Abstract: Methods of using N,N'-disubstituted thiocarbamide compounds for reversibly inhibiting hyperthyroidism are provided. Active compounds reversibly inhibit catalytic iodination without producing sulfenic acid intermediates which can permanently inactivate thyroid peroxidase. By preventing sulfenic acid formation, side effects due to toxicity in liver and bone marrow can be reduced compared to currently used drugs. The compounds can be formulated for administration to a hyperthyroid patient until remission occurs with less risk of possible everdosing.