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Isoniazid Dosage

Medically reviewed by Drugs.com. Last updated on Oct 7, 2024.

Applies to the following strengths: 100 mg/mL; 100 mg; 300 mg; 50 mg/5 mL

Usual Adult Dose for Tuberculosis - Extrapulmonary

Pulmonary Tuberculosis without HIV Infection:
OPTION 1:
Initial regimen: 5 mg/kg orally once a day (maximum 300 mg/day) PLUS rifampin, pyrazinamide, and ethambutol/streptomycin


Continuation regimen: 5 mg/kg orally once a day (maximum 300 mg/day) OR 15 mg/kg orally 2 to 3 times a week (maximum 900 mg/day) PLUS rifampin

OPTION 2:
Initial regimen: 5 mg/kg orally once a day (maximum 300 mg/day) PLUS rifampin, pyrazinamide, and streptomycin/ethambutol

Followed by: 15 mg/kg orally 2 times a week (maximum 900 mg/day) PLUS rifampin, pyrazinamide, and streptomycin/ethambutol

Continuation regimen: 15 mg/kg orally 2 times a week (maximum 900 mg/day) PLUS rifampin

OPTION 3:
15 mg/kg orally 3 times a week (maximum 900 mg/day) PLUS rifampin, pyrazinamide, and streptomycin/ethambutol

Extrapulmonary Tuberculosis:
Daily dosing: 5 mg/kg orally once a day

Intermittent dosing: 15 mg/kg orally 2 to 3 times a week

Duration of therapy:

Comments:

Use: Treatment for all forms of susceptible tuberculosis

American Thoracic Society (ATS), US Centers for Disease Control and Prevention (US CDC), and Infectious Diseases Society of America (IDSA) Recommendations:
Up to 40 kg:

Over 40 kg:

Comment: Pyridoxine 25 to 50 mg/day should be considered in all patients at risk of developing neuropathy; patients with peripheral neuropathy may be given 100 mg/day.

Use: Treatment of drug-susceptible tuberculosis
US Department of Health and Human Services (US HHS), National Institutes of Health (NIH), Health Resources and Services Administration (HRSA), and US CDC Recommendations:
LATENT TUBERCULOSIS:
Preferred therapy: 300 mg orally once a day OR 900 mg orally 2 times a week

Alternative therapy: 15 mg/kg orally once a week PLUS rifapentine

DRUG-SUSCEPTIBLE TUBERCULOSIS:
Intensive Phase: 5 mg/kg orally once a day PLUS rifampin/rifabutin, ethambutol, and pyrazinamide

Continuation Phase: 5 mg/kg orally once a day for 5 to 7 days per week PLUS rifampin/rifabutin
Duration of therapy:

DRUG-RESISTANT TUBERCULOSIS:
Initial phase: 5 mg/kg orally once a day PLUS moxifloxacin/levofloxacin, ethambutol, rifampin/rifabutin, pyrazinamide, and an aminoglycoside/capreomycin

Comments:

Uses:

Usual Adult Dose for Tuberculosis - Active

Pulmonary Tuberculosis without HIV Infection:
OPTION 1:
Initial regimen: 5 mg/kg orally once a day (maximum 300 mg/day) PLUS rifampin, pyrazinamide, and ethambutol/streptomycin


Continuation regimen: 5 mg/kg orally once a day (maximum 300 mg/day) OR 15 mg/kg orally 2 to 3 times a week (maximum 900 mg/day) PLUS rifampin

OPTION 2:
Initial regimen: 5 mg/kg orally once a day (maximum 300 mg/day) PLUS rifampin, pyrazinamide, and streptomycin/ethambutol

Followed by: 15 mg/kg orally 2 times a week (maximum 900 mg/day) PLUS rifampin, pyrazinamide, and streptomycin/ethambutol

Continuation regimen: 15 mg/kg orally 2 times a week (maximum 900 mg/day) PLUS rifampin

OPTION 3:
15 mg/kg orally 3 times a week (maximum 900 mg/day) PLUS rifampin, pyrazinamide, and streptomycin/ethambutol

Extrapulmonary Tuberculosis:
Daily dosing: 5 mg/kg orally once a day

Intermittent dosing: 15 mg/kg orally 2 to 3 times a week

Duration of therapy:

Comments:

Use: Treatment for all forms of susceptible tuberculosis

American Thoracic Society (ATS), US Centers for Disease Control and Prevention (US CDC), and Infectious Diseases Society of America (IDSA) Recommendations:
Up to 40 kg:

Over 40 kg:

Comment: Pyridoxine 25 to 50 mg/day should be considered in all patients at risk of developing neuropathy; patients with peripheral neuropathy may be given 100 mg/day.

