Generic name: ethambutol (eth AM bue tol)
Brand name: Myambutol
Dosage forms: oral tablet (100 mg; 400 mg)
Drug class: Miscellaneous antituberculosis agents

Ethambutol is an antibiotic that prevents growth of the tuberculous bacteria in the body.

Ethambutol is used to treat tuberculosis (TB), and is usually given together with at least one other tuberculosis medicine.

Ethambutol may also be used for purposes not listed in this medication guide.


Ethambutol can cause serious vision problems or irreversible vision loss. You may not be able to take ethambutol if you have an eye problem or vision disorder.

Before taking this medicine

You should not use ethambutol if you are allergic to it. You may not be able to take ethambutol if you have an eye condition called optic neuritis (inflammation of nerve fibers behind your eyes). Your doctor will decide if this treatment is right for if you have an eye disorder.

Ethambutol can cause vision problems that may be a sign that you should stop taking the medicine. You may not be able to take ethambutol if you cannot recognize or report any changes in your vision. Young children or debilitated patients may not be able to tell someone about vision problems.

To make sure ethambutol is safe for you, tell your doctor if you have:

  • inflammatory eye disorders such as uveitis or iritis;
  • eye problems caused by diabetes;
  • cataracts;
  • liver disease;
  • kidney disease; or
  • gout.

FDA pregnancy category C. It is not known whether ethambutol will harm an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant while using this medicine.

Ethambutol can pass into breast milk and may harm a nursing baby. Tell your doctor if you are breast-feeding a baby.

Ethambutol should not be given to a child younger than 13 years old.

How should I take ethambutol?

Follow all directions on your prescription label. Your doctor may occasionally change your dose to make sure you get the best results. Do not take ethambutol in larger or smaller amounts or for longer than recommended.

Tell your doctor if you have ever used tuberculosis medicine before. Your dose may be different if you have been treated for tuberculosis in the past.

You may take ethambutol with or without food.

Ethambutol may be taken with food if it upsets your stomach.

Tell your doctor if you have any changes in weight. Ethambutol doses are based on weight and your dose may also need to be changed.

Your vision will need to be checked often while you are taking ethambutol. If you wear glasses, take them with you to your vision examination.

Your blood cells, kidney function, and liver function may also need to be checked.

Use this medicine for the full prescribed length of time. Your symptoms may improve before the infection is completely cleared. Skipping doses may also increase your risk of further infection that is resistant to antibiotics. Ethambutol will not treat a viral infection such as the flu or a common cold.

Tuberculosis is sometimes treated with a combination of drugs. Use all medications as directed by your doctor. Read the medication guide or patient instructions provided with each medication. Do not change your doses or medication schedule without your doctor's advice.

Store at room temperature away from moisture and heat.

What happens if I miss a dose?

Take the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not take extra medicine to make up the missed dose.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

What should I avoid while taking ethambutol?

Avoid taking an antacid containing aluminum hydroxide (Alternagel, Maalox, Mi-Acid, Mylanta, Rulox) within 4 hours after you take ethambutol. Some antacids can make it harder for your body to absorb ethambutol.

Ethambutol side effects

Get emergency medical help if you have any of these signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Ethambutol can cause serious vision problems, including vision loss that may be permanent. Stop using ethambutol and call your doctor at once if you have any problems with one or both of your eyes, such as:

  • blurred vision or trouble focusing;
  • loss of vision in one eye that lasts an hour or longer;
  • increased sensitivity of your eyes to light;
  • loss of color vision; or
  • pain with eye movement, pain behind your eyes.

Call your doctor at once if you have:

  • new or worsening cough with fever, trouble breathing;
  • numbness of tingling in your hands or feet;
  • confusion, hallucinations;
  • fever, swollen glands, painful mouth sores, skin sores, cold or flu symptoms, general ill feeling;
  • easy bruising or bleeding (nosebleeds, bleeding gums);
  • chest pain or shortness of breath with mild exertion;
  • little or no urinating;
  • liver problems--upper stomach pain, dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes); or
  • severe skin reaction--fever, sore throat, swelling in your face or tongue, burning in your eyes, skin pain, followed by a red or purple skin rash that spreads (especially in the face or upper body) and causes blistering and peeling.

Common side effects may include:

  • itching or rash;
  • joint pain;
  • headache, dizziness; or
  • nausea, vomiting, stomach pain, indigestion, loss of appetite.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

What other drugs will affect ethambutol?

Other drugs may interact with ethambutol, including prescription and over-the-counter medicines, vitamins, and herbal products. Tell each of your health care providers about all medicines you use now and any medicine you start or stop using.