Britney Spears reportedly popped diet pills with energy drinks to get high before a performance on her Circus tour.
The pop princess, 26, was allegedly caught by her conservator-father Jamie when she was trying to guzzle down Red Bull with the pills.
"Britney was definitely trying to get high by taking too many diet pills and energy drinks," Fox News quoted a source as having told gossip site Betty Confidential.
"Jamie thinks the combination of the two is making her whacked-out and, causing her to lash out in weird angry rampages," the source added.
The insider also said: "Britney uses green-tea supplements, [Lab 88's herbal ephedra-free] Metabo Speed XXX, Dexatrim and apple cider vinegar to control her weight and energy levels. She also pours those 5-Hour energy drinks into her Red Bulls."