List of products in the National Drug Code with proprietary name natesto. This medication is used by men who do not make enough of a natural substance called testosterone (hypogonadism). Testosterone belongs to a class of drugs known as androgens. Testosterone helps the body to develop and maintain male sexual characteristics (masculinity), such as a deep voice and body hair. It also helps to maintain muscle and prevent bone loss, and is necessary for natural sexual ability/desire. This drug should not be used by women.