Use: Treatment of drug-susceptible tuberculosis
US Department of Health and Human Services (US HHS), National Institutes of Health (NIH), Health Resources and Services Administration (HRSA), and US CDC Recommendations:
LATENT TUBERCULOSIS:
Preferred therapy: 300 mg orally once a day OR 900 mg orally 2 times a week

Alternative therapy: 15 mg/kg orally once a week PLUS rifapentine

DRUG-SUSCEPTIBLE TUBERCULOSIS:
Intensive Phase: 5 mg/kg orally once a day PLUS rifampin/rifabutin, ethambutol, and pyrazinamide

Continuation Phase: 5 mg/kg orally once a day for 5 to 7 days per week PLUS rifampin/rifabutin
Duration of therapy:

DRUG-RESISTANT TUBERCULOSIS:
Initial phase: 5 mg/kg orally once a day PLUS moxifloxacin/levofloxacin, ethambutol, rifampin/rifabutin, pyrazinamide, and an aminoglycoside/capreomycin

Comments:

Uses:

Usual Adult Dose for Tuberculosis - Latent

Pulmonary Tuberculosis without HIV Infection:
OPTION 1:
Initial regimen: 5 mg/kg orally once a day (maximum 300 mg/day) PLUS rifampin, pyrazinamide, and ethambutol/streptomycin


Continuation regimen: 5 mg/kg orally once a day (maximum 300 mg/day) OR 15 mg/kg orally 2 to 3 times a week (maximum 900 mg/day) PLUS rifampin

OPTION 2:
Initial regimen: 5 mg/kg orally once a day (maximum 300 mg/day) PLUS rifampin, pyrazinamide, and streptomycin/ethambutol

Followed by: 15 mg/kg orally 2 times a week (maximum 900 mg/day) PLUS rifampin, pyrazinamide, and streptomycin/ethambutol

Continuation regimen: 15 mg/kg orally 2 times a week (maximum 900 mg/day) PLUS rifampin

OPTION 3:
15 mg/kg orally 3 times a week (maximum 900 mg/day) PLUS rifampin, pyrazinamide, and streptomycin/ethambutol

Extrapulmonary Tuberculosis:
Daily dosing: 5 mg/kg orally once a day

Intermittent dosing: 15 mg/kg orally 2 to 3 times a week

Duration of therapy:

Comments:

Use: Treatment for all forms of susceptible tuberculosis

American Thoracic Society (ATS), US Centers for Disease Control and Prevention (US CDC), and Infectious Diseases Society of America (IDSA) Recommendations:
Up to 40 kg:

Over 40 kg:

Comment: Pyridoxine 25 to 50 mg/day should be considered in all patients at risk of developing neuropathy; patients with peripheral neuropathy may be given 100 mg/day.

Use: Treatment of drug-susceptible tuberculosis
US Department of Health and Human Services (US HHS), National Institutes of Health (NIH), Health Resources and Services Administration (HRSA), and US CDC Recommendations:
LATENT TUBERCULOSIS:
Preferred therapy: 300 mg orally once a day OR 900 mg orally 2 times a week

Alternative therapy: 15 mg/kg orally once a week PLUS rifapentine

DRUG-SUSCEPTIBLE TUBERCULOSIS:
Intensive Phase: 5 mg/kg orally once a day PLUS rifampin/rifabutin, ethambutol, and pyrazinamide

Continuation Phase: 5 mg/kg orally once a day for 5 to 7 days per week PLUS rifampin/rifabutin
Duration of therapy:

DRUG-RESISTANT TUBERCULOSIS:
Initial phase: 5 mg/kg orally once a day PLUS moxifloxacin/levofloxacin, ethambutol, rifampin/rifabutin, pyrazinamide, and an aminoglycoside/capreomycin

Comments:

Uses:

Usual Adult Dose for Tuberculosis - Prophylaxis

Adults over 30 kg: 300 mg orally once a day

Duration of therapy:


Comments:

Uses:
Preventive therapy in:

US HHS, NIH, HRSA, and US CDC Recommendations:
Preferred choice: 300 mg orally once a day OR 900 mg orally 2 times a week

Alternative choice: 900 mg orally once a week PLUS rifapentine

Comments:

Uses:

Usual Adult Dose for Mycobacterium kansasii

ATS and IDSA Recommendations:
5 mg/kg orally once a day
Maximum dose: 300 mg/day
Duration of therapy: 18 months

Comment: Patients should have at least 12 months of negative sputum cultures.

