New Castor NF Cream is used to reduce swelling, itching, and redness caused by certain skin infections (psoriasis, dermatitis, eczema, allergies, rash) caused by bacteria and fungus. Fungal infection is a skin disease in which a fungus attacks the tissue and causes infection. Fungal infections may be contagious (spread from one person to another). A bacterial infection is a condition in which harmful bacteria grow in the body and cause infection. It can infect any part of the body and multiply very quickly.