# Propylthiouracil

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DRUG INFORMATION

  ADULT
    - Adults The initial dose is 300 mg daily.
      Source: US FDA label for propylthiouracil (Propylthiouracil), section 'dosage and
      administration', retrieved 2026-08-29
    - In patients with severe hyperthyroidism, very large goiters, or both, the initial
      dose may be increased to 400 mg daily; an occasional patient will require 600 to
      900 mg daily initially.
      Source: US FDA label for propylthiouracil (Propylthiouracil), section 'dosage and
      administration', retrieved 2026-08-29
    - The usual maintenance dose is 100 to 150 mg daily.
      Source: US FDA label for propylthiouracil (Propylthiouracil), section 'dosage and
      administration', retrieved 2026-08-29

  CHILD
    - Postmarketing reports of severe liver injury including hepatic failure requiring
      liver transplantation or resulting in death have been reported in the pediatric
      population (see WARNINGS ). No such reports have been observed with methimazole.
      As such, propylthiouracil is not recommended for use in the pediatric population
      except in rare instances in which methimazole is not well-tolerated and surgery or
      radioactive iodine therapy are not appropriate.
      Source: US FDA label for propylthiouracil (Propylthiouracil), section 'pediatric
      use', retrieved 2026-08-29
    - Propylthiouracil is administered orally. The total daily dosage is usually given
      in 3 equal doses at approximately 8-hour intervals. Adults The initial dose is 300
      mg daily. In patients with severe hyperthyroidism, very large goiters, or both,
      the initial dose may be increased to 400 mg daily; an occasional patient will
      require 600 to 900 mg daily initially. The usual maintenance dose is 100 to 150 mg
      daily.
      Source: US FDA label for propylthiouracil (Propylthiouracil), section 'dosage and
      administration', retrieved 2026-08-29
    - Studies evaluating appropriate dosing regimen have not been conducted in the
      pediatric population although general practice would suggest initiation of therapy
      in patients 6 years or older at a dosage of 50 mg daily with careful upward
      titration based on clinical response and evaluation of TSH and free T4 levels.
      Source: US FDA label for propylthiouracil (Propylthiouracil), section 'pediatric
      use', 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 propylthiouracil
      (Propylthiouracil), 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 propylthiouracil
      (Propylthiouracil), retrieved 2026-08-29

  PREGNANCY
    - In pregnant women with untreated or inadequately treated Graves' disease, there is
      an increased risk of adverse events of maternal heart failure, spontaneous
      abortion, preterm birth, stillbirth, and fetal or neonatal hyperthyroidism.
      Source: US FDA label for propylthiouracil (Propylthiouracil), section 'pregnancy',
      retrieved 2026-08-29
    - If propylthiouracil is used during pregnancy, or if the patient becomes pregnant
      while taking propylthiouracil, the patient should be warned of the rare potential
      hazard to the mother and fetus of liver damage.
      Source: US FDA label for propylthiouracil (Propylthiouracil), section 'pregnancy',
      retrieved 2026-08-29
    - Because propylthiouracil crosses placental membranes and can induce goiter and
      cretinism in the developing fetus, it is important that a sufficient, but not
      excessive, dose be given during pregnancy.
      Source: US FDA label for propylthiouracil (Propylthiouracil), section 'pregnancy',
      retrieved 2026-08-29

  BREASTFEEDING
    - Propylthiouracil is present in breast milk to a small extent and therefore likely
      results in clinically insignificant doses to the nursing infant.
      Source: US FDA label for propylthiouracil (Propylthiouracil), section 'nursing
      mothers', retrieved 2026-08-29
    - In one study, nine lactating women were administered 400 mg of propylthiouracil by
      mouth.
      Source: US FDA label for propylthiouracil (Propylthiouracil), section 'nursing
      mothers', retrieved 2026-08-29
    - The mean amount of propylthiouracil excreted during 4 hours after drug
      administration was 0.025% of the administered dose.
      Source: US FDA label for propylthiouracil (Propylthiouracil), section 'nursing
      mothers', retrieved 2026-08-29
```

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