To enhance sex drive, an increasing number of elderly men are opting for testosterone therapy - often without prescription.
According to an alarming study, testosterone use has sharply increased among older men in the US and Britain in past decade.
Many such patients appear to have normal testosterone levels and do not meet the clinical guidelines for treatment.
"Over the past decade, older and middle-aged men are increasingly being tested for low testosterone levels and being prescribed testosterone medications, particularly in the US," said co-author J Bradley Layton of the University of North Carolina at Chapel Hill.
The study, published in the Journal of Clinical Endocrinology & Metabolism, suggests that many of those who start taking testosterone may not have a need to do so.
The researchers said that too much testosterone may raise the risk of heart attack, stroke and even death.
The study identified 410,019 American men and 6,858 British men who began taking testosterone between 2000 and 2011.
The researchers also found more than 1.1 million US men and 66,000 British men who had their testosterone levels tested during this time.
Since 2000, the number of men beginning testosterone therapy has almost quadrupled in the US while only increasing by a third in Britain.
"We saw a clear trend where more and more men being tested actually had normal testosterone levels. This is cause for concern as research examines potential risks associated with testosterone use," said Layton.
Since testosterone levels tend to naturally decline as men age, lower levels of the hormone do not necessarily mean that an individual has hypogonadism - a condition that results from low testosterone levels.
Testosterone is a key male sex hormone involved in maintaining sex drive, sperm production and bone health.
Hot flashes, loss of body hair and low libido are some of the symptoms commonly associated with low testosterone.
The testosterone therapy in recommended for adult men suffering from androgen deficiency, or low testosterone, with consistent symptoms.