In the U.S.—

• Antibacterial, antileprosy agent
• Antibacterial, antimycobacterial

Ethionamide (e-thye-ON-am-ide) is used with other medicines to treat tuberculosis (TB). Ethionamide may also be used for other problems as determined by your doctor.

To help clear up your tuberculosis (TB) completely, you must keep taking this medicine for the full time of treatment, even if you begin to feel better. This is very important. It is also important that you do not miss any doses.

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

Oral
• Tablets (U.S.)

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 ethionamide, the following should be considered:

Allergies—Tell your doctor if you have ever had any unusual or allergic reaction to ethionamide, isoniazid (e.g., INH; Nydrazid), pyrazinamide, or niacin (e.g., Nicobid; nicotinic acid). Also tell your health care professional if you are allergic to any other substances, such as foods, preservatives, or dyes.

Pregnancy—Ethionamide causes birth defects in rats and rabbits given doses greater than the usual human dose. However, women with tuberculosis (TB) should be treated with medicines to treat TB. If you have any concerns, talk to your doctor.

Breast-feeding—It is not known whether ethionamide passes into 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 ethionamide 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 ethionamide 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 ethionamide, it is especially important that your health care professional know if you are taking any of the following:

• Cycloserine—Use of ethionamide with cycloserine may increase the chance for nervous system side effects, such as convulsions (seizures)

• Diabetes mellitus (sugar diabetes)—Diabetes may be harder to control in patients taking ethionamide

• Liver disease (severe)—Patients with severe liver disease may have an increased chance of side effects

Ethionamide may be taken with or after meals if it upsets your stomach.

To help clear up your tuberculosis (TB) completely, it is very important that you keep taking this medicine for the full time of treatment, even if you begin to feel better after a few weeks. You may have to take it every day for 1 to 2 years or more. It is important that you do not miss any doses.

Your doctor may also want you to take pyridoxine (e.g., Hexa-Betalin; vitamin B ₆) every day to help prevent or lessen some of the side effects of ethionamide. If so, it is very important to take pyridoxine every day along with this medicine. Do not miss any doses.

Dosing—

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

• For oral dosage form (tablets):
  • For the treatment of tuberculosis (TB):
    • Adults and teenagers—250 milligrams (mg) every eight to twelve hours. Ethionamide must be taken with other medicines to treat tuberculosis.
    • Children—Dose is based on body weight. The usual dose is 4 to 5 mg per kilogram of body weight every eight hours. Ethionamide must be taken with other medicines to treat tuberculosis.

Missed dose—

If you do miss a dose of either of these medicines, 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.

If your symptoms do not improve within 2 to 3 weeks, or if they become worse, check with your doctor.

It is very important that your doctor check your progress at regular visits. Also, check with your doctor immediately if blurred vision or any loss of vision, with or without eye pain, occurs during treatment. Your doctor may want you to have your eyes checked by an ophthalmologist (eye doctor).

Since this medicine may cause blurred vision or loss of vision, make sure you know how you react to this medicine before you drive, use machines, or do anything else that could be dangerous if you are not able to see well.

If this medicine causes clumsiness; unsteadiness; or numbness, tingling, burning, or pain in the hands and feet, check with your doctor immediately. These may be early warning symptoms of more serious nerve problems that could develop later.

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:

• Less common
  • Clumsiness or unsteadiness;  confusion ;  mental depression;  mood or other mental changes;  numbness, tingling, burning, or pain in hands and feet;  yellow eyes or skin 
  
  

• Rare
  • Blurred vision or loss of vision, with or without eye pain;  changes in menstrual periods;  coldness ;  decreased sexual ability (in males);  difficulty in concentrating;  dry, puffy skin;  faster heartbeat;  increased hunger;  nervousness;  shakiness;  skin rash;  swelling of front part of neck;  weight gain 
  
  

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
  • Dizziness (especially when getting up from a lying or sitting position);  loss of appetite;  metallic taste;  nausea or vomiting;  sore mouth 
  
  

• Less common or rare
  • Enlargement of the breasts (in males) 
  
  

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

Once a medicine has been approved for marketing for a certain use, experience may show that it is also useful for other medical problems. Although these uses are not included in product labeling, ethionamide is used in certain patients with the following medical conditions:

• Atypical mycobacterial infections, such as Mycobacterium avium complex (MAC)
• Leprosy (Hansen's disease)

Other than the above information, there is no additional information relating to proper use, precautions, or side effects for these uses.