Dandruff can be caused by abnormal growth of certain yeasts on the scalp and shouldn't be confused with just having a very dry scalp (low sebum production can also cause flaking). A dry scalp can easily be treated by applying jojoba oil the night before washing, an oil that is much like the natural sebum. On the other hand, real dandruff is very hard to treat and may unfortunately never completely go away.. I would recommend to see a doctor or dermatologist who can prescribe a medicinal dandruff shampoo. H&S may work, but remember that it is a shampoo with sodium lauryl sulfate in it, a detergent that is very drying to the hair.