Viagra helps women taking antidepressants overcome the sexual dysfunction that can be a side effect of taking the medication, new research says.

Researchers from the University of New Mexico School of Medicine found that women who took the erectile dysfunction drug sildenafil, a.k.a Viagra, had an improvement in sexual function in contrast to women who took a placebo.

The findings are published in the Journal of the American Medical Association.

The researchers said this is the first randomized controlled trial showing that there is a treatment for the sexual dysfunction that women experience as a result of taking antidepressants.

According to information included with the study, sexual dysfunction caused by antidepressant treatment occurs in between 30 and 70 per cent of patients. In fact, sexual dysfunction is a major reason that as many as 70 per cent of patients who are prescribed antidepressants go off the medication in the first few months of treatment.

Dr. H. George Nurnberg and colleagues tested the efficacy of sildenafil versus a placebo to alleviate sexual health problems, such as delayed orgasm or a lack of arousal, in 98 women. The study subjects were taking the most common forms of antidepressants, such as Prozac, Paxil and Zoloft.

Subjects took between 50 and 100 milligrams of either sildenafil or a placebo one to two hours before sexual activity for eight weeks.

The researchers found that 73 per cent of women taking the placebo did not have an improvement in symptoms, while only 28 per cent of women taking sildenafil showed no improvement.

Indeed, the women who took sildenafil showed much greater improvement in sexual function.

"These findings are important not only because women experience major depressive disorder at nearly double the rate of men and because they experience greater resulting sexual dysfunction than men, but also because it establishes that selective phosphodiesterase type 5 inhibitors (such as sildenafil) are effective in both sexes for this purpose," the authors wrote in their study.

The authors noted that treating the side effects of medication will help keep more patients on it. This means the patients will be less likely to have their symptoms worsen, which is a common outcome when patients discontinue medication prematurely because of the side effects.