Panettiere says, "I chopped it all off and my hair started falling out because I dyed it red and then tried to dye it back blonde.
"I like drastic changes... It has taken a lot of nursing back."
And she admits she met boyfriend Wladimir Klitschko's family for the first time during her hair crisis.
She tells Ellen DeGeneres, "I was like, 'Look, I really don't look like this all the time, I swear... Just don't judge me.'"