Hair could become discolored due to changes in pigmentation that are part of the natural ageing process. External and environmental factors could also play a role in the change in hair color. Hair that has turned grey or white lacks the pigment which is responsible for the color of hair that is younger. As such it is likely that the hair may take on the color of external substances that it may come in contact with such as water in a swimming pool. Pollutants in the environment can also affect the color of the hair. The hair is very porous and as such pollutants such as dust or smog in the air can be absorbed by the hair. Hair that has melanin also tends to absorb these substances, but the pigmentation makes it less noticeable. When pollutants are absorbed by white or grey hair, it starts to appear dull and yellowish.

Shampoo

Smoking is a common cause of hair turning yellow. The smoke from cigarettes can become absorbed in the hair, leading to discoloration. Just as smoking can cause discoloration of the fingernails and lips, it can also cause the hair to become yellowish. The front of the hair is more likely to become discolored as it is the part that comes in contact with the smoke first. Second hand smoke can also have this effect on the hair. Certain shampoos and other products used for the hair may leave residues after use that can cause a discoloration of the hair. Hairsprays, mousse and gels contain many chemicals that may leave behind traces which can have a discoloration effect on the hair. These products also tend to attract pollutants more easily to the hair. There are also certain medications that can cause the hair to acquire a yellowish tinge. Medications are usually excreted from the skin and scalp pores. As such they may coat the entire hair shaft, thereby giving it a yellowish color.

To prevent hair from turning yellow, you can wash the hair regularly so that there is no buildup of pollutants and product residue. A clarifying shampoo may be used to clean the hair once a week. This must be done especially if you smoke or tend to be exposed to smoke or if you use a lot of hair products. You can also make use of a leave-in conditioner that will mask the porous quality of the hair and prevent contaminants and pollutants from getting absorbed.