benznidazole if you have taken disulfiram (Antabuse®) within the last two weeks. Also, do not take alcohol or alcoholic products (eg, propylene glycol) during treatment with benznidazole and for at least 3 days after your last dose.

Using benznidazole while you are pregnant can harm your unborn baby. Use an effective form of birth control to keep from getting pregnant during treatment with benznidazole and for 5 days after the last dose. If you think you have become pregnant while using benznidazole, tell your doctor right away.

If you plan to have children, talk with your doctor before using benznidazole. Some men using benznidazole have become infertile (unable to have children).

There is a possible risk of getting cancer with benznidazole. Talk with your doctor if you have any concerns about this risk.

Serious skin reactions can occur with benznidazole. Check with your doctor right away if you have blistering, peeling, or loosening of the skin, red skin lesions, severe acne or a skin rash, sores or ulcers on the skin, or fever or chills with benznidazole.

Check with your doctor right away if you have dizziness, headache, burning, numbness, tingling, or painful sensations, weakness in the arms, hands, legs, or feet, or unsteadiness or awkwardness. These may be signs of peripheral neuropathy.

Benznidazole may lower the number of some types of blood cells in your body. Because of this, you may bleed or get infections more easily. To help with these problems, avoid being near people who are sick or have infections. Wash your hands often. Stay away from rough sports or other situations where you could be bruised, cut, or injured. Brush and floss your teeth gently. Be careful when using sharp objects, including razors and fingernail clippers.

Benznidazole side effects

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur:

More common

  • Black, tarry stools
  • chest pain
  • chills
  • cough
  • fever
  • painful or difficult urination
  • rash
  • sore throat
  • sores, ulcers, or white spots on the lips or in the mouth
  • swollen glands
  • unusual bleeding or bruising
  • unusual tiredness or weakness

Less common

  • Burning, numbness, tingling, or painful sensations
  • headache
  • tremors
  • unsteadiness or awkwardness
  • weakness in the arms, hands, legs, or feet

Incidence not known

  • Bleeding gums
  • blistering, peeling, or loosening of the skin
  • blood in the urine or stools
  • dark urine
  • diarrhea
  • difficulty in moving
  • general tiredness and weakness
  • inability to concentrate
  • itching
  • light-colored stools
  • muscle pain or stiffness
  • nausea
  • pain, swelling, or redness in the joints
  • pinpoint red spots on the skin
  • red, irritated eyes
  • seizures
  • swelling of the eyelid, arms, or legs
  • swollen, painful, or tender lymph glands in the neck, armpit, or groin
  • temporary disorientation
  • temporary loss of memory
  • trouble sleeping
  • upper right abdominal pain
  • vomiting
  • yellow eyes and skin

Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common

  • Decreased appetite
  • decreased weight
  • stomach pain

Incidence not known

  • Bone pain
  • dry mouth
  • loss of sense of taste
  • loss of strength
  • muscle aching or cramping

Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.

Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.