Hair falling out of the Head of the Muhrim
Question :
What should the woman in Ihram do if some hair falls out of her head against her will?
Answer:
If hair falls out of the head of the person in Ihram - whether it is a male or female - when he wipes it during Wudhu' or when he washes it, that does not harm him. Likewise, if hair falls out of the beard of a man or his moustache or something of his nails falls off, that does not harm him if he did not do that intentionally. The only thing that is prohibited is that the Muhrim intentionally cuts some of his hair or his nails while he is in Ihram. Likewise, the woman may not intentionally cut anything (from her hair or nails). In reference to something falling off without the person intending that, then these are dead hairs that fall out during movement, and their falling out does no harm. And Allâh knows best.
Source:
The Permanent Committee
Fatawa Islamiyah, Vol. 4 Page 138