Psoriasis is a skin condition that causes ... One study showed that lotion with 1% coal tar worked better than lotion with 5% coal tar. Ask a dermatologist what strength would be best for you.

A 40-year-old Hispanic man presented for treatment of dermatitis on his elbows and knees that had been evident for 5 years ... to use a tar shampoo containing 4% neutar solubilized coal tar ...