Former American Idol favourite Nikki McKibbin has died, aged 42.

The singer, who came in third on the first season of Idol in 2002, passed away on Sunday morning after reportedly suffering a brain aneurysm.

McKibbin's life was plagued by substance abuse issues and she appeared on reality TV show Celebrity Rehab in 2008 and spin-off Sober House.

She also featured on the TV shows Fear Factor and Battle of the Network Reality Stars.

The Texas-born singer leaves behind husband Craig Sadler, who she wed in 2007, and a teenage son, Tristen Langley, who auditioned for Idol in 2014.

Justin Guarini, the runner-up to Kelly Clarkson in the finale of the first season of Idol, has paid his respects to his fellow alum, stating: "@realnikkimckibbin was a fiery, funny lady who could sing the Hell out of a rock song with the same kind of ease and command she lovingly used to cut you with her twangy Southern wit. ?Even in our 20's when we were on American Idol together I could tell that she'd had a challenging life, and that not that many people had been kind to her along the way...

"I'll never forget the day that her idol, Stevie Nicks, sent her flowers with a card that said 'You are the Gypsy that I was...' Nikki was on cloud nine and the joy and excitement that radiated from her was infectious. After the kind of emotional beating she took at the hands of the masses, she deserved to feel good about herself, even for a little while.

"Rest well, 'Gypsy'... and thank you for the laughter, merciless teasing, strength, vulnerability, love and friendship you showed me during our time together in the spotlight."

A spokesman for Idol adds: "Nikki McKibbin was an incredible talent and we are deeply saddened by the news of her passing. She was part of our American Idol family and will be truly missed. Our hearts and prayers go out to her family and friends during this difficult time."