A team of researchers have claimed that women suffering from moderate to severe menstrual cramps may find relief in a class of erectile dysfunction drugs.

Primary dysmenorrhea, also called PD, is the most common cause of pelvic pain in women.

Sildenafil citrate, sold under the brand name Viagra, may help with pelvic pain because it can lead to dilation of the blood vessels.

The researchers looked at administering sildenafil citrate vaginally, which had not yet been tried, to treat PD.

They compared pain relief from use of sildenafil vaginally with that of a placebo.

Penn State College of Medicine researchers worked with researchers at Nova Gradiska General Hospital in Croatia.

They recruited women 18 to 35 years old who suffered from moderate to severe PD. Of the 29 women screened for the study, 25 were randomized to receive either sildenafil or a placebo drug.

Patients rated their pain over four consecutive hours. Sildenafil citrate administered vaginally alleviates acute menstrual pain with no reported side effects.

Researchers hypothesized that the drug would alleviate pain, which it does, but also that is does so by increasing blood flow. However, because uterine blood flow increased from both sildenafil and the placebo, the reason it alleviates pain is not yet known.

The study has been published in journal Human Reproduction.