Warning: This story may be distressing to some readers.

A Perth mother has been charged with trying to kill her chronically ill baby by pouring bleach down his feeding tubes.

Baby William was born 14 weeks premature and suffers from a rare disease and requires constant care.

Baby William was born 14 weeks premature and requires regular care for an ongoing illness. (9news)

Brooke Evelyn Lucas is accused of pouring bleach down her sick son's feeding tube. (9news)

Police allege the 13-month-old's mother poured the cleaning chemical into his feeding tubes on December 29, just five days after he was discharged from Perth Children's hospital.

The child was rushed to Perth Children's hospital.

Detectives from the Child Abuse Squad arrested Brooke Evelyn Lucas yesterday and charged her with intent unlawfully to kill committed an act or omission likely to endanger life.

The 26-year-old faced Perth Magistrates court today.

She was inconsolable when she appeared before the judge today.

William has spent most of his life in and out of hospital, his mother describing it as a "Christmas miracle that he would be home for Christmas".

Brooke Evelyn Lucas allegedly posted on social media about how excited she was her ill son would be home in time for Christmas. (9news)

"I am in tears after he was so sick Friday and Saturday that he needed to be admitted into hospital. Doctors think he had bronchitis. But has bounced back better than ever," she wrote on Facebook on Christmas Eve.

Five days later he was rushed back to hospital after she allegedly fed him bleach.

9News understands doctors managed to treat the critically ill child before there was any serious damage to his body.