Drugs used to treat low testosterone should carry strong warnings about the risk of heart attacks and other cardiovascular problems, the consumer advocacy group Public Citizen said on Tuesday.
The group has petitioned the U.S. Food and Drug Administration to add a black box warning, the most serious possible, to the product labels of the drugs.
Testosterone therapy is approved by the FDA for men who lack or have low testosterone in conjunction with an associated medical condition, such as a genetic failure of the testicles to produce testosterone.
Symptoms of low testosterone can include loss of libido, depression, decreased muscle mass and fatigue.
According to Public Citizen, almost 25 percent of men prescribed testosterone didn't previously have a blood test to determine if their level was low.
The group said its petition was based on growing evidence of the risks of heart attacks and other cardiac dangers from studies dating back to 2010 and a recently published analysis of 27 studies going back as far as 20 years.
Of the 27 studies, 14 that were not funded by the pharmaceutical industry showed a "highly significant" increased risk, Public Citizen said. Thirteen were funded by drug companies and those studies showed no increased cardiovascular risk.
Last month, the FDA issued an alert and said it was investigating the risk of stroke, heart attack and death in men taking testosterone drugs based on the recent publication of two studies that suggested increased cardiac risk.
But the FDA said it had not concluded that testosterone does, in fact, increase heart problems.
Dr. Sidney Wolfe, senior adviser at Public Citizen's health group, said the FDA's statement was "reckless" and "a betrayal of the FDA's role as an agency in the U.S. Public Health Service."
"It is quite clear that testosterone treatment increases the risks of cardiovascular diseases, including heart attacks," he said.
FDA officials were not immediately available for comment.
The FDA's alert followed publication of a study in the journal PLOS ONE showing that men over the age of 65 had a two-fold increase in the risk of heart attack within 90 days of filling an initial prescription.
Among men under the age of 65 with a history of heart disease, there was a two-to-three-fold increased risk of heart attack, although there was no increased risk in younger men without a history of heart disease.
In older men, the increased risk was seen, whether or not they had a previous heart disease history.
The market for testosterone treatments currently includes skin patches, short-acting injections and topical gels. AbbVie Inc's AndroGel, the market leader, generated about $1.2 billion in sales in 2012.
"At the current rate of prescribing, almost 13,000 prescriptions a day are filled for testosterone products in this country," Wolfe said. "Each day of delay of the black box warning ensures much more exposure, too often for men who cannot benefit from the drug but will only be exposed to its risks."
The petition also urged the FDA to delay deciding on whether to approve a long-acting testosterone product made by Endo Health Solutions Inc called Aveed.
Aveed has twice been rejected by the FDA based on concerns about injection-site reactions and the risk it could cause blockages in blood vessels in the lungs.
(Reporting by Toni Clarke in Washington; Editing by Bernadette Baum)