All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
It is prohibited for a Muhrim (the person who is in the state of Ihram) to cut or shave his/her hair of body. Allah Says (what means): {… And do not shave your heads until the sacrificial animal has reached its place of slaughter.} [Quran 2: 196]
Ka'b ibn ‘Ujrah narrated: “The Prophet came to me at the time of Al-Hudaybiyyah Pledge while lice were falling on my face. He said, “Are the lice of your head troubling you?” I said, “Yes”. He said, “Shave your head and fast for three days, or feed six poor persons, or slaughter a sheep as sacrifice.” [Al-Bukhari and Muslim]
There is a consensus of Muslim scholars that it is prohibited for a Muhrim to cut or shave his/her hair with the exception of any valid excuse [Al-Mughni by Ibn Qudamah]
However, if a Muhrim has any valid excuse such as sickness, lice in his/her head, etc. and he suffers if he keeps his/her hair, then in such a case it is permitted to remove the hair. Allah Says (what means): {And whoever among you is ill or has an ailment of the head [making shaving necessary must offer] a ransom of fasting [three days] or charity or sacrifice.} [Quran 2:196]
Know that the rulings pertaining to hair of body are similar to the rulings of hair of head. So, if you suffer physically from the facial hair then it is permitted to remove them and pay the expiation. The expiation is slaughtering a sheep as sacrifice, or fasting three days, or feeding six poor people; every poor person should be given half a Saa'; i.e., 1240 grams.
If one removes his/her hair many times and yet did not pay expiation, then he/she should pay only one expiation. If he pays expiation after removing his/her hair, and again removes his/her hair, then he/she should repeat the expiation as per the view of the Schools of jurisprudence of Imam Ahmad and Ash-Shaafi'i.
Allah knows best.