A small study suggests women plagued by menstrual cramps may find relief with vitamin D3, raising hopes that the dietary supplement could one day be an alternative to the painkillers and birth control pills that doctors now recommend.

But the treatment involves a mega-dose of vitamin D - 300,000 IUs - which made one expert add a don’t-try-this-at-home warning.

“This study does suggest (vitamin D) may have a role for menstrual cramps and menstrual pain, but I certainly would not recommend taking doses this high at the present time,” said Dr. JoAnn Manson, who heads the division of preventive medicine at Brigham and Women’s Hospital in Boston.

“The jury is still out,” Manson told Reuters Health. “This is not a definitive trial by any means.”

Menstrual cramping without underlying disease, or primary dysmenorrhea, is a common problem for reproductive-age women.

Although over-the-counter painkillers and oral contraceptives can help quell the pain, the drugs have side effects and so aren’t an ideal option for long-term relief, Manson and a colleague write in a commentary on the new study in the Archives of Internal Medicine.

Vitamin D is known to decrease the production of inflammation-provoking molecules called cytokines, as well as hormone-like substances called prostaglandins - which scientists believe to be a main cause of the distressing cramps.

Studies have suggested prostaglandins may also play a role in conditions like fibromyalgia and joint pain.

So researchers from Italy randomly assigned 40 women with painful periods to either swallow a dose of 300,000 IUs of vitamin D3, or down a shot of inactive liquid.

All of the women had relatively low vitamin D blood levels to begin with, although Manson said they were still higher than what is typically seen in the U.S. And the lower the levels, the more pain women said they experienced.