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What Causes Psoriasis?

Psoriasis turns your skin cells into Type A overachievers: They grow about five times faster than normal skin cells. And your body can't keep up. The old ones pile up instead of sloughing off, making thick, flaky, itchy patches.

Why do these cells go a little haywire? There's more going on under the surface of this skin disease.

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Researchers think something sets off your immune system. The exact reason is a mystery. But it's likely a combination of genetics and triggers.

Your Genes and Your Immune System

Little bits of your DNA, called genes, are instructions for your cells. They control things like your eye and hair color, if you can taste certain things, and other ways your body works. Some genes are only active at certain times.

When you have psoriasis, the genes that control your immune system signals get mixed up. Instead of protecting your body from invaders as it's designed to do, it promotes inflammation and turns skin cells on overdrive.

Scientists have found about 25 genes that are different in people with psoriasis. They think it takes more than one to cause the disease, and they're looking for the main ones.

About 10 in every 100 people have genes that make them more likely to get psoriasis, but only two or three of them actually do.


If you've got the right combination of genes, something can turn psoriasis "on" or start a flare.

Skin injury: A cut, scrape, bug bite, infection, bad sunburn, or even too much scratching can trigger the condition.

Infections: Strep infections, in particular, are linked with guttate psoriasis, which looks like small, red drops. Kids will often have strep throat before their first flare. Earaches, bronchitis, tonsillitis, or a respiratory infection such as a cold, the flu, or pneumonia can also set off your skin problems.

HIV : Psoriasis usually is worse in the beginning stages of the disease, but then it gets better after you start certain treatments.

Medications : Some can make psoriasis worse.

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