Britney was caught by her dad / conservator Jamie Spears abusing over-the-counter diet pills mixed with Red Bull before her "Circus" shows, according to Foxnews.com.
“Britney was definitely trying to get high by taking too many diet pills and energy drinks,” said a source.
“Jamie thinks the combination of the two is making her whacked-out and, causing her to lash out in weird angry rampages.”
“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."
Be wary of those security guards / tour staff!