One who takes the nazirite vow becomes subject to a number of restrictions, including “Ta’ar Lo Yabo Al Rosho” – literally, “a razor shall not pass over his head” (Bamidbar 6:5), meaning, he may not cut his hair. A Nazir may not remove a hair from his head with a razor, with scissors, or even by pulling them out with his hand. The Rambam writes that a Nazir violates this prohibition only if he removes the entirety of the hair, or most of the hair. If he cut the hair but left enough of the hair that it can be folded, he is not liable for a Torah violation. Applying chemicals that causes hair to fall does not violate this prohibition, but it does violate a separate affirmative command requiring a Nazir to allow his hair to grow (“Gadel Pera Se’ar Rosho” – Bamidbar 6:5). Therefore, a Nazir who removes hair in this fashion is not liable to Malkut, because he transgressed only an affirmative command, and not a prohibition. A Nazir violates a Torah command for every hair that he removes. Thus, if he is given a separate warning before removing each hair, then he is liable for a separate set of Malkut for each hair that he removes. The Sefer Ha’hinuch writes that a Nazir is allowed to scratch his head, because this is not certain to cause hair to fall from the scalp. Combing the hair, however, is forbidden, because this will inevitably cause hair to fall. Although the Nazir does not intend to remove hair when he combs, nevertheless, since this is inevitable to occur, it is forbidden (a Halacha known as “Pesik Resheh”). This is the source of the Halacha that forbids combing one’s hair on Shabbat. Removing hair from the head is forbidden on Shabbat, and thus one may not comb his hair, as this will inevitably result in the removal of hair, irrespective of the fact that this occurs unintentionally. The Mishna Berura goes so far as to say that one who attends the synagogue with combed hair has the status of a “Mehalel Shabbat Be’farhesya” (public Shabbat violator), as he appears in public with his hair groomed in a way that must have entailed an act of Shabbat desecration. After the Nazir completes his period of Nezirut, he must remove all the hair on his head. The Sages understood that even if only two hairs remain, he has not fulfilled his obligation; he must remove all his hair until no more than a single hair remains. If a Nazir violates his vow by cutting his hair, then the days he had observed are considered void, and he must begin anew the period of Nezirut to which he had committed. However, this Halacha – called “Setira” – applies only if the Nazir cut the majority of his hair. Although he violates a Torah prohibition with the removal of each strand of hair, as mentioned above, nevertheless, the requirement to begin his period of Nezirut anew does not take effect unless he cuts the majority of his hair. This prohibition applies to both men and women – as both can take the nazirite oath – and in all times and places. Even nowadays, if a person declares himself a Nazir, he is bound by all the restrictions that apply to a Nazir, including the prohibition against haircutting.