What a Muslim may recite if he/she is going to use the toilet?

Praise be to Allah, the Lord of the Worlds; and blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.
The one who wants to answer the call of nature should say: 'O Allah, I seek refuge with you from all evil and evil doers'. Narrated Anas bin Malik: The Prophet before entering the toilet would say "O Allah, I seek refuge with you from all evil and evil doers".

Allah Knows best.