Use: Treatment of Mycobacterium kansasii pulmonary disease

Usual Pediatric Dose for Tuberculosis - Extrapulmonary

PULMONARY TUBERCULOSIS WITHOUT HIV INFECTION:
Option 1:
Initial regimen: 10 to 15 mg/kg IM or orally once a day (maximum 300 mg/day) PLUS rifampin, pyrazinamide, and ethambutol/streptomycin


Continuation regimen: 10 to 15 mg/kg IM or orally once a day (maximum 300 mg/day) OR 20 to 40 mg/kg IM or orally 2 to 3 times a week (maximum 900 mg/day) PLUS rifampin

Option 2:
Initial regimen: 10 to 15 mg/kg IM or orally once a day (maximum 300 mg/day) PLUS rifampin, pyrazinamide, and streptomycin/ethambutol

Followed by: 20 to 40 mg/kg IM or orally 2 times a week (maximum 900 mg/day) PLUS rifampin, pyrazinamide, and streptomycin/ethambutol

Continuation regimen: 20 to 40 mg/kg IM or orally 2 times a week (maximum 900 mg/day) PLUS rifampin

Option 3:
20 to 40 mg/kg IM or orally 3 times a week (maximum 900 mg/day) PLUS rifampin, pyrazinamide, and streptomycin/ethambutol

EXTRAPULMONARY TUBERCULOSIS:
Daily dosing: 10 to 15 mg/kg IM or orally once a day

Intermittent dosing: 20 to 40 mg/kg IM or orally 2 to 3 times a week

Duration of therapy:

Comments:

Use: Treatment for all forms of susceptible tuberculosis

American Academy of Pediatrics (AAP) Recommendations:
Infants, Children, and Adolescents:
Daily dosing: 10 to 15 mg/kg orally once a day

Intermittent dosing: 20 to 30 mg orally 2 times a week

Duration of therapy:

Comments:

Uses:

ATS, US CDC, and IDSA Recommendations:
Less than 15 years OR up to 40 kg:

15 years and older AND/OR over 40 kg:

Comment: Pyridoxine 25 to 50 mg/day should be considered in all patients at risk of developing neuropathy; patients with peripheral neuropathy may be given 100 mg/day.

Use: Treatment of drug-susceptible tuberculosis

US HHS, NIH, HRSA, and US CDC Recommendations:
Children:
DRUG-SUSCEPTIBLE TUBERCULOSIS:
Intensive Phase: 10 to 15 mg/kg orally once a day PLUS rifampin, pyrazinamide, and ethambutol
Maximum dose: 300 mg/day
Duration of therapy: 2 months

Continuation Phase: 10 to 15 mg/kg (up to 300 mg/day) orally once a day PLUS rifampin OR 20 to 30 mg/kg IM or orally 3 times a week

Duration of therapy:

Comment: The total duration of treatment is at least 12 months for minimal disease, and 18 to 24 months after non-bacteriological diagnosis or after culture conversion.

Uses:

Usual Pediatric Dose for Tuberculosis - Active

PULMONARY TUBERCULOSIS WITHOUT HIV INFECTION:
Option 1:
Initial regimen: 10 to 15 mg/kg IM or orally once a day (maximum 300 mg/day) PLUS rifampin, pyrazinamide, and ethambutol/streptomycin


Continuation regimen: 10 to 15 mg/kg IM or orally once a day (maximum 300 mg/day) OR 20 to 40 mg/kg IM or orally 2 to 3 times a week (maximum 900 mg/day) PLUS rifampin

Option 2:
Initial regimen: 10 to 15 mg/kg IM or orally once a day (maximum 300 mg/day) PLUS rifampin, pyrazinamide, and streptomycin/ethambutol

Followed by: 20 to 40 mg/kg IM or orally 2 times a week (maximum 900 mg/day) PLUS rifampin, pyrazinamide, and streptomycin/ethambutol

Continuation regimen: 20 to 40 mg/kg IM or orally 2 times a week (maximum 900 mg/day) PLUS rifampin

Option 3:
20 to 40 mg/kg IM or orally 3 times a week (maximum 900 mg/day) PLUS rifampin, pyrazinamide, and streptomycin/ethambutol

EXTRAPULMONARY TUBERCULOSIS:
Daily dosing: 10 to 15 mg/kg IM or orally once a day

Intermittent dosing: 20 to 40 mg/kg IM or orally 2 to 3 times a week

Duration of therapy:

Comments:

Use: Treatment for all forms of susceptible tuberculosis

American Academy of Pediatrics (AAP) Recommendations:
Infants, Children, and Adolescents:
Daily dosing: 10 to 15 mg/kg orally once a day

Intermittent dosing: 20 to 30 mg orally 2 times a week

Duration of therapy:

Comments:

Uses:

ATS, US CDC, and IDSA Recommendations:
Less than 15 years OR up to 40 kg:

15 years and older AND/OR over 40 kg:

Comment: Pyridoxine 25 to 50 mg/day should be considered in all patients at risk of developing neuropathy; patients with peripheral neuropathy may be given 100 mg/day.

