A seven-year-old Scottish girl, who suffers from a rare lung condition, is being kept alive by four doses of Viagra a day.

Natalie Archibald, from Musselburgh, near Edinburgh, was diagnosed with primary pulmonary hypertension after she collapsed on Christmas Day two years ago, the U.K.’s Daily Telegraph reports.

Primary pulmonary hypertension causes abnormally high blood pressure in the arteries of the lungs. As a result, the small arteries of the lungs become narrow, which makes it hard for blood to flow, according to the National Institutes of Health.

The Viagra works by opening the arteries and improving the blood flow.

Natalie’s mother said her daughter’s life has been completely transformed since she started taking the male impotence drug.

"I've never seen her so happy,” Natalie’s mother, Janice, told the Daily Telegraph. “She can run, jump, and skip — all the things her friends do. We have a wheelchair for her if she gets exhausted, but we've never had to use it, and I hope she grows out of it before we need to."

Click here to read more from the Daily Telegraph.