Ethambutol

Mechanism-of-action class: Nucleic Acid Synthesis Inhibitors.

• Ethambutol Hydrochloride Tablets, USP are indicated for the treatment of pulmonary tuberculosis. It should not be used as the sole antituberculous drug, but should be used in conjunction with at least one other antituberculous drug.ICD-10: A15.9

• Ethambutol hydrochloride is contraindicated in patients who are known to be hypersensitive to this drug. It is also contraindicated in patients with known optic neuritis unless clinical judgment determines that it may be used.contraindicated

Ethambutol hydrochloride should not be used alone, in initial treatment or in retreatment. Ethambutol hydrochloride should be administered on a once every 24-hour basis only. Absorption is not significantly altered by administration with food. Therapy, in general, should be continued until bacteriological conversion has become permanent and maximal clinical improvement has occurred. Ethambutol hydrochloride is not recommended for use in pediatric patients under 13 years of age since safe conditions for use have not been established. Initial Treatment In patients who have not received previous antituberculous therapy, administer ethambutol hydrochloride 15 mg/kg (7 mg/lb) of body weight, as a single oral dose once every 24 hours. In the more recent studies, isoniazid has been administered concurrently in a single, daily, oral dose. Retreatment In patients who have received previous antituberculous therapy, administer ethambutol hydrochloride 25 mg/kg (11 mg/lb) of body weight, as a single oral dose once every 24 hours. Concurrently administer at least one other antituberculous drug to which the organisms have been demonstrated to be susceptible by appropriate in vitro tests. Suitable drugs usually consist of those not previously used in the treatment of the patient. After 60 days of ethambutol hydrochloride administration, decrease the dose to 15 mg/kg (7 mg/lb) of body weight, and administer as a single oral dose once every 24 hours. During the period when a patient is on a daily dose of 25 mg/kg, monthly eye examinations are advised.

Ethambutol hydrochloride may produce decreases in visual acuity which appear to be due to optic neuritis. This effect may be related to dose and duration of treatment. This effect is generally reversible when administration of the drug is discontinued promptly. However, irreversible blindness has been reported. (See PRECAUTIONS and ADVERSE REACTIONS ). Liver toxicities including fatalities have been reported (See ADVERSE REACTIONS ). Baseline and periodic assessment of hepatic function should be performed.

Ethambutol hydrochloride may produce decreases in visual acuity, including irreversible blindness, which appear to be due to optic neuritis. Optic neuropathy including optic neuritis or retrobulbar neuritis occurring in association with ethambutol therapy may be characterized by one or more of the following events: decreased visual acuity, scotoma, color blindness, and/or visual defect. These events have also been reported in the absence of a diagnosis of optic or retrobulbar neuritis. Patients should be advised to report promptly to their physician any change in visual acuity. The change in visual acuity may be unilateral or bilateral and hence each eye must be tested separately and both eyes tested together. Testing of visual acuity should be performed before beginning ethambutol hydrochloride therapy and periodically during drug administration, except that it should be done monthly when a patient is on a dosage of more than 15 mg/kg/day. Snellen eye charts are recommended for testing of visual acuity. Studies have shown that there are definite fluctuations of one or two lines of the Snellen chart in the visual acuity of many tuberculous patients not receiving ethambutol hydrochloride. The following table may be useful in interpreting possible changes in visual acuity attributable to ethambutol hydrochloride.

Pregnancy Teratogenic Effects: Pregnancy Category C There are no adequate and well-controlled studies in pregnant women. There are reports of ophthalmic abnormalities occurring in infants born to women on antituberculous therapy that included ethambutol hydrochloride. Ethambutol hydrochloride should be used during pregnancy, only if the benefit justifies the potential risk to the fetus. Ethambutol hydrochloride has been shown to be teratogenic in pregnant mice and rabbits when given in high doses. When pregnant mice or rabbits were treated with high doses of ethambutol hydrochloride, fetal mortality was slightly but not significantly (P>0.05) increased. Female rats treated with ethambutol hydrochloride displayed slight but insignificant (P>0.05) decreases in fertility and litter size. In fetuses born of mice treated with high doses of ethambutol hydrochloride during pregnancy, a low incidence of cleft palate, exencephaly and abnormality of the vertebral column were observed. Minor abnormalities of the cervical vertebra were seen in the newborn of rats treated with high doses of ethambutol hydrochloride during pregnancy. Rabbits receiving high doses of ethambutol hydrochloride during pregnancy gave birth to two fetuses with monophthalmia, one with a shortened right forearm accompanied by bilateral wrist-joint contracture and one with hare lip and cleft palate.