Use: Treatment of drug-susceptible tuberculosis

US HHS, NIH, HRSA, and US CDC Recommendations:
Children:
DRUG-SUSCEPTIBLE TUBERCULOSIS:
Intensive Phase: 10 to 15 mg/kg orally once a day PLUS rifampin, pyrazinamide, and ethambutol
Maximum dose: 300 mg/day
Duration of therapy: 2 months

Continuation Phase: 10 to 15 mg/kg (up to 300 mg/day) orally once a day PLUS rifampin OR 20 to 30 mg/kg IM or orally 3 times a week

Duration of therapy:

Comment: The total duration of treatment is at least 12 months for minimal disease, and 18 to 24 months after non-bacteriological diagnosis or after culture conversion.

Uses:

Usual Pediatric Dose for Tuberculosis - Latent

PULMONARY TUBERCULOSIS WITHOUT HIV INFECTION:
Option 1:
Initial regimen: 10 to 15 mg/kg IM or orally once a day (maximum 300 mg/day) PLUS rifampin, pyrazinamide, and ethambutol/streptomycin


Continuation regimen: 10 to 15 mg/kg IM or orally once a day (maximum 300 mg/day) OR 20 to 40 mg/kg IM or orally 2 to 3 times a week (maximum 900 mg/day) PLUS rifampin

Option 2:
Initial regimen: 10 to 15 mg/kg IM or orally once a day (maximum 300 mg/day) PLUS rifampin, pyrazinamide, and streptomycin/ethambutol

Followed by: 20 to 40 mg/kg IM or orally 2 times a week (maximum 900 mg/day) PLUS rifampin, pyrazinamide, and streptomycin/ethambutol

Continuation regimen: 20 to 40 mg/kg IM or orally 2 times a week (maximum 900 mg/day) PLUS rifampin

Option 3:
20 to 40 mg/kg IM or orally 3 times a week (maximum 900 mg/day) PLUS rifampin, pyrazinamide, and streptomycin/ethambutol

EXTRAPULMONARY TUBERCULOSIS:
Daily dosing: 10 to 15 mg/kg IM or orally once a day

Intermittent dosing: 20 to 40 mg/kg IM or orally 2 to 3 times a week

Duration of therapy:

Comments:

Use: Treatment for all forms of susceptible tuberculosis

American Academy of Pediatrics (AAP) Recommendations:
Infants, Children, and Adolescents:
Daily dosing: 10 to 15 mg/kg orally once a day

Intermittent dosing: 20 to 30 mg orally 2 times a week

Duration of therapy:

Comments:

Uses:

ATS, US CDC, and IDSA Recommendations:
Less than 15 years OR up to 40 kg:

15 years and older AND/OR over 40 kg:

Comment: Pyridoxine 25 to 50 mg/day should be considered in all patients at risk of developing neuropathy; patients with peripheral neuropathy may be given 100 mg/day.

Use: Treatment of drug-susceptible tuberculosis

US HHS, NIH, HRSA, and US CDC Recommendations:
Children:
DRUG-SUSCEPTIBLE TUBERCULOSIS:
Intensive Phase: 10 to 15 mg/kg orally once a day PLUS rifampin, pyrazinamide, and ethambutol
Maximum dose: 300 mg/day
Duration of therapy: 2 months

Continuation Phase: 10 to 15 mg/kg (up to 300 mg/day) orally once a day PLUS rifampin OR 20 to 30 mg/kg IM or orally 3 times a week

Duration of therapy:

Comment: The total duration of treatment is at least 12 months for minimal disease, and 18 to 24 months after non-bacteriological diagnosis or after culture conversion.

