Rumer, the eldest of Demi Moore's three daughters by her ex Bruce Willis, was seen visiting the troubled actress in hospital.
She looked visibly distressed outside the clinic in LA where the brunette beauty has sought treatment for exhaustion.
Since the shock break up of the Margin Call star's union with Ashton Kutcher mum and daughter have become closer than ever.
On several occasions, Demi has been seen out in Hollywood with the 23-year-old and her friends.
Now, with her estranged husband partying in Brazil with supermodels pals like Alessandra Ambrosio and Bruce focusing his attention on his own pregnant wife Emma, it has been left to Rumer to step in.
A source close to the family told a US website that Rumer is "devastated".
"She worries day and night about her mother and has been watching her mom fall apart."