• Nov 6, 1967NDANDA016320Kanchan Hlthcare
• Nov 30, 1999ANDAANDA075095Epic Pharma Llc
• Jun 17, 2009ANDAANDA078939Lupin

1. 1Product Use In Unapproved Indication2128.1%
2. 2Pyrexia1636.3%
3. 3Nausea1284.9%
4. 4Vomiting1204.6%
5. 5Drug Interaction1134.3%
6. 6Drug Intolerance1044.0%
7. 7Cough923.5%
8. 8Diarrhoea883.4%
9. 9Dyspnoea883.4%
10. 10Off Label Use873.3%
11. 11Immune Reconstitution Syndrome863.3%
12. 12Anaemia803.1%
13. 13Pneumonia773.0%
14. 14Mycobacterium Avium Complex Infection752.9%
15. 15Drug Ineffective For Unapproved Indication742.8%

Recent PubMed references pinned to Ethambutol as a MeSH major topic. Citations link to pubmed.ncbi.nlm.nih.gov.

• Ocular toxicity associated with Ethambutol in the South-East Asia Region.
  International ophthalmology · 2026 · Suresh J, Kumar R, Hissar S, et al.
  PMID 42240730DOI 10.1007/s10792-026-04131-6
• Population pharmacokinetics of pyrazinamide and ethambutol in children with tuberculosis with or without HIV.
  Antimicrobial agents and chemotherapy · 2026 · Maranchick NF, Martyn-Dickens C, Enimil A, et al.
  PMID 41770228DOI 10.1128/aac.00909-25
• Ethambutol induces optic neuropathy through SDHB-mediated ferroptosis in retinal ganglion cells via Smad4 pathway.
  Human cell · 2026 · Li Q, Ge W, Zhang Y, et al.
  PMID 41563626DOI 10.1007/s13577-025-01342-4
• Surface-Engineered Ethambutol-Loaded Nanoparticles: Design, Fabrication, and In Vitro-In Vivo Evaluation for Tuberculosis Therapy.
  Molecular pharmaceutics · 2026 · Chokshi NV, Naik J, Bora V, et al.
  PMID 41474383DOI 10.1021/acs.molpharmaceut.5c01018
• Ethambutol-Associated Thrombocytopenia: A Rare Case Report of Drug-Induced Platelet Decline in Tuberculosis Treatment.
  The American journal of case reports · 2025 · Françoise U, Henry K, Sidibe M, et al.
  PMID 41420853DOI 10.12659/AJCR.945090
• Preclinical pharmacokinetics/pharmacodynamics studies defining the role of ethambutol in Mycobacterium kansasii lung disease.
  Antimicrobial agents and chemotherapy · 2026 · Gumbo T, Boorgula GD, Srivastava S, et al.
  PMID 41416787DOI 10.1128/aac.01447-25
• Enhanced antimycobacterial efficacy of simulated inhaled clofazimine versus oral clofazimine in combination with azithromycin and ethambutol in a hollow-fiber system.
  The Journal of antimicrobial chemotherapy · 2026 · Raaijmakers J, Aarnoutse R, Te Brake L, et al.
  PMID 41212061DOI 10.1093/jac/dkaf402
• Effect of introducing ethambutol and integrating drugs into fixed-dose tablets on mortality in tuberculosis patients.
  Transactions of the Royal Society of Tropical Medicine and Hygiene · 2026 · Diaz-Quijano FA, Bartholomay P, Andrade KB, et al.
  PMID 40977297DOI 10.1093/trstmh/traf100

The 10 most recently updated of 195 ClinicalTrials.gov registrations naming Ethambutol as an intervention. Registration is not evidence of efficacy or safety — reference crosswalk only.

