Ethambutol and Isoniazid (Systemic)

Before Using This Medicine

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