Isoniazid

DRUG INFORMATION

  ADULT
    - Adults over 30 Kg: 300 mg per day in a single dose.
      Source: US FDA label for isoniazid (isoniazid), section 'dosage and
      administration', retrieved 2026-08-29
    - In situations where adherence with daily preventative therapy cannot be assured,
      20 mg/kg to 30 mg/kg (not to exceed 900 mg) twice weekly under the direct
      observation of a health care worker at the time of administration 8 .
      Source: US FDA label for isoniazid (isoniazid), section 'dosage and
      administration', retrieved 2026-08-29

  CHILD
    - Infants and Children 10 mg/kg (up to 300 mg daily) in a single dose.
      Source: US FDA label for isoniazid (isoniazid), section 'dosage and
      administration', retrieved 2026-08-29
    - In situations where adherence with daily preventative therapy cannot be assured,
      20 mg/kg to 30 mg/kg (not to exceed 900 mg) twice weekly under the direct
      observation of a health care worker at the time of administration 8 .
      Source: US FDA label for isoniazid (isoniazid), section 'dosage and
      administration', retrieved 2026-08-29

  RENAL IMPAIRMENT
    - No kidney-impairment dose in this label. Not a statement that none is needed.
      Source: Read and found silent: the US FDA label for isoniazid (isoniazid),
      retrieved 2026-08-29

  HEPATIC IMPAIRMENT
    - No liver-impairment dose in this label. Not a statement that none is needed.
      Source: Read and found silent: the US FDA label for isoniazid (isoniazid),
      retrieved 2026-08-29

  PREGNANCY
    - Teratogenic Effects Pregnancy Category C Isoniazid has been shown to have an
      embryocidal effect in rats and rabbits when given orally during pregnancy.
      Source: US FDA label for isoniazid (isoniazid), section 'pregnancy', retrieved
      2026-08-29
    - Isoniazid was not teratogenic in reproduction studies in mice, rats and rabbits.
      Source: US FDA label for isoniazid (isoniazid), section 'pregnancy', retrieved
      2026-08-29
    - There are no adequate and well-controlled studies in pregnant women.
      Source: US FDA label for isoniazid (isoniazid), section 'pregnancy', retrieved
      2026-08-29

  BREASTFEEDING
    - The small concentrations of isoniazid in breast milk do not produce toxicity in
      the nursing newborn; therefore, breast feeding should not be discouraged.
      Source: US FDA label for isoniazid (isoniazid), section 'nursing mothers',
      retrieved 2026-08-29
    - However, because levels of isoniazid are so low in breast milk, they can not be
      relied upon for prophylaxis or therapy of nursing infants.
      Source: US FDA label for isoniazid (isoniazid), section 'nursing mothers',
      retrieved 2026-08-29