Jessica Barrymore
Jessica and Drew share the same father, actor John Drew Barrymore.Facebook

The half-sister of Hollywood actress Drew Barrymore has died in a suspected suicide.

Jessica Barrymore was discovered in the passenger's seat of her car in National City, just north of San Diego on Tuesday. Pills were allegedly found beside her body.

The 47-year-old is the daughter of the 50 First Dates star's father, John Drew Barrymore and his third wife, Nina Wayne. She was set to celebrate her 48th birthday on 31 July.

Hours before her death, Barrymore, who attended the San Diego School of Creative Arts, appeared to hint at her troubles in a cryptic post on Facebook.

"Life doesn't always introduce you to the people you want to meet," she wrote.

"Sometimes, life puts you in touch with the people you need to meet to help you, to hurt you, to guide you, to leave you, to love you, and to gradually strengthen you into the person you were meant to become."

Drew Barrymore, 39, has since released a statement on her sister's tragic death.

"Although I only met her briefly, I wish her and her loved ones as much peace as possible and I'm so incredibly sorry for their loss," she said.