The number of middle-aged men with prescriptions for testosterone is climbing rapidly, raising concerns that increasing numbers of men are abusing the powerful hormone to boost their libidos and feel younger, UTMB researchers reported on Monday. Jacques Baillargeon, the lead author of the new research, said that the safety of long-term testosterone use had yet to be established in good studies. “I think these relatively healthy men who are starting testosterone at age 40 are potentially going to be exposed for a very long time, and we don’t know what the risks are,” said Baillargeon. The research appears in the June issue of JAMA Internal Medicine. The news is receiving widespread attention, also appearing in Yahoo! News, the Houston Chronicle, NBC News, Fox News and U.S. News and World Report, among other popular outlets.