Writing on her Twitter account, the actress revealed that she was taken to hospital following her debut on the ABC show on Tuesday night.
"After premiere. Hospital. I'm okay. Torn muscle in neck to chest. Foxtrot... cruel and sadistic. If only the judges knew," she wrote.
She also posted a photograph of herself wearing a neck brace.
Mazar had received mixed reviews for her salsa with partner Maksim Chmerkovskiy, scoring a total of 16 points. She later received a further six points for her relay foxtrot alongside Natalie Coughlin, Kathy Ireland and Joanna Krupa.
> Click here for our recap of the first results show on Dancing With The Stars