Many skin rashes are difficult to tell apart. At first glance, psoriasis and eczema share many similarities but they really are very different conditions even though confusingly, they sometimes appear together. Both psoriasis and eczema are chronic skin diseases but one of the main differences is that eczema can be the result of a condition such as asthma while psoriasis may lead to other conditions such as psoriatic arthritis. Additionally, people with psoriasis are at greater risk of developing heart disease, diabetes and depression.
Psoriasis is a chronic genetic skin disease where skin cells mature much faster than normal (in 3 to 4 days instead of 28 to 30) and instead of falling off, the cells layer on top of each other. In plague psoriasis, the most common form of the five types of psoriasis, the skin develops thickened red raised lesions covered with silvery white scales that flake and may even bleed.
Eczema is a term used to describe a generalized skin rash, usually in response to an allergic reaction. The most frequent type is called atopic dermatitis and is frequently triggered by an irritant such as detergent or an allergic response to a food. The rash is red, can be very itchy and may develop blisters and become “weepy”. Eczema can become thickened and look more like psoriasis if the rash becomes chronic.
Both eczema and psoriasis can occur on the scalp, hands, feet, face or neck. However, one clue that separates eczema and psoriasis is that eczema favors the insides of body parts (flexor surfaces) and is more common inside of the arm and backside of the knee while psoriasis favors outside surfaces (extensor surfaces) such as the backs of the elbows or front of the knees. It can be difficult for even a dermatologist to tell the difference between psoriasis and eczema on the hands but with psoriasis, the nails will show pitting even if the cuticle is not involved.
Early treatment for both eczema and psoriasis can be similar. Both use topical lotions, creams, coal tar and steroids. Oral steroids may be used for more severe cases but only for short periods due to potential serious side effects.