BMA Concise Guide to Medicine & Drugs


Brand name None

Used in the following combined preparations None


Drug group Antituberculous drug

Overdose danger rating Medium

Dependence rating Low

Prescription needed Yes

Available as generic Yes


Ethambutol is an antibiotic used in the treatment of tuberculosis. It is combined with other antituberculous drugs to enhance its effect and reduce the risk of the infection becoming drug resistant. Ethambutol is not used in all cases of tuberculosis. It is more likely to be used in people with a history of tuberculosis; those with a low immune status; and in those in whom the infection may be caused by a resistant organism. Although the drug has few common adverse effects, it may occasionally cause optic neuritis, a type of eye damage leading to blurring and fading of vision. As a result, ethambutol is not usually prescribed for children under six years of age or for other patients who are unable to communicate their symptoms adequately. Before starting treatment, a full ophthalmic examination is recommended.


Your drug prescription is tailored for you. Do not alter dosage without checking with your doctor.

How taken/used Tablets.

Frequency and timing of doses Once daily.

Adult dosage range According to body weight.

Onset of effect It may take several days for symptoms to improve.

Duration of action Up to 24 hours.

Diet advice None.

Storage Keep in original container at room temperature out of the reach of children.

Missed dose Take as soon as you remember. If your next dose is due within 6 hours, take a single dose now and skip the next.

Stopping the drug Take the full course. Even if you feel better the original infection may still be present and may recur if treatment is stopped too soon.

Exceeding the dose An occasional unintentional extra dose is unlikely to cause problems. Large overdoses may cause headache and abdominal pain. Notify your doctor.


Side effects are uncommon with ethambutol but are more likely after prolonged treatment with high doses. They include nausea, vomiting, dizziness, and numbness or tingling in the hands or feet; discuss with your doctor if any of these are severe. If a rash or itching develops, stop taking the drug and consult your doctor. If you develop blurred vision, eye pain, or loss of colour vision, stop taking the drug and seek prompt medical attention.


Antacids Those containing aluminium salts may decrease levels of ethambutol and should be taken at least 2 hours before ethambutol or 4 hours after.


Be sure to tell your doctor if:

· You have a kidney problem.

· You have cataracts or other eye problems.

· You have gout.

· You have had a previous allergic reaction to this drug.

· You are taking other medicines.

Pregnancy No evidence of risk. Discuss with your doctor.

Breast-feeding The drug passes into the breast milk, but at normal doses adverse effects on the baby are unlikely. Discuss with your doctor.

Infants and children Not generally prescribed under 6 years unless the child can reliably report any vision changes.

Over 60 Increased likelihood of adverse effects. Reduced dose may therefore be necessary.

Driving and hazardous work Avoid such activities until you have learned how ethambutol affects you because the drug may cause dizziness.

Alcohol No known problems.


Prolonged use may increase the risk of eye damage.

Monitoring Periodic eye tests are usually necessary.