The scalp is simply skin; it sweats, secretes sebum (oil) and sheds dead skin cells. You also take your hair and scalp to the same places you take your face and they are exposed to the same pollutants. Daily shampooing is an absolute must if you have a scalp condition, such as dandruff or seborrheic eczema. It is also important if you have fine hair, as this hair texture has more sebaceous glands and therefore becomes oily quickly at the roots. It may not be realistic to shampoo daily if you have very coarse, long or thick hair – and if you must heat-style after you wash, the good of shampooing might be outweighed by this. In all instances, don’t leave more than 3 days between shampoos. Doing so is likely to cause itching and flaking – and a flaky scalp can cause hair loss.