Men taking erectile dysfunction pills may be adding years to their life, suggests a sweeping observational study published in early January. The research, published on January 13 in The Journal of Sexual Medicine, reported cardioprotective effects from sildenafil, the generic name for Viagra and Revatio. Sildenafil was originally developed as a heart medication before eventually becoming approved for ED. The findings support earlier claims during the drug’s development that it possesses cardiac benefits.

“In general, these drugs appear to be safe in regards to major adverse cardiovascular events,” says lead study author Robert Kloner, a professor of medicine at Keck School of Medicine at the University of Southern California, chief science officer at Huntington Medical Research Institutes, and lead author of the study. However, he cautions that the study only showed an association, not a causal relationship, between the drug and lowered risk of heart problems and mortality. The research was partially funded by Sanofi, a pharmaceutical company that produces the erectile dysfunction medication Cialis.

[Related: Viagra could have been a groundbreaking cure for period cramps]

Sildenafil is a phosphodiesterase type 5 (PDE5) inhibitor. It works by blocking an enzyme in the walls of blood vessels, which allows them to relax and widen, increasing blood flow, most notably in the penis. But it can also improve blood flow to other areas of the body and is currently approved as a treatment for pulmonary hypertension for both men and women in the US. Decades of research in men taking PDE5 inhibitors for erectile dysfunction suggests that the drug could also help treat other heart problems, although most of these studies lacked control groups and involved small sample sizes. Kloner and his colleagues were interested in studying other health benefits the drug provides in a much larger pool that would be more likely to use it—men with ED living in the US.

The study authors analyzed 14 years of medical records of men 18 years and older diagnosed with erectile dysfunction for at least one year. The patients were classified into two groups: The first group included more than 23,000 men who spent one or more years using PDE5 inhibitors like sildenafil, and the second group was made up of more than 48,000 men with no record of ever using these drugs.

Men who had taken PDE5 inhibitors showed a 13-percent lower chance of future heart problems that involve reduced blood flow to the cardiac muscle, such as a heart attack, stroke, or chest pain, versus men who have never taken the medications. What’s more, PDE5 users were 39 percent less likely to die from a cardiovascular-related death, and 25 percent less likely to die from any cause compared to the non-exposed group. 

The amount of pills they took also mattered. Men with ED prescribed the most PD5 inhibitors (an average of 191.2 tablets) showed the most reduced risk of heart issues (55 percent) and premature death (49 percent) than those given the lowest amount of pills (an average of 5.5 tablets). “The encouraging aspect of the study was that nearly all the endpoints were improved in the same direction that is in favor of PDE-5 inhibitor exposure. This finding was consistent across the study,” says Kloner.

“We know loneliness is associated with mortality and poor heart health outcomes.”

— Rena Malik, urologist

At first glance, the positive results might make it seem like everyone should take ED treatments to stay heart-healthy. But that’s not the case, as the observational study design makes it difficult to rule out any other explanations. For one, it only measured the number of pills given to patients, not the number actually taken, says Rigved Tadwalkar, a cardiologist at Providence Saint John’s Health Center in California who was not involved in the research. “Filling a medication does not necessarily equal taking the medication.”

Men who chose to take Viagra could have also been heart-healthier from the start. A doctor may feel hesitant to prescribe the drug to someone with a history of poor cardiovascular health, says Rena Malik, a urologist and associate professor of surgery at the University of Maryland School of Medicine who also was not involved in the study. “When does sex become risky? It’s usually when you have really poor cardiac health, and that’s when you shouldn’t be having much sex.” What’s more, for those engaging in between-the-sheets activity, it may be the exertion itself that’s providing cardiovascular benefits. People who often have sex may already be fitter than someone who is not, Malik explains. “It’s possible they have less chronic pain, are more mobile, and are flexible.” Additionally, being intimate with someone could imply that they’re less lonely than someone without a partner. “We know loneliness is associated with mortality and poor heart health outcomes” Malik notes, all of which could contribute to a higher risk of cardiac-related mortalities.

But both Tadwalkar and Malik agree that the study findings shouldn’t be dismissed, even if there are several confounding variables. “There are many factors that could play a role, but PD5 inhibitors are vasodilators that allow for blood flow, so it makes sense that these could also be protective,” says Malik. She and Tadwalkar further noted that the study was well-executed and adds a lot of value to what we already know about PD5 inhibitors. Tadwalkar underscores that doctors may be more willing to use these drugs in patients with cardiovascular problems who want to take Viagra if there are no significant and harmful reactions to the drug. 

[Related: Research on aphrodisiacs is kind of unsatisfying]

PD5 inhibitors could also be prescribed to protect the heart health of women. While female patients were not part of the study, Kloner says the drugs have the capability of relaxing blood vessels and reducing mortality for them, too. A randomized, placebo-controlled clinical trial will be needed, however, to expand the findings to other populations and make more conclusive recommendations around PD5 inhibitors and any potential cardiac benefits.

“The issue is who is going to pay for a [clinical trial],” says Kloner. Because the drugs are generic, he says there has been low interest from pharmaceutical companies and the government to support a large erectile dysfunction-related analysis that isn’t based on preexisting data. “But perhaps with our study, there will be renewed interest in funding such a study,” he states, “[and possibly] allow for new indications for these drugs for the practice of preventative cardiology.”