Along with its needed effects, ethambutol may cause some unwanted or undesirable effects. The frequency and severity of these effects is dependant on many factors including dose, duration of therapy and individual susceptibility. Possible unwanted effects include:

• visual disturbances
• stomach upset
• nausea

Uncommon:

• gout (deposits of uric acid in the joints that cause pain in the joints)
• joint pain

Rare:

• abdominal pain
• vomiting
• headache
• dizziness
• mental confusion
• hallucinations

If you are (or suspect you are) experiencing unwanted effects, report them to your doctor or pharmacist.

Ethambutol is an antituberculosis drug. It works by seeping into growing tubercle bacilli, and is thought to impair cell metabolism, halt multiplication of the bacteria, and cause cell death.

Ethambutol use can cause visual problems, but these are generally reversible when the drug is discontinued. Changes in color perception are the first signs of a problem. Notify your doctor if you experience any changes in vision.
During long-term therapy, you may be required to have periodic liver, kidney and blood tests.
Drug Interactions: It is important to tell your doctor and pharmacist of any prescription or over-the-counter medications you are taking. Antacids containing aluminum may alter the absorption of ethambutol. If they must be used, separate their administration by at least 4 hours.
Use is not recommended in the following situations:

• optic neuritis (inflammation of the optic nerve)
• allergy to ethambutol

Caution is recommended in the following situations:

• kidney disease
• cataracts
• diabetic retinopathy (disorder of the retina resulting in impairment or loss of vision)
• other vision problems

Use in pregnancy: Ethambutol can be used in pregnancy but contact your doctor or pharmacist before use.
Use while breastfeeding: Ethambutol passes into breast-milk in small amounts. Contact your doctor or pharmacist before use.