Wa `alaykum As-Salamu wa Rahmatullahi wa Barakatuh

You are allowed to cut your hair or clip your nails and perform all hygienic practices while fasting. None of these activities would nullify your fast. We are not allowed to make up the rules of religion based on hearsay or customs of people without any basis in the authentic teachings of the Quran and the precedents of the Prophet, peace be upon him.

As Muslims, we ought to trust that the Prophet, peace be upon him, has communicated the message. If it had been necessary for us to abstain from such normal activities, then he would have said so clearly. Since there is nothing in the sources to indicate that, we ought to dismiss such beliefs and practices as innovations. The Prophet, peace be upon him, said, “Whoever innovates anything in this religion without our sanction, it must be rejected.” (Ibn Hibban)

It is an excellent practice to do such hygienic chores once a week; if you cannot do so, then at least once in every forty days.

Almighty Allah knows best.