I wash the cover and the entire boppy. The boppy I was on the gentle cyle and dry on low. It keeps it's shape well, for I have washed it at least six times.
I have washed both. For the pillow itself I wash it on gentle cycle and dry on low or air dry. The tag also said to put a clean tennis ball in the dryer to help break down the lumps that can form after washing. I did not noticed any lumps, but I still tossed in a tennis ball. I had no issues.
Re: Washing a Boppy
I wash mine all the time. I don't have a cover,so I just put the whole thing in the washing machine, then in the dryer.
It looks a bit wobbly at first, but it takes it's shape back just fine.