Greasy scalp can also be a linked to the development of skin problems including acne on the face and scalp.  It can be generally categorized into two types which include:
1. Greasy hair from roots to ends with greasy or oily scalp.
2. Greasy scalp and roots with dry hair from below roots to the ends.

Although there are always special circumstances, greasy hair can be caused by the following:
1. Genetic predisposition towards greasy, oily scalp that migrates through the hair.
2. Normal hair without genetic predisposition towards greasiness that is treated with improper hair care products which cause oily/greasy scalp with or without oily/greasy strands.
3. Lack of regular and consistent hair cleansing which results in the build-up of toxins, dirt and other substances resulting in greasy strands. Whether there is a genetic predisposition to greasy hair or not, utilizing improper hair care products and/or methods can lead to greasy strands.

Irregular hair washing, genetically predisposed to greasiness or not, may result in a greasy condition from oil buildup. Even hair that is predisposed to dryness may actually develop greasy roots from lack of washing.