Ethambutol belongs to the family of medications known as antimycobacterial antibiotics. It is used in combination with at least one other tuberculosis medication to treat tuberculosis infections caused by mycobacterium (a type of bacteria that causes tuberculosis). It is believed to work by preventing the bacteria from continuing to grow.

This medication may be available under multiple brand names and/or in several different forms. Any specific brand name of this medication may not be available in all of the forms or approved for all of the conditions discussed here. As well, some forms of this medication may not be used for all of the conditions discussed here.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. If you have not discussed this with your doctor or are not sure why you are taking this medication, speak to your doctor. Do not stop taking this medication without consulting your doctor.

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to take this medication if their doctor has not prescribed it.

The dose of ethambutol depends on body weight and will be determined by your doctor.

For adults and children 13 years of age and over who have not used ethambutol before, the recommended dose is 15 mg per kilogram of body weight once daily (to a maximum of 2.5 g).

For adults and children aged 13 years and older who have used ethambutol before, the recommended dose is 25 mg per kilogram of body weight once daily. After 60 days of treatment, or when the infection clears up, the dose can be decreased to 15 mg per kilogram of body weight once daily.

When ethambutol is used in combination with other tuberculosis medications, a dose of 50 mg per kilogram of body weight (to a maximum of 2.5 g) can be taken twice a week. Alternatively, ethambutol can be used at a dose of 25 mg per kilogram of body weight to 30 mg per kilogram of body weight (to a maximum of 2.5 g) 3 times a week.

Children's dosage: Dosage has not been established for children less than 13 years of age but your doctor may consider ethambutol for children under 13 years, especially if other tuberculosis medications have not worked. It is not recommended for children whose visual changes cannot be monitored (e.g., children younger than 6 years of age).

Many things can affect the dose of a medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are taking the medication without consulting your doctor.

Ethambutol must be taken for the recommended duration of treatment, even if you are feeling better. This will reduce the chances of having remaining bacteria grow back.

Ethambutol can be taken with or without food. It should be taken as a single daily dose, at the same time each day, and preferably in the morning.

Ethambutol should never be used on its own and should always be used in combination with other tuberculosis medications.

It is important to take this medication exactly as prescribed by your doctor. If you miss a dose, take it as soon as possible and continue with your regular schedule. If it is almost time for your next dose, skip the missed dose and continue with your regular dosing schedule. Do not take a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.

Store this medication at room temperature; protect it from light, moisture, and excessive heat; and keep it out of the reach of children.

100 mg
Each blue, round, film-coated tablet, single-scored on one side, contains ethambutol HCl, USP 100 mg. Nonmedicinal ingredients: cornstarch, hydroxypropyl cellulose, lactose, magnesium stearate, polyvinyl alcohol, polyethylene glycol, titanium dioxide, talc, FD&C Blue No. 1 Aluminum Lake, and D&C Yellow No. 10 Aluminum Lake.

400 mg
Each blue, round, film-coated tablet, single-scored on one side and embossed "ICN E12" on the other, contains ethambutol HCl, USP 400 mg. Nonmedicinal ingredients: alcohol, cornstarch, hydroxypropyl cellulose, lactose, magnesium stearate polyvinyl alcohol, polyethylene glycol, titanium dioxide, talc, FD&C Blue No. 1 Aluminum Lake, and D&C Yellow No. 10 Aluminum Lake.

Do not take ethambutol if you:

• are allergic to ethambutol or to any of the ingredients of the medication
• have or have had inflammation of the optic nerve

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent. The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

• dizziness
• headache
• loss of appetite
• nausea
• stomach pain or discomfort
• vomiting

Although most of these side effects listed below don't happen very often, they could lead to serious problems if you do not check with your doctor or seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

• disorientation or confusion
• fever
• hallucinations
• joint pain
• numbness or tingling in the legs or arms
• signs of liver problems (e.g., nausea, vomiting, diarrhea, loss of appetite, weight loss, yellowing of the skin or whites of the eyes, dark urine, pale stools)
• skin rash and itching
• vision problems in either eye (e.g., decreased vision, loss of red-green colour vision)

Stop taking the medication and seek immediate medical attention if any of the following occur:

• signs of an allergic reaction (e.g., shortness of breath or difficulty breathing; hives; swelling of the eyes, mouth, lips, or throat)

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.

Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.

Eye problems: Ethambutol may cause eye problems associated with inflammation of the optic nerve such as decreased vision and loss of red-green colour vision. Normal vision is usually restored within weeks or months of stopping the medication. Your doctor will recommend monthly eye examinations, especially if you are receiving a daily dose greater than 15 mg per kilogram of body weight, have kidney problems, or have other eye problems (e.g., cataracts).

Gout: Some people taking ethambutol have experienced an increase of uric acid in the blood, causing gout. Symptoms of an acute gout attack include sudden pain, swelling, and stiffness in the affected joint, often the big toe. You may also experience a fever. If this is your first attack, seek medical attention as soon as possible. If you have had gout attacks before, follow your doctor's instructions for dealing with the attack.

Kidney disorders: People with kidney disease or reduced kidney function should discuss with their doctor how this medication may affect their medical condition, how their medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Liver disorders: People with liver disease or reduced liver function should discuss with their doctor how this medication may affect their medical condition, how their medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Pregnancy: Ethambutol is considered to be safe for use by pregnant people.

Breast-feeding: Ethambutol passes into breast milk, but it is considered to be safe for use by those who are breast-feeding.

Children: The safety and effectiveness of using this medication have not been established for children under 13 years of age. Dosage has not been established for children under 13 years of age but your doctor may consider ethambutol for children under 13 years, especially if other tuberculosis medications have not worked. Because ethambutol can cause vision problems, it is not recommended for children whose visual changes cannot be monitored (e.g., children younger than 6 years of age).

For a full list of interactions, use the Drug Interaction Checker available on the Drugs.com website.

If you are taking other medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

• stop taking one of the medications,
• change one of the medications to another,
• change how you are taking one or both of the medications, or
• leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.