There is no harm if you are using the hair wax as they are meant to be used. But some people do not use it the right way and do experience the negative effects of it. The biggest mistake is if you do not wash the wax off properly and sleep overnight with it. And if you keep on applying fresh layers of wax without washing the previous one-off, this results in product build on the hair and scalp. This will mix with oil and cause irritation of the scalp and extreme dryness. The dry scalp can then flake off and become dandruff.