Aaron Carter's Autopsy Reveals Cause of Death, Xanax and Huffing Led to Drowning

Aaron Carter took prescription pills and huffed before his death, according to the autopsy results ... TMZ has learned.

The Los Angeles County Medical Examiner says its findings show Aaron drowned in the bathtub of his Lancaster home, but he took alprazolam -- generic Xanax -- and inhaled compressed difluoroethane ... which is the propellant used in cans of compressed air.

The report says he became "incapacitated while in the bathtub due to the effects" of the drugs and the huffing ... and, ultimately, he slipped under the water and drowned. Aaron's death is officially ruled accidental.

TMZ broke the story -- Aaron was found dead last November. Aaron's family claimed the coroner had told them there was no water found in his lungs, and they believed he had died of a drug overdose.

According to the autopsy report, there were multiple cans of Surf Onn compressed air found in A bathroom and bedroom. Additionally, authorities found several prescription bottles in the home.

Several clothing items were found near the bathtub -- including a beanie, sweatshirt and pants. A nozzle tip to one of the compressed air cans was found in a front pocket of that sweatshirt.

Aaron's fiancée, Melanie Martin, told us she thought drugs were what killed him -- you'll recall, he had a serious substance abuse problem in the years leading up to his death. As we previously reported, cops found cans of compressed air and prescription pills in Aaron's bedroom and bathroom.

Melanie told us there was a text exchange on Aaron's phone, saying he owed someone $800 for an unknown substance ... submitting the exchange to authorities for further investigation.

His mom, Jane, revealed a series of photos in early March from Aaron's bathroom the day he was found, believing it wasn't an overdose -- instead, calling it a crime scene and speculating that her son may have been a victim of foul play.

Jane said she had support from Aaron's family and friends to put the pics out there, wanting to bring the spotlight back to the case.

We covered it all in the recent episode of The TMZ Podcast, available on all podcast platforms!