More than 50 lawsuits challenging the safety of testosterone drugs have been filed across the country following the launch of a federal investigation into reports of increased heart attack and stroke deaths.

The lawsuits began trickling, and then pouring, into courthouses nationally after the Food and Drug Administration in February said it was reassessing the safety of testosterone replacement drugs, and would investigate rates of stroke, heart attack and death in men using the products. At least two major studies have shown an increase in the danger.

Testosterone creams, patches and gels are approved to treat hypogonadism (low testosterone) in men who suffer from the condition because of an underlying medical issue.

“Many men are given testosterone who don’t need it,” said Dr. Robert Eckel, a past president of the American Heart Association, an endocrinologist and an endowed chair of atherosclerosis at the University of Colorado’s medical school. “They aren’t hypogonadal based on symptoms.”

A January 2014 study published in PLOS One said testosterone therapy doubled the risk of heart attack in men over the age of 65. Last year the Journal of the American Medical Association concluded, following a study of data related to men in the Veterans Affairs health care system, that “the use of testosterone therapy was associated with increased risk of adverse outcomes,” such as heart attack and stroke.

Lawsuits allege the manufactures increased sales through marketing tactics to convince men to testosterone replacement therapy as a solution for problems normally associated with aging. The claims also say the companies failed to properly warn doctors and users about the risks and side effects.

Lawyers for a bulk of these testosterone replacement therapy cases have asked the U.S. Judicial Panel on Multidistrict Litigation, or JPML, to consolidate them to one court, to streamline pre-trial preparation and make it easier for plaintiffs to share resources for discovery. One plea asks for the cases to be heard in Louisiana; another is asking for Illinois. The JPML heard the arguments in at least one plea at the end of May.

Trent Miracle, head of pharmaceutical litigation at the Chicago-based Simmons, Browder, Gianaris, Angelides & Barnerd, said his firm represents at least 250 men affected by testosterone replacement therapy “and that number keeps going up.”

He said many of the men were lured by the marketing, prompting them to see their doctor because of a suppressed libido or lack of energy.

“You have the advertising everywhere you look as some kind of panacea across the board for all your ills, and that’s not true,” he said. “You have a group going to their doctor and saying ‘Hey, I’m seeing the advertising’, and you don’t have doctors who have been told anything by the pharmaceutical companies” about the cardiac dangers.

Billboards, websites and television commercials advertising solutions for “Low T” have cropped up across the country. The market for testosterone-replacing drugs is worth about $2 billion, with predictions that could increase dramatically in coming years.

In February, the consumer advocacy group Public Citizen petitioned the FDA to add a “black box warning” about the increased risks of heart attacks and other cardiovascular dangers to testosterone supplements. The group also wants the FDA to ask manufacturers to send a letter to warn doctors about the side effects.

The group says more than 5 million U.S. prescriptions for testosterone products were filled in 2013. The most common of those, more than 90 percent of the testosterone prescriptions filled last year, include Androgel, Axiron, Testim and Fortesta. Other names for the drug include Androderm, Delatestryl, Striant, Depo-Testosterone and Testopel.

As men age, sperm counts and testosterone rates decrease. That, as well as fatigue and general malaise, can be parts of growing older. But true hypogonadism is a condition marked by other medical conditions, Eckel said, such as decreases in bone density and muscle mass, sexual dysfunction and a decrease in body hair.

To confirm a diagnosis, men should receive a thorough workup from an internist, with at least one blood test early in the day when testosterone levels are highest, along with a check on other hormones. And patients with cardiovascular risks should be under even more scrutiny, he said.

“This shouldn’t be casual medicine,” Eckel said. “If the only reason the guy is in the office is for erectile dysfunction, he shouldn’t be given a prescription for testosterone.”