For anyone dealing with long-term dandruff, you know that the commercials for shampoos and treatments usually only cover one-half of the whole experience. While it's true that dry white flakes are problematic and sometimes embarrassing, they're also the least irritating part of handling a scalp that over-produces skin cells. There are, two primary forms of the condition: dry dandruff and oily dandruff, and most people who have the first kind will also experience the second. They are often caused by similar environmental conditions and genetic predisposition but need to be treated separately because of the variation in symptoms and severity.