If abdominal pain, nausea, or vomiting occurs during drug therapy for Graves' disease, drug-induced pancreatitis should be considered in the differential diagnosis. If pancreatitis develops during treatment with MMI, switching to PTU should be approached with caution due to the potential for cross-reactivity - and vice versa. In the event that MMI or PTU results in adverse effects, alternative therapeutic modalities should be considered, including radioactive iodine (131I) therapy or surgical interventions. These considerations should be informed by the concomitant increase in IgG4 concentration.
Yamazaki et al. (Wed,) studied this question.