Anti-thyroid Medications

These medicines are used to treat an overactive thyroid gland by decreasing the output of thyroid hormone from the thyroid.

Propylthiouracil (also called PTU)

• PTU blocks the production of thyroid hormone inside the thyroid gland
  
  
• PTU is usually given in divided doses, 2 to 3 times a day
  
  
• Blood levels of thyroid hormone do not drop until the stores of thyroid hormone in the thyroid are depleted, typically after 2-4 weeks
  
  
• Thyroid hormone levels may take 1 to 4 months to normalize
  
  
• Mild side effects include rash, low grade fevers, and itchiness
  
  
• Rare but serious side effects include a reduction in white blood cells, which can prevent the body from fighting off an infection, and hepatitis (liver damage)

Methimazole (Tapazole)

• Similar mechanism and delay of action as PTU
  
  
• Tapazole can be taken once each day
  
  
• Tapazole has similar side effects to PTU

Blood levels of thyroid hormones should be checked every 4 to 6 weeks until hormone levels stabilize