I have used Febreeze and it works to get rid of a mildew smell. You do not have to soak the mattress with it just spray it on and let it dry. If it still smells like mildew repeat. It may take several treatments to get the smell out. However if you notice yourself sneezing or having any allergic reactions to the mildew or the Febreeze you may have to invest in a new matress.