Men who used either a low dose or a conventional dose of testosterone gel showed no improvements in their sexual function during the course of the year-long study, compared with men who used placebo gel.
The findings were presented at the annual meeting of the American Society for Reproductive Medicine in Orlando, Fla.
"It appears that testosterone supplementation will not improve ED, though it may have other benefits on sexual function that were not evaluated with this data," says study researcher Lauren W. Roth, MD, an obstetrician/gynecologist at the University of Colorado in Denver, in an email.
Sexual function is one of many reasons that many men are turning to testosterone therapy. With a laundry list of promises from a boost in sex drive and more energy to an increase in muscle mass and mental acuity, testosterone therapy can be tempting for many men who want to feel and look younger than they do.
But, according to some experts, the hormone may be more harmful than helpful for some men.
"I am quite concerned about the rampant use of testosterone replacement therapy for very soft indications," says Rebecca Sokol, MD. She is a professor of medicine and obstetrics and gynecology and the director of the andrology program at the Keck School of Medicine of the University of Southern California in Los Angeles. "It is very much a buyer beware situation."
"We have to be very cautious about who we do and do not start on testosterone," Sokol says.
There are risks attached to the use of testosterone, Sokol says. "This hormone may cause the prostate gland to increase in size, and there is also the theoretic risk that we can stimulate the growth of cancer cells in the prostate. We have been looking carefully to see if testosterone initiates prostate cancer and there is no data to indicate that it does at this point."
Testosterone may also increase levels of LDL "bad" cholesterol while decreasing levels of HDL "good" cholesterol, she says.
Men who are considering taking testosterone need to weigh the pros and cons carefully with their doctor.
"The patient really needs to be evaluated by a physician who is an expert in hormones and male reproduction," Sokol says. "The indication for treatment needs to be very clear and verified by evaluation and physical exam."