Kelly Osbourne alleges that rehab was a "lesson in how to improve as a drug addict."

Kelly Osbourne has openly discussed her past struggles with substance abuse, which started during her teenage years.

Ozzy Osbourne's daughter's first rehab stint taught her how to acquire drugs rather than helped her achieve sobriety goals.

"My first rehab experience was similar to attending a university for improving my skills as a drug addict," Osbourne stated on "TMZ Investigates: Matthew Perry & The Secret Celebrity Drug Ring."

"I had learned numerous tricks and ideas from my fellow addicts that I never considered before, all of which were in the group."

She added, "I've also seen individuals threaten to depart until they received what they desired, whether it was Ambien for slumber or Valium for anxiety - they ultimately obtained it.

"First rehab I went to was like university on how to be a better drug addict." — Kelly Osbourne

Osbourne's addiction journey started at the age of 13 when she received opiod medication after a tonsil removal surgery.

When her family became famous on "The Osbournes," her addiction problems worsened. At age 19, she tried rehab for the first time.

Over the years, Osbourne, 39, tried rehab seven times. She recalled leaving meetings and seeing "body brokers" outside, waiting to lure vulnerable addicts back into the addiction cycle.

She stated that they would sit outside of AA meetings in search of weak and vulnerable individuals, whom they would encourage to relapse, in order to pick them up again.

"I'd learned so many tricks, so many things that I never even thought of from my fellow addicts that were in there." — Kelly Osbourne

"I solemnly swear that it is true, and it is heartbreaking."

In 2021, the host of "Fashion Police" experienced a relapse after maintaining sobriety for four years.

"Although it's difficult for me to discuss, I have always pledged to be truthful with you about my journey and current status. I recently relapsed, but I am now back on track."

During an appearance on "Red Table Talk," she revealed that Vicodin was her gateway drug for addiction.

"I went from hearing every voice in my head criticize me, telling me I was fat, ugly, not good enough, unliked, and undeserving, to having all voices suddenly silenced, leaving me feeling like life had given me a hug," she said.

Once the opioids were no longer effective, she moved on to heroin.

"I wondered why I was so confident in everything, and then I rapidly progressed from Vicodin to Percocet, then to heroin because it was more affordable," she stated.

Since maintaining her sobriety, Osbourne welcomed a son with Slipknot frontman Sid Wilson in May 2022.

"TMZ Exposes: Matthew Perry & the Elite Celebrity Drug Network" airs on FOX and Hulu starting Monday, September 16 at 9 p.m. ET.