A COUPLE injected their three young children with heroin, telling them it was “feel-good medicine” to help them sleep, police in the US said.

Ashlee Hutt, 24, and Leroy McIver, 25, allegedly drugged their son, six, and daughters, four and two, in their filthy Washington home filled with rat droppings and used needles.

Child Protective Services (CPS) launched an investigation in November last year after someone in the house claimed they saw the children with the drug, Kiro7 reported.

According to a probable cause affidavit, the six-year-old told investigators “his mum and dad give him and his sisters the ‘feel-good medicine’” which “he described as a white powder which was mixed with water”. He said his parents “used a needle to inject the ‘feel-good medicine’ into him and his sisters.”

Charges: Ashlee Hutt, 24, injected heroin into her children ages 2, 4, & 6. They reportedly called it "feel good medicine" pic.twitter.com/00zyAqeVOm — Kevin McCarty (@KevinKIRO7) October 31, 2016

“Some of the statements they [the children] made were very disturbing about how they would get sleeping juice to go to sleep and it was injected into them by needle,” Pierce County Sheriff’s Department spokesman Detective Ed Troyer said, according to Kiro7.

Puncture marks and bruising consistent with needle injections were also found on the children’s bodies. Testing showed traces of low levels of what was believed to be heroin in two of the children.

The News Tribune reported Hutt and McIver admitted to CPS officers they were heroin addicts. Their children were placed into foster care in November 2015.

They face three counts each of unlawful delivery of a controlled substance to a minor, second-degree criminal mistreatment and second-degree child assault, and are being held in lieu of $US100,000 bail.