(a) Drugs with thyroid hormone activity have been promoted for, and continue to be dispensed and prescribed for, use in the treatment of obesity, although their safety and effectiveness for that use have never been established.
(b) Drugs for human use with thyroid hormone activity are misbranded within the meaning of section 502 of the Federal Food, Drug, and Cosmetic Act unless their labeling bears the following boxed warning at the beginning of the ``Warnings'' section:
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Drugs with thyroid hormone activity, alone or together
with other therapeutic agents, have been used for the
treatment of obesity. In euthyroid patients, doses within
the range of daily hormonal requirements are ineffective for
weight reduction. Larger doses may produce serious or even
life-threatening manifestations of toxicity, particularly
when given in association with sympatho mimetic amines such
as those used for their anorectic effects.
------------------------------------------------------------------ [43 FR 22009, May 23, 1978]