• Type: Anti-TB
  • Dosage Forms:
  • Routes of Administration: PO, IM
  • Common Trade Names: INH

Adult Dosing

  • Typically 5 mg/kg (or 300mg) daily

Pediatric Dosing

  • ≤40 kg: 10-15 mg/kg daily, maximum 300mg/dose
  • >40kg: 5 mg/kg daily max 300mg/dose

Special Populations

Pregnancy Rating

  • Category A

Lactation risk

  • Considered compatible with breast feeding[1]

Renal Dosing

  • No adjustment

Hepatic Dosing

  • No official adjustment necessary per manufacturer's labeling but use with caution in patient's with preexisting liver disease


  • Allergy/hypersensitivity to class/drug
  • Prior history of hepatic injury or severe adverse reaction to isoniazid
  • Acute liver disease

Adverse Reactions


  • Increased serum transaminases


  • Half-life: Fast acetylators: 30 to 100 minutes, slow acetylators: 2 to 5 hours
  • Metabolism: Hepatic
  • Excretion: Mostly urine

Mechanism of Action

  • Inhibits synthesis of mycoloic acids (essential bacterial cell wall component)


See Also


  • Nahid P, Dorman SE, Alipanah N, et al. Official American Thoracic Society/Centers for Disease Control and Prevention/Infectious Diseases Society of America Clinical Practice Guidelines: Treatment of Drug-Susceptible Tuberculosis. Clin Infect Dis. 2016;63(7):e147-e195.
  • Uptodate
  1. World Health Organization (WHO). Breastfeeding and maternal medication, recommendations for drugs in the eleventh WHO model list of essential drugs. 2002.
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