Researchers linked 2,200 deaths of American men from impotence drugs in the last decade, according to the U.S. Food and Drug Administration's Office of Surveillance and Epidemiology.

The death figures are estimates as the number of men taking medications like Viagra and Cialis is between 15 million and 84 million in the U.S. alone, according to the study.

Doctors agree that men should consider the possibility of underlying health problems before resorting to drugs to counter impotence, also known as erectile dysfunction.

"All men over 30 years should have a cardiac risk assessment," said Graham Jackson, a London-based cardiologist and one of the authors of the Princeton Consensus, a set of guidelines for heart patients.

In 2005, a study published in the Journal of the American Medical Association showed men with erectile dysfunction had a 25 percent increased risk of developing heart disease over five years.

In contrast, the new study aimed at focusing on the adverse effects of erectile dysfunction drugs reported from 2000 to 2010. The study found 26,000 reports of serious conditions in patients, such as heart attacks and cardiac failure, all related to erection drugs, prescribed and otherwise.

The most recent study is limited given the available data at FDA. Patients should still know the potential hazards from erectile dysfunction drugs, including those that are ordered online without prescription, said study author Gregory Lowe, a urologist at Ohio State University Medical Center.

Lowe said his study did not distinguish between patients who took prescription versus counterfeit drugs.

"The safest way to go is to have the medication prescribed by your physician and obtained through the traditional pharmacy," he said.

Lowe's findings were published online Oct. 24 in the Journal of Sexual Medicine.

The common causes of erectile dysfunction include diabetes, kidney disease, neurological and vascular diseases, as well as prostate cancer, according to WebMD.com. Other factors that could contribute to male impotence include tobacco, alcohol and drug use, as these substances can damage a person's blood vessels and could possibly restrict blood flow to the penis.