A "Loofah" [sic.] is a bit much for psoriasis. A good gentle exfoliator for other bits is one of Lidl's white microfibre cleaning cloths. They make wondeful wash cloths, soft to touch, but effective. Best thing, they're cheap. In addition, if you keep wringing them out, they are so absorbent that you can dry yourself completely with one. they discolour eventually and can be demoted to household cleaning, where they will wipe grease off the kitchen cupboards with just warm water and suds.