Ruling on a woman using hair extensions to beautify herself for her husband
27-8-2015 | IslamWeb
Question:
I am about to get married, but I have a problem that makes me worry. My hair is very thin; can I wear removable hair extensions for the purpose of beautification for my husband?
Answer:
All perfect praise be to Allaah, the Lord of the worlds. I testify that there is none worthy of worship except Allaah and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.
If your hair is so thin that others see it as a physical defect, then you should inform your husband of that so as to avoid deceit and also to avoid any potential problems after marriage because of that defect. The Prophet, sallallaahu ‘alayhi wa sallam, said: "Whoever cheats is not one of us."
As for wearing hair extensions, it is strictly prohibited. The Messenger of Allaah, sallallaahu ‘alayhi wa sallam, said: "Allaah has cursed the woman who lengthens (her or someone else's) hair artificially or gets it lengthened, and also a woman who tattoos (herself or someone else) or gets tattooed." [Al-Bukhari]
The Hadeeth refers to the woman who artificially lengthens her hair and the one who attaches extensions to the hair of another woman.
Women are forbidden to wear hair extensions in general whether the husband knows about it or not and whether he likes it or not. ‘Aa’ishah 
reported that a woman from the Ansar married off her daughter, and she lost her hair because of illness. She came to the Prophet, sallallaahu ‘alayhi wa sallam, and said, "Her husband desires her; may I lengthen her hair by using hair extensions." Thereupon, the Messenger of Allaah, sallallaahu ‘alayhi wa sallam, said: "The woman who attaches (hair to her hair) has been cursed." [Al-Bukhari and Muslim]
The version of the Hadeeth narrated by Imaam Al-Bukhari reads, "Her husband asked me to extend her hair." The Prophet, sallallaahu ‘alayhi wa sallam, said: "No (do not do that), for a woman who attaches (hair to her own) has been cursed." [Al-Bukhari]
Imaam An-Nawawi 
said:
These Ahaadeeth explicitly underline the prohibition of artificially lengthening one's hair and the fact that women who attach hair extensions to their hair or to others are cursed. This is the preponderant opinion that we adopt ... This hadeeth highlights that artificially lengthening one's hair is forbidden whether the woman has an excuse, is a newlywed, or in any other situation. [Sharh of Muslim's Saheeh]
If a woman lost her hair due to an illness, then it is impermissible for her to use hair extensions or wear wigs because this is a kind of artificial lengthening of the hair. Instead, she should consult a specialist. Indeed, Allaah, the Exalted, has never created an illness without creating its cure, which is known to some people and unknown to others.
Allaah Knows best.