They're responding to television commercials, Internet ads and billboards asking if they have "Low-T," the South Florida Sun Sentinel reported Friday.
Many men have said the male hormone has improved their endurance and virility, but some doctors say they worry the extra testosterone could have side effects and cause long-term problems that have not been thoroughly studied.
There are several potential dangers of the testosterone injections including stroke, testicular atrophy and prostate cancer, Dr. Angelos Manganiotis, a urologist and chief of surgery at Boca Raton Regional Hospital, said.
Men's production of testosterone begins a gradual decline around age 40 in what's called "andropause," which can cause depression, night sweats and fatigue, symptoms similar to women's menopause, doctors say.
As baby boomers grow old, medical and business establishments are discovering a growth industry in men looking to slow their degeneration.
"They want to stay young forever," Manganiotis said. "Men are later to this issue than women are."