Hollie Olding, 21, was rushed to hospital when she started coughing up blood after developing a dry cough that she initially believed to be a cold.
However, the otherwise healthy student was shocked by be diagnosed with a pulmonary embolism (blockages in pulmonary arteries in the lungs).
Putney-born Hollie, who was in America on a US scholarship at the time, had been taking the combined oral contraceptive to help manage difficult period pains so they would not affect her performance during matches.
But, while studying at the University of Pittsburgh, she had been flying state-to-state for football games every weekend and noticed she had developed a dry cough in September 2019, as well as night sweats.
While doctors initially thought Hollie had pneumonia as pulmonary embolism is a condition usually associated with the elderly, a scan of her lugs showed blockages in her left and right lungs.
"In October 2019, my team and I were travelling to Florida for two games before returning to Pittsburgh," Hollie explained.
"The cough just wouldn't go but I carried on playing because I was the type to push through the pain.
"Although I played the whole game on Sunday and didn't have any symptoms that bothered me, the next morning I started to cough up blood.
"It was then that I knew something was very wrong and was taken to hospital.
"They told me that my lungs were very damaged and scarred. One of the nurses even said I lit up like a Christmas tree in the scan which was worrying."
Hollie was prescribed blood thinners to help get rid of the blood clots, which left her unable to play football for nine months.
Now back on the pitch, Hollie feels healthier than ever and is speaking out for the first time to encourage other women to listen to their body and know the risks of taking oral contraceptives.
"The doctors figured out straight away that it was due to oestrogen in the combined contraceptive pill I was taking at the time, plus the constant flights I had to make for football," she explained.
"There was no history of clots in my family, so it does seem it was the pill and long periods of being sat down travelling.
"It was really tough. I had gone from being extremely fit and active, to not even being able to make it up the stairs because I would get so out of breath."
She continued: "I was the type of person to push through pain but if I had listened to my body a bit more I'd have caught this earlier.
"I feel like I'm in a fortunate position because I did get a diagnosis and was able to overcome my illness and learn much more about blood clots.
"I would like to spread awareness of the condition especially in female athletes who play football and use contraception."
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