COLORADO SPRINGS, Colorado: Maggie Vessey, an American 800-meter runner hoping to qualify for her third trip to the World Athletics Championships, was given a doping warning on Friday (Saturday in Manila) by the US Anti-Doping Agency.

Usada announced that Vessey, who turns 31 on Sunday, tested positive for the prohibited substance Canrenone during a urine test conducted at the IAAF World Challenge in Zagreb, Croatia, last September.

Vessey won the 800m title at the event in 1min 59.61sec but the victory was forfeited because of the positive doping test.

The banned drug was discovered in a prescribed medication that Vessey was taking in a theraputic dose under a doctor’s care.

Because Canrenone is a specified substance, its discovery can result in a reduced sanction, which was the case for Vessey in not facing a competition ban and taking only a warning and the loss of her Zagreb results.

“I took a prescription skincare product that was prescribed to me by my family practitioner, that I did not know contained a diuretic,” Vessey said.

“As soon as I was notified of my positive test, I cooperated with USAda and provided them everything they asked for in order to demonstrate that I made an honest mistake and that the medication did not enhance my performance in any way.

“I have since applied for a Therapeutic Use Exemption for this medication. I share in USAda’s belief in clean sport and look forward to the upcoming track season.”

Vessey was eighth at this year’s US Olympic trials. She reached the 2009 semi-finals in the 800 at the World Championships and was sixth in the final at the 2011 worlds. She is working toward reaching next year’s worlds in Moscow.