With normal use, down pillows need cleaning but once a year. To protect the outer shell from stains, keep it in a zippered, washable pillow protector sold in linen departments.
If you would like your pillows dry cleaned, find a reputable cleaner who is experienced with down products. Air a dry-cleaned pillow well before sleeping on it.
If you prefer to wash your pillows in a home washer and dryer, do two at a time and follow the instructions in Down comforters.
In time, a down pillow loses the ability to trap air. To revive it, put it in a dryer with a sneaker or tennis ball; set the dryer on Low. Tumble for 10 minutes. If that fails, add more down. Shake the filling to one end of the shell; open part of the opposite seam and insert the neck of another pillow or a bag of down in the opening; add down a bit at a time. Sew the opening with a fine needle and small stitches.