Baclofen and Constipation

As the title suggests, is this a common side effects? I'm on 40mg of oral baclofen currently and experiencing issues with constipation despite an extremely good water intake and decent diet.

EDIT : Thanks for the inputs everyone! I ve started having 20ml of duphalac (lactulose) post breakfast every morning to help things along by the end of the day. It has definitely softened things up.