In the name of Allah, the most Beneficent, the most Merciful.
It is mustuhub and desirable to cover ones head when entering the toilet. It will be considered against etiquette to enter the toilet without covering the head. (Raddul Muhtar p.559 v.1 & Bahrur Raaiq p.256 v.1)
Only Allah Knows Best
Mohammed Tosir Miah
Darul Ifta Birmingham