Lovato, 25, reportedly suffered the overdose at her home in Hollywood Hills just before noon and was treated with Narcan, a medication used to reverse the effects of an opioid overdose, before being rushed to an area hospital, TMZ reported.
People is reporting she's "Okay and stable," according to a source.
Lovato has battled substance abuse for years, including several stints in rehab.
Although she celebrated 6 years of sobriety in March, she admitted she relapsed in a song called "Sober," released in June. The single’s release came two months after a photo of her appearing to hold a glass of alcohol at a party surfaced on Instagram.
She performed the song Sunday at a concert with Iggy Azalea at the California Mid-State Fair.
Lovato admitted that she started using drugs at age 17 in her 2012 documentary, "Stay Strong." She entered treatment for the first time at age 18 after a two month bender that included cocaine and adderall. She later relapsed again.
“I was using while I had a sober companion and I went through like 20 sober companions. I was either craving drugs or on drugs. I was not easy to work with,” Lovato said in her documentary. “It’s embarrassing to look back at the person that I was.”
In 2016, she became co-owner of CAST Centers in Los Angeles, the same treatment center she went to when she was 18. She reportedly split from the center and her former life coach and CAST Centers founder, Mike Bayer, in 2018.
Check back for more on this developing story.
Kelcie Willis with the Cox Media Group National Content Desk contributed to this story.