Demi Lovato's alleged drug dealer claims she ''knew the risks'' of taking drugs.

Brandon Johnson revealed Demi, 26, called him and asked him to come over to her house in the early hours of July 24 and said she ''100 per cent knew what she was taking''.

He told TMZ: ''She texted me at 4am because she's a girl and she wanted to kick it. We hung out.

''She has long hours and stressful days so she wanted to unwind. 100 per cent she knew what she was taking. They're after market pills and they're much stronger. She [Demi] understood fully and it's unfortunate what happened.

''It's a wake-up call for her and it opens my eyes to the dangers. They're fun, but they can be harmful. I'd hate to hurt anybody. I hope she's OK. But for anyone to think there was any misconception on my behalf is absolutely ridiculous. I'm not here to hurt anybody. I care for her very much, she means a lot to me. It's just something that happened. It's unfortunate.''

Brandon also claimed he left Demi's house at 7 or 8am and she was asleep.

The star was later found unconscious by an assistant around 11.30am and revived with Narcan, a medication used to block the effects of opioids, especially in overdose.

He said: ''When I was with her she was fine. When I showed up she was a little drunk, but nothing out of the ordinary. When I left she'd fallen asleep. She'd passed out, but it was already 7am or 8am. I tucked her in.''

Brandon did not reveal the drugs he and Demi - who is currently in rehab - took but it was previously reported to be Oxycodone possibly laced with fentanyl.

And he was arrested just a month before her overdose, when he was charged with driving under the influence (DUI) and being in possession of cocaine.

A few months prior to that he was arrested in North Hollywood, California, after he was allegedly found in possession of narcotics, a fully loaded semi-automatic handgun and $10,000 in his pocket.

Police then searched his home and allegedly found more guns and drugs, but he's yet to be charged.

A source close to the dealer has told TMZ that he's been telling people he was in a ''romantic relationship'' with Demi prior to her overdose and he's adamant he never sold her any drugs.

However, Demi's friends deny their relationship was romantic.