Recent studies suggest that the popular drug Viagra could be among the risk factors for melanoma skin cancer.

Doctors and medical researchers have found a number of potential causes of skin cancer, with erectile dysfunction drugs like Viagra potentially among them.

Some risks are things that a person has little control over. A family history of melanoma or other skin cancers could indicate a predisposition to the disorder.

Additionally, having many moles on your body could indicate a predisposition to melanoma. Along similar lines, having a depressed immune system, as seen in HIV/AIDS patients and organ transplant recipients, can increase the risk of many cancers, including melanoma.

More directly, exposures to UV radiation, a component of sunlight, radically increase the risk of developing melanoma. Severe sunburns and living near the equator or at high elevations can increase this risk radically. However, medical researchers may have recently found a new potential risk factor for melanoma.

A research study published in JAMA: Internal Medicine this summer revealed that researchers had found an increased risk of melanoma in patients who used Sidenafil, the active ingredient in Viagra.

Researchers relied on a study design called a prospective cohort study, where researchers put together a similar group of patients with one or two differences between them, then follow them and look for different health outcomes.

In this case, patients who took Viagra were found to develop melanoma at a higher rate than others in the cohort.

This type of study cannot go as far as to say  that Viagra is one of the causes of skin cancer. Due to certain limitations in the way the study works, it cannot “prove” that the drug is one of the causes of skin cancer.

However, researchers can say that in their cohort, patients taking Viagra had an increased risk of melanoma. To bolster this conclusion, researchers found that patients taking Viagra did not have an increased risk of other types of skin cancer. This specificity adds a degree of credibility to the study’s conclusions.

Additionally, researchers found that patients with erectile dysfunction who did not take Viagra did not have the same risk, removing a potentially confounding risk and further increasing the credibility of the conclusion that patients taking Viagra have an increased risk of developing melanoma.

Additionally, in vitro — that is, experiments outside of the human body in a laboratory — indicated that there could be a bio-chemical explanation, that Sidenafil interferes with chemicals that normally keep errant cells in check, allowing melanoma to develop.