WASHINGTON (AP) -- A consumer advocacy group is calling on the Food and Drug Administration to add a bold warning label to popular testosterone drugs for men in light of growing evidence that the hormone treatments can increase the risk of heart attack.

The group Public Citizen says the agency should immediately add a "black box" warning — the most serious type — to all testosterone medications and require manufacturers to warn physicians about a higher risk of heart attack, stroke and death with the treatments.

The FDA announced last month that it was reviewing the safety of drugs like the blockbuster testosterone gel, AndroGel, in light of two recent studies that showed higher rates of cardiovascular problems in men. The agency said its review was first prompted by a U.S. Veterans Affairs study published in November 2013 that showed a 30 percent increase in stroke, heart attack and death among older men taking testosterone.

In January, a federally funded study of 45,000 men suggested testosterone therapy could double the risk of heart attacks in men 65 and older.

But Public Citizen says studies published as early as 2010 should have prompted FDA action.

"It is quite clear that testosterone treatment increases the risks of cardiovascular diseases, including heart attacks," said Dr. Sidney Wolfe, of Public Citizen's health group.

In his petition to the FDA, Wolfe points to an analysis of 27 testosterone trials published last April. The researchers found that while 13 studies funded by drug companies did not show an increase in heart problems, 14 non-industry funded trials showed a two-fold increase in risk in heart problems.

In addition to the boxed warning, Public Citizen wants the agency to delay an approval decision on an experimental, long-acting testosterone injection called Aveed. The agency is scheduled to make a decision on the Endo Pharmaceuticals drug by Feb. 28.

Public Citizen's petition comes amid a marketing blitz for testosterone gels, patches and injections targeting men who report fatigue, low sex drive or other symptoms commonly associated with aging.

U.S. prescriptions for testosterone therapies have increased more than five-fold in recent years, with sales over $1.6 billion.

FDA labeling on the drugs indicates they are only to be used for men who have abnormally low testosterone caused by a medical condition.

But the latest advertising push by drugmakers is for easy-to-use gels and patches that are aimed at a much broader population of otherwise healthy older men with low levels of testosterone, the male hormone that begins to decline in the body after age 40.

Drugmakers and many doctors claim testosterone therapy can reverse some unpleasant side effects of aging — ranging from insomnia to erectile dysfunction. Those claims are mostly based on short-term studies.

The top-selling product in the field is Abbvie's Androgel, which is applied to the shoulders and arms. Watson Pharmaceuticals markets the Androderm patch, which slowly releases testosterone into the bloodstream. Fortesta is another testosterone gel from Endo Pharmaceuticals, and Eli Lilly's Axiron is an underarm gel that rolls on like deodorant.