Psoriasis is a chronic disease which develops when a person’s immune system sends faulty signals that tell skin cells to grow too quickly. New skin cells form in days rather than weeks. The body does not shed these excess skin cells. The skin cells pile up on the surface of the skin, causing patches of psoriasis to appear. Psoriasis may look contagious, but it’s not. You cannot get psoriasis from touching someone who has it. To get psoriasis, a person must inherit the genes that cause it.
Eczema is a general term. Dermatologists use it to describe skin conditions that can cause the skin to swell and discolor. The skin is often dry and itchy. Sometimes blisters form. The most common type of eczema is atopic dermatitis. When people say “eczema,” this is often what they mean — but not always. If your dermatologist diagnoses you with eczema, your dermatologist may use the word “dermatitis.” The words “eczema” and “dermatitis” often mean the same thing.
Rosacea is a common skin disease. It often begins with a tendency to blush or flush more easily than other people. The redness can slowly spread beyond the nose and cheeks to the forehead and chin. Even the ears, chest, and back can be red all the time.
Rosacea can cause more than redness. There are so many signs and symptoms that rosacea has four subtypes:
- Erythematotelangiectatic rosacea: Redness, flushing, visible blood vessels.
- Papulopustular rosacea: Redness, swelling, and acne-like breakouts.
- Phymatous rosacea: Skin thickens and has a bumpy texture.
- Ocular rosacea: Eyes red and irritated, eyelids can be swollen, and person may have what looks like a sty.
With time, people who have rosacea often see permanent redness in the center of their face.
Hives are welts on the skin that often itch. These welts can appear on any part of the skin. Hives vary in size from as small as a pen tip to as large as a dinner plate. They may connect to form even larger welts.
A hive often goes away in 24 hours or less. New hives may appear as old ones fade, so hives may last for a few days or longer. A bout of hives usually lasts less than 6 weeks. These hives are called acute hives. If hives last more than 6 weeks, they are called chronic hives.
Acute hives often result from an allergy, but they can have many other causes.
Resources: American Academy of Dermatology
Who Psoriasis Affects and What Causes It
Psoriasis Treatment Options
Psoriasis Case Example
Psoriasis & Depression