Healthy looking hair has a smooth, tightly closed cuticle layer that protects the inner cortex from drying out. Hair is composed primarily of proteins (88%). These proteins are of a hard fibrous type known as keratin. Hair comes in a variety of textures from fine to coarse. It can suffer a range of hair damage from fraying, split ends to damage caused by straightening hair with chemical agents or hair irons. There can be hair damage due to heat from blow dryers or curling irons, hair coloring problems, or even scalp problems like over-production of oil from the sebaceous glands. Damaged hair is dry, porous, weak and hard to manage.

There are many causes of hair damage. Hair is especially susceptible to damage when it is wet, so only a wide toothed plastic comb should be used to gently detangle wet hair. A diet low in fruits and vegetables and high in fast food and additives will cause hair to grow more slowly. The growth of the a-keratin shafts that comprise hair depends on good blood circulation in the scalp and healthy, oxygenated blood. Knots, tangles, back-combing and hair elastics can lift the cells of the cuticle layer, which can eventually lead to cortex exposure and hair breakage. Ultraviolet rays from the sun break down some of the natural protein bonds in hair.

The ultraviolet light in direct sunlight affects the cuticle in a similar way to a bleach, and ultimately the keratin protein of the hair breaks down. Cutting hair with blunt scissors or a razor can result in a cut with a long jagged edge which makes the hair more prone to split ends as the cuticle layer can peel away. Heat and Thermal Damage caused by overly hot or overuse of heat styling appliances that dry out hair and cause flyaways. Heat appliances such as blow-dryers or curling irons can over dry the hair. Hair requires a natural level of moisture to remain soft and flexible. Lack of sleep plays a role in altering the hormone balance in the body.

It is lading causes of hairloss. In men, hair loss is attributed to the conversion of testosterone to DHT in the body. Hair colorants lift the cuticle so that the dyes can enter the hair cortex. The process can also dry out the hair. Many chemical also contributed hair loss. Caused by chemical disruption of the hair structure which can leave hair dry and brittle. Bleaching, perming and straightening also break down some protein bonds in hair, weakening its structure. Friction is responsible for more damage than most people realize. Caffeine has the effect of stimulating the central nervous system, and lungs and will stave off fatigue and causes of hair damage.