Chemotherapy is the use of anti-cancer drugs to destroy cancer cells. Each hair on our bodies grows out of a hair follicle. Small blood vessels in the scalp supply the cells of the hair follicles with food and oxygen and carry away waste products. Any chemotherapy drugs in the bloodstream will also be carried to the hair follicles. When blood vessels in the scalp are cooled they become smaller, and so less blood flows through them.
Less chemotherapy reaches the hair follicles, and so the hair is less likely to fall out.
There are two methods that are widely available for scalp cooling. One method uses a hat known as 'cold cap', which is filled with a gel that can be chilled. The hat must be fitted snugly around the head to work properly. The other method of scalp cooling uses a machine similar to an old fashioned hooded hairdryer to circulate cold air around the scalp. Scalp cooling is not suitable for everyone.