Our pillow (IKEA 365+ Fast) was getting a bit brown so we decided to wash it. With the following result:
It grew a bit, about 5 cm in all directions, and broke apart. We were using 60° C water and 1400 rpm spin speed, I think the latter might have caused it. Maybe we should have tried it at a bit lower speed.
In hindsight I discovered that the IKEA page actually say "Do not wash." :D, the part we read before washing was for the pillow cover. Oh well. Next time I think we'll try it either by hand or at least slower speeds. "Wipe clean with a damp cloth.", which the IKEA page suggests, certainly won't do it.
What's your experience?