Ethambutol (Ethambutol Hydrochloride)
Also sold as: Myambutol, Combutol, Servambutol
Pregnancy
Cat B
Lactation
Caution
Schedule
H1
Forms
Tablet 400mg +2
Indications
- Active tuberculosis — intensive phase of DOTS regimen (with rifampicin, isoniazid, pyrazinamide)
- MDR-TB (as part of specialist-designed second-line regimen)
- Non-tuberculous mycobacterial (NTM) infections (with clarithromycin + rifabutin)
Adult Dosing
Tuberculosis — intensive phase
15–20 mg/kg OD (max 1600 mg)
Once daily for 2 months (intensive phase)
Standard dose is 15 mg/kg; 20 mg/kg used in selected cases per specialist; take with food to reduce GI upset
MDR-TB or specialist regimens
Higher doses per MDR-TB specialist guidance
As per specialist-designed MDR-TB regimen
Ophthalmic monitoring mandatory — visual acuity and colour vision before and monthly
Pediatric Dosing
Use with caution in children <13 years as visual acuity testing for optic neuritis may not be reliable; discuss risk-benefit with specialist. If used, monitor closely.
Renal Dose Adjustment
| CrCl / eGFR | Dose Adjustment |
|---|---|
| CrCl ≥50 mL/min | Standard dose: 15–20 mg/kg q24h |
| CrCl 30–50 mL/min | 15 mg/kg q24–36h |
| CrCl 10–30 mL/min | 15 mg/kg q48h |
| CrCl <10 mL/min or haemodialysis | Avoid if possible; if essential, 15 mg/kg q48h with close ophthalmic and renal monitoring |
Hepatic Adjustment
No dose adjustment required for hepatic impairment — ethambutol is primarily renally cleared. Use with caution and monitor LFTs if severe hepatic disease co-exists with TB.
Pregnancy & Lactation
Pregnancy: Category B
Generally considered safe in pregnancy at standard TB doses. Used as part of standard DOTS regimen when clinically indicated. No teratogenicity demonstrated in humans. WHO recommends standard TB treatment including ethambutol in pregnancy.
Lactation: Caution
Excreted in breast milk in small amounts. WHO supports breastfeeding during TB treatment. Infant ophthalmic assessment recommended if prolonged exposure.
Top Drug Interactions
| Interacting Drug | Effect | Severity |
|---|---|---|
| Antacids (aluminium-containing) | Aluminium-containing antacids reduce ethambutol absorption — separate ethambutol dose by at least 4 hours from antacid | Moderate |
| Isoniazid + Rifampicin | Used in combination for additive antitubercular coverage — not a harmful interaction; additive efficacy is the therapeutic goal | Minor |
DoctorScribe — AI Medical Scribe
Stop looking up Ethambutol — just speak the prescription
"Ethambutol as per dose, BD for 5 days." DoctorScribe writes the full prescription with brand, strength, frequency, and route — auto-applies pediatric weight-based dosing and renal adjustments. Try the live demo.
Side Effects
Common
- Visual disturbances — reduced visual acuity, blurred vision, difficulty with colour discrimination (red-green) — early optic neuritis
- Nausea, vomiting, anorexia
- Headache
- Peripheral neuropathy (less common than with isoniazid)
- Arthralgia (joint pains)
Serious / Discontinue If
- Optic neuritis — DOSE-DEPENDENT AND POTENTIALLY IRREVERSIBLE; manifests as reduced visual acuity, red-green colour blindness, central scotoma; STOP DRUG IMMEDIATELY if any visual changes occur
- Peripheral neuropathy
- Hypersensitivity reactions (rash, fever, eosinophilia — rare)
- Thrombocytopenia (rare)
- Hepatotoxicity (mild and uncommon)
Contraindications
- Pre-existing optic neuritis from any cause
- Inability to report visual changes (young children, patients with cognitive impairment — use with extreme caution and close monitoring)
- Hypersensitivity to ethambutol
- Severe renal impairment (CrCl <10 mL/min) — avoid if possible
Available Indian Brands
| Brand | Manufacturer | Price (approx) |
|---|---|---|
| Myambutol 800mg | Wyeth | ₹38/10 tab |
| Combutol 800mg | Lupin | ₹28/10 tab |
| Servambutol 400mg | Macleods | ₹18/10 tab |
Monitoring Required
- Visual acuity assessment (Snellen chart) before starting ethambutol — MANDATORY
- Colour vision testing (Ishihara plates — red-green) before starting — MANDATORY
- Monthly visual acuity and colour vision check during treatment
- Formal ophthalmology review if any visual symptoms develop — STOP DRUG immediately
- Renal function (creatinine, eGFR) before and during treatment — dose-adjust for renal impairment
- LFTs as part of routine TB monitoring panel
Patient Counseling Points
- Report any change in your vision IMMEDIATELY — blurred vision, difficulty distinguishing red from green, or any visual disturbance; stop the medicine and call your doctor the same day
- This medicine can rarely damage the optic nerve (the nerve connecting your eye to your brain) — this risk is the reason vision must be checked monthly
- If you wear glasses, use your correct prescription glasses during vision tests
- Take with food if stomach upset occurs
- Separate from antacids (like Digene, Gelusil) by at least 4 hours
- Do not stop this medicine without telling your doctor
- Tell your doctor immediately if you notice any changes in how well you see or tell colours
Stop Googling drug references mid-consultation
EasyClinic auto-flags Ethambutol interactions, renal cutoffs, and pregnancy warnings the moment you write the prescription. Built-in safety net for every Indian doctor.
Clinically reviewed by: Dr. Anand Kumar, MD (Pulmonology), Chest Physician, TB & Chest Hospital, New Delhi
Last reviewed: 2026-04-30
References
- WHO Treatment of Drug-Susceptible Tuberculosis Guidelines, 2022
- RNTCP DOTS Guidelines, Central TB Division, MoHFW India
- ATS/CDC/IDSA Statement: Treatment of Tuberculosis, 2003 (updated 2016)
- Micromedex Drug Interactions — Ethambutol, 2024
- BNF (British National Formulary) — Ethambutol monograph, 2024