A drug taken by millions of men for erectile dysfunction may also slow the spread of cancer. Researchers found that sildenafil, the active ingredient in Viagra, appears to block cancer cells from accessing cholesterol, a building block tumors use to metastasize and travel through the body.
The findings were published in the journal Cancer Research. The study was led by researchers from the Weizmann Institute of Science in Israel, working with scientists from Clalit Health Services, Israel's largest health organization. The U.S. National Cancer Institute also participated, along with physicians from Clalit's Beilinson and Hasharon Hospitals.
The research team examined laboratory mouse models of cancer and cultures of cancer cells from human subjects. They also analyzed more than 20 years of clinical data. Male participants who had used Viagra before being diagnosed with cancer had better overall survival rates than those who had not taken the drug. The survival rate was even higher for males who took both Viagra and statins.
The study did not break down results by cancer type. Samah Hayek, a senior epidemiologist at the Clalit Research Institute and a co-author of the study, explained the scope of the analysis. "We evaluated the association between pre-cancer diagnosis use and overall survival across a large cohort of cancer patients rather within specific cancer types," Hayek told Healthline. "Therefore, we cannot conclude whether the association is stronger for one cancer than another."
The study population was also limited almost entirely to men, which reflects how the drug is prescribed. "Our retrospective analysis included mainly men because sildenafil is predominantly prescribed to men," said Hayek. "As a result, we cannot determine from our clinical data whether a similar association would be observed in women."
Hayek said more research, including clinical trials, is needed before sildenafil could become part of standard cancer treatment.
An outside expert who reviewed the study described it as promising. S. Adam Ramin, a urologist, urologic oncologist, and medical director of Urology Cancer Specialists in Los Angeles, was not involved in the research. "This is an interesting study, and it was well-designed," Ramin told Healthline. "It appears to have real applications in real-world situations, so it shows promise."
The connection between sildenafil and cancer survival adds to a growing body of research examining whether existing drugs approved for other conditions might have secondary effects on tumor behavior. Sildenafil works by inhibiting an enzyme that regulates blood flow, and researchers believe this same mechanism may interfere with how cancer cells move through the body by cutting off their access to cholesterol. Tumors rely on cholesterol to build the cellular structures needed for metastasis, the process by which cancer spreads from its original location to other organs.
The overlap between the Viagra findings and ongoing cholesterol research is notable. A separate set of studies published in 2026 found that statins, cholesterol-lowering drugs, are now recommended for more than 87 million U.S. adults under updated guidelines from the American Heart Association and the American College of Cardiology. The Viagra study found that men who took both sildenafil and statins had the highest survival rates among the groups studied, though researchers stopped short of drawing firm conclusions from that combination given the study's design.
For now, the researchers say clinical trials are the necessary next step. Those trials would need to determine effective dosing, identify which cancer types respond most to sildenafil, and establish whether women would see similar benefits.
