Methylthiouracil is an organosulfur compound that is used antithyroid preparation.

Methylthiouracil is not used clinically in the United States, it has a similar mechanism of action and side effect to that of propylthiouricil.

The clinical effects of the drug to treat the hyperthyroid state can have a lag period of up to two weeks, depending on the stores of thyroglobulin and other factors.

Methylthiouracil is prepared quite simply by condensation of ethyl acetoacetate with thiourea.

[2] Further work in this series shows that better activity was obtained by incorporation of a lipophilic side chain.