Friends worry Rihanna could end up in rehab

Rihanna, 24, tweeted a photo to her 18 million followers of herself hooked up to a hospital drip on Wednesday after a night out partying. Sources said she was suffering from "exhaustion and dehydration."

The "Umbrella" hitmakers friends are worried that her party lifestyle is "spiralling out of control", reported Sun Online.

Earlier Rihanna also tweeted snaps of herself drinking, visiting a strip club and cutting up a mystery substance.

"She's been drinking almost every day and talking about smoking weed a lot. She gets fed up with sitting in her hotel room so she goes out drinking. Everyone is telling her to slow down and think about therapy or rehab," a source said.