Is my prayer permissible if my hair is oiled with foul-smelling oils to treat hair loss?

If the oily substances used for hair are free from impurity, there is no harm in praying with them merely because of the smell, as smell does not invalidate prayer. However, the worshiper should be in the most complete and best appearance when supplicating to his Lord, because he stands before the King of kings, Glorified be He, and He is most deserving of beauty and majesty.