Psoriasis is a skin disease that results from a faulty immune system. Instead of only targeting viruses and bacteria, your immune system turns on healthy tissue. It attacks your skin, which speeds up how quickly your skin cells multiply.
Skin usually takes a month to grow and fall off. With psoriasis, the process takes only 3 or 4 days. Skin cells build up, causing thick, red patches called plaques. They’re often covered in white or silvery scales. Although plaques and scales can grow anywhere, they’re most common on your knees, elbows, and scalp.
Psoriasis usually first appears in young adults. No one knows for sure what causes the disease, but genetics play a role. It runs in families. You can’t spread psoriasis from person to person.
Once you have psoriasis, you’ll deal with the condition for the rest of your life. Most of the time, the disease flares up for a few weeks or months, followed by a stretch of fewer or no symptoms. Triggers, such as stress or infections, can set off a flare.
Psoriasis can be unpredictable. In some people, the disease stays mild for years. In others, it worsens quickly. The disease is also more than skin deep. The same inflammation that causes plaques and scales can affect your entire body. This sets the stage for other health issues.