Other drug names:	A-Am  An-Az  B  C-Ch  Ci-Cz  D-Dh  Di-Dz  E  F  G  H  I-J  K-L  M-Mh  Mi-Mz  N-Nh  Ni-Nz  O  P-Pl  Pm-Pz  Q-R  S-Sn  So-Sz  T-To  Tp-Tz  U-V  W-Z  0-9

• Antibacterial, antimycobacterial

Ethambutol (e-THAM-byoo-tole) and isoniazid ( eye-soe-NYE-a-zid) is a combination anti-infective medicine. This combination medicine is used to treat tuberculosis (TB). It may be given in combination with other medicines to treat TB.

This medicine may cause some serious side effects, including damage to the liver. Liver damage is more likely to occur in patients older than 50 years of age. You and your doctor should talk about the good this medicine will do, as well as the risks of taking it.

To help clear up your TB infection 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.

Ethambutol and isoniazid combination is available only with your doctor's prescription, in the following dosage form:

Oral
• Tablets (Africa, Asia, and Latin America)

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 ethambutol and isoniazid combination, the following should be considered:

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

Pregnancy—Pregnant women with tuberculosis (TB) should be treated with TB medicines, including ethambutol and isoniazid. Ethambutol and isoniazid have not been shown to cause birth defects or other problems in humans. However, studies in animals have shown that ethambutol causes cleft palate, skull and spine defects, absence of one eye, and harelip.

Breast-feeding—Both ethambutol and isoniazid pass into the breast milk. However, ethambutol and isoniazid have not been reported to cause problems in nursing babies.

Children—Ethambutol or combination medications containing ethambutol may be used for children with TB when other medicines cannot be used. However, ethambutol or combination medications containing ethambutol usually are not used in children younger than 6 years of age because it may be hard to tell if they are having side effects affecting their eyes.

Older adults—Hepatitis may be especially likely to occur in patients older than 50 years of age, who are usually more sensitive than younger adults to the effects of isoniazid.

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 ethambutol and isoniazid combination, it is especially important that your health care professional know if you are taking any of the following:

• Alcohol or
• Carbamazepine (e.g., Tegretol) or
• Disulfiram (e.g., Antabuse) or
• Ketoconazole (e.g., Nizoral) or
• Phenytoin (e.g., Dilantin) or
• Rifampin (e.g., Rifadin)—These medicines may increase the chance of side effects if taken with ethambutol and isoniazid combination

Other medical problems—The presence of other medical problems may affect the use of this medicine. Make sure you tell your doctor if you have any other medical problems, especially:

• Alcohol abuse (or history of) or
• Liver disease—There may be an increased chance of hepatitis with daily drinking of alcohol or in patients with liver disease

• Gouty arthritis—Ethambutol and isoniazid combination may cause or worsen attacks of gout

• Kidney disease (severe)—There may be an increased chance of side effects in patients with severe kidney disease

• Optic neuritis (eye nerve damage)—Ethambutol and isoniazid combination may cause or worsen eye disease

• Seizure disorders such as epilepsy—There may be an increased chance of convulsions (seizures) in some patients

If ethambutol and isoniazid combination upsets your stomach, take it with food. Antacids may also help. However, do not take aluminum-containing antacids within 1 hour of taking this medicine. They may keep this medicine from working properly.

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 as long as 6 months to 2 years. It is important that you do not miss any doses.

Your doctor may also want you to take pyridoxine (vitamin B ₆) every day to help prevent or lessen some of the side effects of isoniazid. This usually is not needed in children, who receive enough pyridoxine in their diet. If it is needed, it is very important to take pyridoxine every day along with this medicine. Do not miss any doses .

Dosing—

The dose of ethambutol and isoniazid combination 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 ethambutol and isoniazid combination. If your dose is different, do not change it unless your doctor tells you to do so.

• For oral dosage form (tablets):
  • For treatment of tuberculosis:
    • Adults and teenagers—800 mg ethambutol and 300 mg isoniazid once a day.
    • Children up to 13 years of age—Dose must be determined by your doctor.

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 the tablet form of this medicine 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 very important that your doctor check your progress at regular visits. Also, check with your doctor immediately if blurred vision, red-green color blindness, or 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).

Also, 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 alert or able to see well.

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

Certain foods such as cheese (Swiss or Cheshire) or fish (tuna, skipjack, or Sardinella) may rarely cause reactions in some patients taking this medicine. Check with your doctor if redness or itching of the skin, hot feeling, fast or pounding heartbeat, sweating, chills or clammy feeling, headache, or light-headedness occurs while you are taking this medicine.

Liver problems may be more likely to occur if you drink alcoholic beverages regularly while you are taking this medicine. Also, the regular use of alcohol may keep this medicine from working properly. Therefore, you should strictly limit the amount of alcoholic beverages you drink while you are taking this medicine.

If this medicine causes you to feel very tired or very weak, or causes clumsiness, unsteadiness, a loss of appetite, nausea, numbness, tingling, burning, or pain in the hands and feet, or vomiting, check with your doctor immediately. These may be early warning signs of more serious liver or nerve problems that could develop later.

For diabetic patients:
• This medicine may cause false test results with some urine sugar tests. Check with your doctor before changing your diet or the dosage of your diabetes medicine.

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
  • Clumsiness or unsteadiness;  dark urine ;  loss of appetite;  nausea ;  numbness, tingling, burning, or pain in hands and feet;  unusual tiredness or weakness;  vomiting;  yellow eyes or skin 
  
  

• Less common
  • Chills;  pain and swelling of joints, especially big toe, ankle, or knee;  tense, hot skin over affected joints 
  
  

• Rare
  • Blurred vision or loss of vision, with or without eye pain;  convulsions (seizures);  fever;  joint pain;  mental depression;  mood or other mental changes;  skin rash ;  sore throat;  unusual bleeding or bruising 
  
  

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
  • Confusion;  diarrhea;  disorientation;  headache;  stomach pain 
  
  

Developed: 02/02/1999