Women who suffer from moderate to severe cramps could find relief in drugs designed to treat erectile dysfunction in men.

Primary dysmenorrhea (PD) is the most common root of female pelvic pain; current treatments are mostly "non-steroidal anti-inflammatory drugs" such as ibuprofen, a Penn State news release reported.

Ibuprofen works in some cases, but fails to relieve many women's pain and is linked to harmful side effects such as kidney damage and ulcers when used regularly.

Sildenafil citrate, better known as Viagra, can help women suffering from PD by dilating blood vessels. Past studies have shown taking the drug orally, but can cause other uncomfortable side effects such as headaches.

A research team observed what happened when the medicine was administered vaginally, and compared the results with a control group.

They looked at 25 female participants between the ages of 18 and 35. The women were asked to rate their pain over the course of four consecutive hours.

The team concluded "Sildenafil citrate when administered vaginally alleviates acute menstrual pain with no reported side effects."

The drug could work because it increases blood flow, but this effect was seen in the control group women as well. The researchers know the drug is effective in alleviating pain, but are not yet sure how it works.  

"If future studies confirm these findings, sildenafil may become a treatment option for patients with PD," said Richard Legro, professor of obstetrics and gynecology and public health sciences, said in the news release. "Since PD is a condition that most women suffer from and seek treatment for at some points in their lives, the quest for new medication is justified."

The team will need to conduct the study on a larger scale in order to confirm their findings. The researchers also hope to learn whether or not the blood interferes with the menstrual cycle itself.