Benznidazole : Uses, Side Effects, Interactions & More

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

How should this medicine be used?
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 time every day and take your doses about 12 hours apart. Follow the directions on your prescription label carefully and ask your doctor or pharmacist to explain any parts you do not understand. Take benznidazole exactly as directed. Do not take more or less or take it more often than prescribed by your doctor.

Benznidazole 100 mg tablets are scored so they can be easily divided into halves or quarters. If your doctor has told you to take only one part of a tablet, hold the tablet between your thumb and forefinger near the marked line and apply pressure to separate the number of parts needed for the dose. Use only a part of a tablet that has been broken at the marked line.

If you cannot swallow the tablets whole, you can dissolve them in water. Put the prescribed number of tablets (or tablet servings) in a drinking cup. Add the amount of water prescribed by your doctor or pharmacist to the cup. Wait 1 to 2 minutes to allow the tablets to disintegrate in the cup, then gently shake the contents of the cup to mix. Drink the mixture immediately. Then rinse the cup with an additional amount of water as directed by your doctor and drink the entire amount. Drink all of this mixture to make sure you get all of the medicine.

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

What special precautions should I follow?

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 in 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 closely for side effects.
  • Tell your doctor if you have or have ever had a blood disorder or liver disease.
  • Tell your doctor if you are pregnant or plan to become pregnant. Women who can become pregnant should take a pregnancy test before starting this medicine. You must 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 harm an unborn baby.
  • Do not breastfeed while taking benznidazole.
  • You should know that this medicine can 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 you are taking this medicine and for at least 3 days after your treatment ends. Alcohol and propylene glycol can cause nausea, vomiting, stomach cramps, headache, sweating, and flushing (flushing of the face) when taken during treatment with benznidazole.

What special dietary instructions should I follow?
Unless your doctor tells you otherwise, continue your normal diet.

What should I do if I forget a dose?
Take the missed dose as soon as you remember. However, if it is almost time for the next dose, skip the missed dose and continue your regular dosing schedule. Do not take a double dose to make up for the one you forgot.

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 medicine.

If you experience a serious side effect, you or your doctor can submit a report online to the Food and Drug Administration’s (FDA) MedWatch Adverse Event Reporting program ( or by phone (1-800-332-1088).

What should I know about storage and disposal of this medication?
Keep this medicine in the container it came in, tightly closed, and out of the reach of children. Store at room temperature and away from excess heat and moisture (not in the bathroom).

It is important to keep all medicines out of the sight and reach of children, as many containers (such as those containing weekly pills and those for eye drops, creams, patches and inhalers) are not child-resistant and small children can easily open them. To protect young children from poisoning, always close the safety caps and immediately place the medicine in a safe place, one that is upright and out of their sight and reach.

Unnecessary medications must be disposed of in special ways to ensure that pets, children, and others cannot consume them. However, you should not flush this medicine down the toilet. Instead, the best way to dispose of your medications is through a drug take-back program. Talk to your pharmacist or contact your local garbage / recycling department to find out about take-back programs in your community. Check out the FDA drug safe disposal website ( for more information if you do not have access to a take-back program.

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In case of emergency/overdose
In case of overdose, call the poison control helpline at 1-800-222-1222. Information is also available online at If the victim collapsed, had a seizure, is having trouble breathing, or cannot wake up, immediately call 911 for emergency services.

What other information should I know?
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 medicine. Ask your pharmacist any questions you have about refilling your prescription.

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

Disclaimer: DrLinex has made every effort to ensure that all information is factually accurate, comprehensive and up-to-date. However, this article should not be used as a licensed health care professional’s choice of knowledge and expertise. You should always consult your doctor or other health care professional before taking any medication. The information given here is subject to change and it has not been used to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions or adverse effects. The lack of warning or other information for any drug does not indicate that the combination of medicine or medication is safe, effective or appropriate for all patients or all specific uses.

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