Following the countless reports of disturbing side-effects in children who were exposed to testosterone gels, the US Food and Drug Administration (FDA) Thursday asked for the inclusion of a "black box" warning for two prescription topical testosterone gel products - AndroGel form Solvay, and Testim from Auxilium Pharmaceuticals.

Regarding its order of the sternest warning on the two testosterone gels, FDA said their side-effects on young children included problems like improper enlargement of the penis or clitoris, increased libido, early growth of pubic hair, advanced bone age, and antagonistic behavior.

Though in a majority of the cases, the disquieting signs and symptoms reverted after the discontinuation of the use of the gels; in some cases, the effects on the genitalia and bone age lingered on - thereby necessitating invasive diagnostic procedures for the affected children.

Though the gels are approved for use in men who either do not produce testosterone or produce it in negligible amounts, most of the men who use them are not aware of the precautions that need to be taken to protect children from "secondary exposure."

Pointing out the need for responsible use of such medications, Janet Woodcock - director of the FDA's Center for Drug Evaluation and Research - said: "These drugs are approved for an important medical need, but can have serious, unintended side effects if not used properly."