As regards hair transplantation by means of natural hair, it is considered permissible, while doing so with artificial hair is considered impermissible. However, this should be restricted to cases of necessity when a person suffers real psychological or social pains.
Sheikh Ahmad Kutty, a senior lecturer and Islamic scholar at the Islamic Institute of Toronto, Ontario, Canada, states:
“Hair transplant by means of natural hair is considered permissible, while doing so with artificial hair is considered impermissible.
Islam prohibits us from unnecessarily interfering or tampering with our bodies. This falls under the forbidden category of mutilation or distortion of Allah’s creation, which has been spoken of as a project Satan is committed to engaging humankind in.
Examples of such tampering and interference are face lift, changing the color of our skin through surgery, likewise, and adding a cluster of false hair to one’s hair. The Prophet (peace and blessings be upon him) “Allah curses women who patch up (their natural) hair with another patch of hair or women who receive such work!”
Having said this, however, it is important to state that Islam is not at all opposed to resorting to treatments or medications in order to enhance Allah’s creation without in any way altering or mutilating it. Hair transplantation of natural hair in such a way that it becomes part of one’s natural hair and grows on one’s scalp and is sustained by it is permissible, for it is not at all different from transplanting a kidney or eyes or a heart. Just as these transplants are considered permissible, to transplant natural hair that would grow and take roots on one’s head is also considered permissible.
Transplanting artificial hair, however, is different. Since it does not become part of one’s natural hair, it is not considered permissible.
It is also permissible to resort to treatments or medications that help natural growth of hair just as we are allowed to take medications in order to enhance our eye sight or physical stamina, etc.”
Excerpted, with slight modifications, from: www.muslims.ca
As for permanent body hair removal, Sheikh Muhammad Salih Al-Munajjid, a renowned Muslim scholar, said,
There is nothing wrong with using any method of removing the hair which we are commanded to remove (such as pubic hair and armpit hair) or the hair which we are permitted to remove (such as hair on the arms or legs), so long as the method used is not harmful – even if it means that the hair will not grow back again.