Benznidazole is used to treat Chagas disease (caused by a parasite) in children 2 to 12 years old. Benznidazole is in a class of medications called antiprotozoals. It works by killing the organism that can cause Chagas disease.

Side Effects Of Benznidazole

Benznidazole may cause side effects. Tell your doctor if any of these symptoms are severe or do not go away:

  • headache
  • dizziness
  • stomach pain
  • nausea
  • vomiting
  • diarrhea
  • loss of appetite
  • weight loss
  • uncontrollable shaking of a part of the body

Some side effects can be serious. If you experience any of these symptoms, stop this medication and call your doctor immediately:

  • rash
  • swollen, red, peeling, or blistering skin
  • hives
  • itching
  • red- or purple-colored skin spots
  • fever
  • swollen lymph nodes
  • numbness, pain, burning or tingling in your hands or feet

Benznidazole may cause other side effects. Call your doctor if you have any unusual problems while taking this medication.

Warnings & Precautions

Before taking benznidazole:

  • tell your doctor and pharmacist if you are allergic to benznidazole, metronidazole (Flagyl, in Pylera), any other medications, or any of the ingredients in benznidazole tablets. Ask your pharmacist for a list of the ingredients.
  • tell your doctor if you are taking or have taken disulfiram (Antabuse). Your doctor may tell you not to take benznidazole if you are taking disulfiram or have taken it within the past two weeks.
  • tell your doctor and pharmacist what other prescription and nonprescription medications, vitamins, nutritional supplements, and herbal products you are taking or plan to take. Your doctor may need to change the doses of your medications or monitor you carefully for side effects.
  • tell your doctor if you have or have ever had any blood disorders or liver disease.
  • tell your doctor if you are pregnant or plan to become pregnant. Females who can become pregnant must take a pregnancy test before starting this medication. You should use birth control to prevent pregnancy during your treatment and for 5 days after your final dose. If you become pregnant while taking benznidazole, call your doctor. Benznidazole can cause fetal harm.
  • do not breastfeed while taking benznidazole.
  • you should know that this medication may decrease fertility in men. Talk to your doctor about the risks of taking benznidazole.
  • do not drink alcoholic beverages or take products with alcohol or propylene glycol while taking this medication and for at least 3 days after your treatment is finished. Alcohol and propylene glycol may cause nausea, vomiting, stomach cramps, headache, sweating, and flushing (redness of the face) when taken during treatment with benznidazole.

Benznidazole Dosage

Benznidazole comes as a tablet to take by mouth. It is usually taken with or without food twice a day for 60 days. Take benznidazole at around the same times every day and space your doses about 12 hours apart. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Take benznidazole exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor.

The benznidazole 100-mg tablets are scored so that they can easily be split into halves or quarters. If your doctor has told you to take only part of a tablet, hold the tablet between your thumb and index fingers close to the scored line and apply pressure to separate the number of parts needed for the dose. Only use a portion of a tablet that has been broken at the scored line.

If you are unable to swallow the tablets whole, you may dissolve them in water. Place the prescribed number of tablets (or portions of tablets) into a drinking cup. Add the amount of water as told by your doctor or pharmacist into the cup. Wait for 1 to 2 minutes to allow the tablets to disintegrate in the cup, then gently shake the cup contents to mix. Drink the mixture immediately. Then rinse the cup with an additional amount of water as told by your doctor and drink the entire amount. Drink all of this mixture to be sure that you receive all of the medication.

Ask your pharmacist or doctor for a copy of the manufacturer’s information for the patient.


Keep all appointments with your doctor and the laboratory. Your doctor may order certain lab tests to check your body’s response to benznidazole.

Do not let anyone else take your medication. Ask your pharmacist any questions you have about refilling your prescription.

It is important for you to keep a written list of all of the prescription and nonprescription (over-the-counter) medicines you are taking, as well as any products such as vitamins, minerals, or other dietary supplements. You should bring this list with you each time you visit a doctor or if you are admitted to a hospital. It is also important information to carry with you in case of emergencies.


All information has been provided courtesy of MedLinePlus from the National Library of Medicine and from the FDA.