Prescription testosterone treatments such as Rextoro, Axiron, Testopel, and Voglexo Gel are widely advertised as a way to help men improve a low sex drive and reclaim diminished energy. However, concerns have been raised about the risk of heart attack, according to new research.

The increased risk was found in men younger than 65 with a history of heart disease, and in older men even if they didn’t have a history of heart disease. In both groups, the heart attack risk doubled in the 90 days after the men began testosterone therapy.

One study, published in the journal PLoS One, was conducted by a research team that included experts from Consolidated Research, the U.S. National Cancer Institute, and UCLA. The study linked testosterone treatments to a 30% increased risk of heart problems and death.

A 2010 report in the New England Journal of Medicine indicated that a clinical trial of testosterone gel in men over 65 was halted early after an increase in heart attacks and other heart problems occurred in the group using the testosterone supplements.

FDA Wants More Testing Done

The U.S. Food and Drug Administration Bone, Reproductive and Urologic Drugs Advisory Committee (FDA) recently examined the risks and benefits of testosterone therapy and has advised AbbVie, Pfizer, and Eli Lilly & Co. the manufacturers of testosterone drugs taken by millions of men each year, to conduct more tests on the cardiovascular safety of their products and limit indications for use.

On Sept. 17, the panel voted 20-1 that the drug makers need to revise product labels to include stricter language on what health conditions should be treated with the drugs. The FDA also agreed that drug companies should conduct more safety studies to definitively rule out risk of cardiovascular problems.

No Evidence of Benefit

There is no data proving testosterone drugs are effective in treating symptoms men naturally experience as they age, according to the FDA. They also said they couldn’t draw definitive conclusions on potential cardiovascular risk associated with testosterone treatment drugs.

Testsoterone Health Risks

While testosterone replacement therapy has been approved in the U.S. since 1950 for men with medical conditions leading to deficiencies, such as testicular damage due to chemotherapy, more men who have low testosterone for no other reason than age are using the products,

The prospect of narrowing the pool of patients that use Low T drugs by adding label changes doesn’t please pharmaceutical companies who make billions with the drugs. Prescription sales of testosterone treatments increased from $18 million in 1988 to $1.6 billion in 2011. Between 2001 and 2011, the percentage of men older than 40 taking Low T treatments tripled. Despite the rise in popularity of these drugs, medical professionals disagree over the benefits of the drugs.

They also disagree with studies that show a possible increase in the risk of heart problems. Eli Lilly said its assessment of the risk did not support a link to cardiovascular problems, but intended to cooperate based on feedback from the FDA on how to communicate cardiovascular risk to patients.

The issue of testosterone side effects related to the heart made its way into the courts.  In June 2014, a federal judicial panel created a multidistrict litigation (MDL) for testosterone injury lawsuits and moved 44 cases to the U.S. District Court for the Northern District of Illinois. The total number of cases in the testosterone MDL now exceeds 175.