Our Lux Supima cotton fabric needs to be appropriately taken care of. We strongly recommend NOT to wash on high except on rare occasions when absolutely necessary. Washing and drying on high heat settings will significantly reduce the lifespan of your sheets. Drying on high heat settings is particularly hard on sheets. All that said if you need to do a hot wash to kill dust mites, on occasion, it will be ok - just don't do it too often.