What Is Psoriasis?

It often starts with a patch that refuses to behave like ordinary dry skin. Moisturiser helps for a day, then the roughness is back — thicker, redder, with a silvery surface that flakes. That stubborn patch is the classic calling card of psoriasis, a long-term skin condition driven by the immune system. The video above, "Psoriasis" (about four minutes), is a good place to start: in it, a dermatologist explains how the condition is recognised and treated, and the challenging effects it can have on a person's day-to-day life.

Step one: the skin's production line speeds up

Healthy skin renews itself steadily, with new cells rising to the surface over several weeks. In psoriasis, immune signals tell the skin to hurry. Cells are produced far too quickly and reach the surface in days, piling up faster than they can shed — and that pile-up is the raised, scaly plaque you can see and feel. Psoriasis isn't an infection and it isn't caused by poor hygiene; it's the same kind of immune mix-up seen in other autoimmune conditions, such as lupus, where the body's defences act against its own tissue.

Step two: learning to recognise the pattern

Plaques favour certain places — elbows, knees, the scalp, and the lower back are common — though they can appear almost anywhere. They tend to be well-defined, meaning you can see fairly clearly where the plaque ends and normal skin begins. Nails can join in, becoming pitted, thickened, or lifted. Itch varies a lot: some people barely notice it, others find it the hardest part. And like many immune-driven conditions, psoriasis moves in flares — a patch worsens for a while, settles, then stirs again, sometimes after an infection, a period of stress, or a knock or scrape to the skin.

Step three: how a doctor confirms it

Most of the time, diagnosis is a looking exercise. A doctor — often a dermatologist — examines the plaques and nails, asks where they appear and how they behave over time, and checks whether similar problems run in the family. A handheld magnifier that lights the skin's surface helps reveal detail that the naked eye misses. Blood tests aren't usually what makes the diagnosis; only occasionally is a tiny skin sample taken, mainly to rule out look-alikes such as eczema or a fungal infection.

Step four: treatment climbs a ladder

There's no permanent cure, but there is a well-worn ladder, and most people start on the lower rungs. For limited areas, that means treatments applied directly to the skin, alongside generous moisturising to soften scale. If plaques are widespread or stubborn, light-based treatment under medical supervision is a next step. More extensive or hard-to-control disease can call for medicines that act throughout the body and calm the immune signals driving the speed-up. A second video on this site, "Psoriasis Treatment" (just under three minutes), surveys those options. One thing worth saying out loud at any step: mention joint aches, swelling, or morning stiffness to your doctor, because psoriasis can travel with an inflammatory arthritis, and joints do best when that's caught early.

MedicalVideos.com has published trusted medical videos since 2007. The site was founded by Dr. Mohamed Ibrahim, MD, PhD — physician and researcher.

Educational only — this article is general information about psoriasis, not medical advice and not a diagnosis. If you have a persistent rash or thickened, flaking patches that do not settle, contact a clinician for assessment.

Frequently Asked Questions

Is psoriasis contagious?
No. Psoriasis is an immune-driven skin condition, not an infection. You cannot catch it from another person or pass it on by touch.

What sets off a psoriasis flare?
Flares can follow infections, periods of stress, injury to the skin such as a scrape or sunburn, and cold, dry weather. The triggers differ from person to person.

Can psoriasis affect joints as well as skin?
Yes — some people with psoriasis develop an inflammatory arthritis linked to the condition, causing joint pain, swelling, and stiffness. New joint symptoms are worth reporting to your doctor promptly.

Does psoriasis ever go away for good?
It is a long-term condition that tends to flare and settle rather than disappear permanently. Treatment aims to calm the skin, lengthen the quiet stretches, and keep flares as mild as possible.