Uses:

Usual Pediatric Dose for Tuberculous Meningitis

PULMONARY TUBERCULOSIS WITHOUT HIV INFECTION:
Option 1:
Initial regimen: 10 to 15 mg/kg IM or orally once a day (maximum 300 mg/day) PLUS rifampin, pyrazinamide, and ethambutol/streptomycin


Continuation regimen: 10 to 15 mg/kg IM or orally once a day (maximum 300 mg/day) OR 20 to 40 mg/kg IM or orally 2 to 3 times a week (maximum 900 mg/day) PLUS rifampin

Option 2:
Initial regimen: 10 to 15 mg/kg IM or orally once a day (maximum 300 mg/day) PLUS rifampin, pyrazinamide, and streptomycin/ethambutol

Followed by: 20 to 40 mg/kg IM or orally 2 times a week (maximum 900 mg/day) PLUS rifampin, pyrazinamide, and streptomycin/ethambutol

Continuation regimen: 20 to 40 mg/kg IM or orally 2 times a week (maximum 900 mg/day) PLUS rifampin

Option 3:
20 to 40 mg/kg IM or orally 3 times a week (maximum 900 mg/day) PLUS rifampin, pyrazinamide, and streptomycin/ethambutol

EXTRAPULMONARY TUBERCULOSIS:
Daily dosing: 10 to 15 mg/kg IM or orally once a day

Intermittent dosing: 20 to 40 mg/kg IM or orally 2 to 3 times a week

Duration of therapy:

Comments:

Use: Treatment for all forms of susceptible tuberculosis

American Academy of Pediatrics (AAP) Recommendations:
Infants, Children, and Adolescents:
Daily dosing: 10 to 15 mg/kg orally once a day

Intermittent dosing: 20 to 30 mg orally 2 times a week

Duration of therapy:

Comments:

Uses:

ATS, US CDC, and IDSA Recommendations:
Less than 15 years OR up to 40 kg:

15 years and older AND/OR over 40 kg:

Comment: Pyridoxine 25 to 50 mg/day should be considered in all patients at risk of developing neuropathy; patients with peripheral neuropathy may be given 100 mg/day.

Use: Treatment of drug-susceptible tuberculosis

US HHS, NIH, HRSA, and US CDC Recommendations:
Children:
DRUG-SUSCEPTIBLE TUBERCULOSIS:
Intensive Phase: 10 to 15 mg/kg orally once a day PLUS rifampin, pyrazinamide, and ethambutol
Maximum dose: 300 mg/day
Duration of therapy: 2 months

Continuation Phase: 10 to 15 mg/kg (up to 300 mg/day) orally once a day PLUS rifampin OR 20 to 30 mg/kg IM or orally 3 times a week

Duration of therapy:

Comment: The total duration of treatment is at least 12 months for minimal disease, and 18 to 24 months after non-bacteriological diagnosis or after culture conversion.

Uses:

Usual Pediatric Dose for Tuberculosis - Prophylaxis

Infants and children:
Daily dosing: 10 mg/kg IM or orally once a day


Intermittent dosing: 20 to 30 mg/kg IM or orally 2 times a week

Duration of therapy:

Comments:

Uses:
Preventive therapy in:

US HHS, NIH, HRSA, and US CDC Recommendations:
Children:
First choice: 10 to 15 mg/kg orally once a day
Maximum dose: 300 mg/day
Duration of therapy: 9 months

Alternative choices:
Daily dosing: 10 to 15 mg/kg orally once a day PLUS rifampin
Maximum dose: 300 mg/day
Duration of therapy: 3 to 4 months

Intermittent dosing: 20 to 30 mg/kg orally 2 times a week
Maximum dose: 900 mg/day
Duration of therapy: 9 months

Comments:

Uses:

Renal Dose Adjustments

Mild to moderate renal dysfunction: Data not available
Severe renal dysfunction: Frequent monitoring recommended.

ATS, US CDC, and IDSA Recommendations:
CrCl less than 30 mL/min: 300 mg IM, IV, or orally once a day OR 900 mg IM, IV, or orally 3 times a week

Liver Dose Adjustments

Use with caution.
Active chronic liver disease: Frequent monitoring recommended.
Acute liver disease of any etiology: Contraindicated
Patients with a previous drug-associated liver injury: Contraindicated

During treatment:
Transaminase values exceeding 3 to 5 times the upper limit of normal (3 to 5 x ULN): Temporarily discontinue this drug; restarting therapy should be given consideration.

Precautions

US BOXED WARNINGS:


CONTRAINDICATIONS:

Consult WARNINGS section for additional precautions.

Dialysis

Data not available

ATS, US CDC, and IDSA Recommendations:
Hemodialysis: 300 mg IM, IV, or orally once a day OR 900 mg IM, IV, or orally 3 times a week
Peritoneal dialysis: Data not available

Other Comments

Administration advice:


Storage requirements:

General:

Monitoring:

Patient advice:

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.