Nah, you can use anti-dandruff shampoo with dread extensions! It helps to medicate and moisturize your scalp and it won't affect the dreads at all. The only reason I usually advise against it is because Dandruff shampoos are notorious for pulling out hair color and many people who wear dread extensions typically have colored hair. But if you don't dye your hair, you've got nothing to worry about. ;)