• Doxycycline Host-directed Therapy to Improve Lung Function and Decrease Tissue Destruction in Pulmonary Tuberculosis
  Recruiting · Phase 3 · Interventional · 150 enrolled · National University Hospital, Singapore
  NCT05473520updated 2026-06-09
• Trial of a Six-Month Regimen of High-Dose Rifampicin, High-Dose Isoniazid, Linezolid, and Pyrazinamide Versus a Standard Nine-Month Regimen for the Treatment of Adults and Adolescents With Tuberculous Meningitis
  Recruiting · Phase 2 · Interventional · 330 enrolled · National Institute of Allergy and Infectious Diseases (NIAID)
  NCT05383742updated 2026-06-02
• Adjunctive Doxycycline for Central Nervous System Tuberculosis
  Recruiting · Phase 2 · Interventional · 200 enrolled · National University Hospital, Singapore
  NCT06446245updated 2026-06-01
• Shortened Regimen for Drug-susceptible TB in Children
  Recruiting · Phase 3 · Interventional · 860 enrolled · Johns Hopkins University
  NCT06253715updated 2026-06-01
• Short-Course Regimens for DS-PTB in AIDS Patients
  Not yet recruiting · Interventional · 148 enrolled · Shanghai Public Health Clinical Center
  NCT07608172updated 2026-05-27
• Collect Data From Patients Receiving Standardized Anti-tuberculosis Therapy, Collect Monitoring Data, and Evaluate Treatment Efficacy and Potential Adverse Reactions.
  Enrolling by invitation · Observational · 2,215 enrolled · Beijing Chest Hospital
  NCT07607288updated 2026-05-26
• Safety and Efficacy Evaluation of 4-month Regimen of OPC-167832, Delamanid and Bedaquiline in Participants With Drug-Susceptible Pulmonary TB
  Completed · Phase 2 · Interventional · 122 enrolled · Otsuka Pharmaceutical Development & Commercialization, Inc.
  NCT05221502updated 2026-05-26
• Efficacy and Safety Evaluation of Two to Four Months of Treatment With the Combination Regimens of DBOS and PBOS in Adults With Pulmonary Tuberculosis
  Terminated · Phase 2 · Interventional · 93 enrolled · Gates Medical Research Institute
  NCT05971602updated 2026-05-20
• A Trial of Stratified Patient-Centered Treatment Regimens for Active TB (SPECTRA-TB)
  Not yet recruiting · Phase 2 · Interventional · 900 enrolled · National Institute of Allergy and Infectious Diseases (NIAID)
  NCT07595042updated 2026-05-19
• Trial of Novel Regimens for the Treatment of Pulmonary Tuberculosis
  Recruiting · Phase 2 · Interventional · 315 enrolled · National Institute of Allergy and Infectious Diseases (NIAID)
  NCT06192160updated 2026-05-19

Frequently asked questions

How does Ethambutol work?

Mechanism-of-action class: Nucleic Acid Synthesis Inhibitors.

What is Ethambutol used for?

According to FDA labeling, Ethambutol carries indications including: Ethambutol Hydrochloride Tablets, USP are indicated for the treatment of pulmonary tuberculosis. It should not be used as the sole antituberculous drug, but should be used in conjunction with at least one other antituberculous drug.. This is a reference summary of labeled uses, not medical advice or a treatment recommendation.

What class of drug is Ethambutol?

Ethambutol is classified as Other drugs for treatment of tuberculosis, Antimycobacterial, Nucleic Acid Synthesis Inhibitors.

What are the brand names for Ethambutol?

Ethambutol is marketed under brand names including Myambutol.

What are the contraindications for Ethambutol?

Ethambutol labeling lists contraindications including: Ethambutol hydrochloride is contraindicated in patients who are known to be hypersensitive to this drug. It is also contraindicated in patients with known optic neuritis unless clinical judgment determines that it may be used.. Always consult the full prescribing information and a clinician.