Pregnancy: During pregnancy, especially during the 10th and 14th week, when the facial production of hormones begins, an especially careful observation is necessary. In the last third, hyperthyreosis often improves spontaneously, that means a reduction of dose may be possible.
Lactation: The concentration in the milk is maximum 1/10 of the mother serum concentration, that is why for nursing patients with hyperthyroid symptoms, Propylthiouracil is accepted as a means of choice.