If your pillow is made of “memory foam,” do not wash—because of its unique composition, it may take weeks to dry and mildew can grow inside. Contact the manufacturer for specific instructions.
If your pillow is made of a different kind of foam, it may be hand washed.
Do not machine wash foam pillows. Take to a dry cleaner to get out dirt and oils that have sunk deep inside the foam.
To clean just the surface of the pillow, hand wash in cold water with a gentle detergent like Ivory Snow.
Press gently with towels to remove excess water. Do not put foam pillows in the drier or wring them out. Line dry outside, moving frequently to help keep the shape. Or, lay flat on top of a drying rack.