Another commonly used name is Bayer 2502.

• Antiprotozoal, systemic

Nifurtimox (nye-FER-tim-oks) belongs to a group of medicines called antiprotozoals. It is used to treat an infection called American trypanosomiasis (Chagas' disease). Nifurtimox works by killing the protozoa (tiny, one-celled animals) that cause the infection.

Nifurtimox is available only with your doctor's prescription in the following dosage form:

Oral
• Tablets (Argentina and Germany)

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 nifurtimox, the following should be considered:

Allergies—Tell your doctor if you have ever had any unusual or allergic reaction to nifurtimox. Also tell your health care professional if you are allergic to any other substances, such as foods, preservatives, or dyes.

Pregnancy—Studies have not been done in pregnant women. In animal studies, this medicine has not been shown to cause birth defects. However, when used in very large doses, nifurtimox caused a decrease in the weight of the offspring.

Breast-feeding—It is not known whether nifurtimox passes into human breast milk. Although most medicines pass into breast milk in small amounts, many of them may be used safely while breast-feeding. Mothers who are taking this medicine and who wish to breast-feed should discuss this with their doctor.

Children—Although there is no specific information comparing use of nifurtimox in children with use in other age groups, this medicine is not expected to cause different side effects or problems in children than it does in adults.

Older adults—Many medicines have not been studied specifically in older people. Therefore, it may not be known whether they work exactly the same way they do in younger adults or if they cause different side effects or problems in older people. There is no specific information comparing use of nifurtimox in the elderly with use in other age groups.

Other 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 nifurtimox, it is especially important that your health care professional know if you are taking any of the following:

• Alcohol—Taking alcohol with nifurtimox may cause unwanted effects

• Alcohol and/or drug abuse (or history of) or
• Allergies, especially of skin (or history of) or
• Convulsions (seizures) and other brain disease (or history of) or
• Nerve disease, such as numbness, tingling, pain, or weakness in hands or feet (or history of)—Nifurtimox may make these conditions worse

• Kidney disease or
• Liver disease—Higher blood levels of nifurtimox may result, which may increase the chance of side effects

Take this medicine with meals to decrease the chance of stomach upset. If you get an upset stomach and it does not go away after a short time, check with your doctor.

To help clear up your infection, take this medicine exactly as directed by your doctor for the full time of treatment.

When giving nifurtimox to infants, crush the tablets and mix them with some food at the beginning of a meal.

Dosing—

The dose of nifurtimox 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 nifurtimox. If your dose is different, do not change it unless your doctor tells you to do so.

The number of tablets 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 severity of the medical problem for which you are taking nifurtimox .

• For oral dosage form (tablets):
  • For Chagas' disease:
    • Adults and children 17 years of age and over—Dose is based on body weight and must be determined by your doctor. The usual dose is 8 to 10 milligrams (mg) per kilogram (kg) (3.6 to 4.5 mg per pound) of body weight per day divided into three or four smaller doses. Treatment should be given for ninety to one hundred twenty days.
    • Children up to 10 years of age—Dose is based on body weight and must be determined by your doctor. The usual dose is 15 to 20 mg per kg (6.8 to 9.0 mg per pound) of body weight per day divided into three or four smaller doses. Treatment should be given for ninety days. For severe infection, treatment should be given for one hundred twenty days.
    • Children 11 to 16 years of age—Dose is based on body weight and must be determined by your doctor. The usual dose is 12.5 to 15 mg per kg (5.6 to 6.8 mg per pound) of body weight per day divided into three or four smaller doses. Treatment should be given for ninety days. For severe infection, treatment should be given for one hundred twenty days.

Missed dose—

If you miss a dose of this medicine, 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.

Storage—

To store this medicine:

• Keep out of the reach of children.
• Store away from heat and direct light.
• Do not store in the bathroom, near the kitchen sink, or in other damp places. Heat or moisture may cause the medicine to break down.
• Do not keep outdated medicine or medicine no longer needed. Be sure that any discarded medicine is out of the reach of children.

It is important that your doctor check your progress at regular visits. This is to help make sure that the infection is cleared up completely. Also, your weight needs to be checked regularly by your doctor because nifurtimox can cause loss of appetite resulting in loss of weight. The dose of your medicine may have to be adjusted by your doctor based on your weight.

If your symptoms become worse, check with your doctor .

Drinking alcoholic beverages while taking this medicine may cause some unwanted effects. Other alcohol-containing preparations (for example, elixirs, cough syrups, tonics) may also cause problems. Therefore, do not drink alcoholic beverages or take other alcohol-containing preparations while you are taking nifurtimox.

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 as soon as possible if any of the following side effects occur:

• Less common
  • Skin rash 
  
  

• Rare
  • Chills or sore throat;  clumsiness or unsteadiness;  confusion;  convulsions (seizures);  decreased sexual drive or ability;  fever;  forgetfulness ;  irritability;  mood or mental changes;  muscle weakness;  numbness tingling, pain, or weakness in hands or feet;  trembling;  trouble in sleeping;  uncontrolled back-and-forth and/or rolling eye movements;  unusual excitement, nervousness, or restlessness 
  
  

Other 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. However, check with your doctor if any of the following side effects continue or are bothersome:

• More common
  • Abdominal or stomach pain;  dizziness ;  headache;  loss of appetite ;  nausea;  vomiting;  weight loss 
  
  

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