I have been wearing the hijab for a few years and have started to experience heavy hair loss for months now. I consulted a physician who advised me to remove my hijab as a precaution to protect my hair from falling out. I want to take my hijab off but I am scared. What is the ruling?

In Islam, a Muslim woman is to cover her entire body except for her face and hands. It is permissible for her to wear any type of attire she wishes provided she abides by the prescribed conditions for hijab and her garments do not lead to tempting men or arousing unlawful desires.
As for your problem, you have to find out the actual cause of your hair loss. Some of the things that cause hair to fall are stress, poor nutrition, medications, illness, and hormonal problems. The diagnosis will determine the proper treatment. However, if you continue to experience hair loss, the legal maxim states, "Do not harm and do not reciprocate harm." This means that you can use light fabric for hijab to avoid harm. Do not use tight caps and do not wrap the headscarf too tight; you may tie it a little loosely to protect your scalp from harm.

The ruling
Based on the above and in reference to the question, it is impermissible to remove your hijab. The only permissible case is when the hijab poses a serious threat to a woman’s health, which may lead to grave consequences. When the necessity ends and the harm is removed, a woman must don her hijab once again and abide by the full Islamic attire.
And God Almighty knows best.