Start with the care label on the product, because it gives the safest instructions for this specific model. For a soft cervical collar of this type, a common approach is hand washing in lukewarm water with a mild detergent. Clean the fabric cover and padding gently, rinse thoroughly, and let everything air dry completely before the next use. If the cover is removable, check whether the instructions allow washing it separately; if not, clean the collar as a whole without soaking the padding longer than needed.
Avoid hot water, bleach, strong detergents, and machine drying. Heat and aggressive cleaning can deform the padding or damage the cover, which changes how the collar sits on the neck. Do not wring the collar forcefully; reshape it by hand while it dries so the padding keeps its even height.
Because the collar contacts the skin directly, regular cleaning makes sense during daily use. Once a week is a reasonable habit, and more often if the child sweats or the collar becomes visibly dirty. Before each use, check the cover for fraying or tears and the padding for compressed spots. A collar with damaged padding will not hold the neck in a steady position as intended, and it may be time to replace the product.