Psoriasis is a skin condition where your immune system causes skin cells to build up faster than normal, creating thick, scaly patches

Psoriasis happens when your immune system mistakenly attacks skin cells, telling them to multiply much faster than they should. Normally, skin cells replace themselves every 28 to 30 days. With psoriasis, that cycle speeds up to just 3 to 7 days. Your body can't shed the old cells fast enough, so they pile up into raised, inflamed patches covered with silvery or white scales. These patches are usually red or purple underneath and can itch or burn.

The condition is not contagious. You cannot catch it from someone else or pass it to another person through touch. Psoriasis is chronic, meaning it lasts a long time, but it comes and goes—you might have clear skin for months and then have a flare-up triggered by stress, infection, injury, or certain medications.

Key Takeaways

  • Psoriasis occurs when your immune system causes skin cells to reproduce too quickly, creating thick, scaly patches that may itch or burn.
  • The condition is not contagious and cannot spread from person to person through contact.
  • Psoriasis is chronic but cyclical—patches may clear up for weeks or months, then return during a flare-up.
  • Flare-ups are often triggered by stress, infections, skin injuries, cold weather, or certain medications like beta-blockers.
  • Different types of psoriasis affect different parts of the body, and severity ranges from a few small patches to coverage of large areas of skin.

The five main types of psoriasis and where they appear

Plaque psoriasis is the most common form, accounting for about 80 to 90 percent of cases. It creates thick, raised patches with silvery scales, usually on the elbows, knees, scalp, lower back, and nails.

Guttate psoriasis shows up as small, drop-shaped spots, often after a strep throat infection. These spots typically appear on the trunk and limbs and may clear on their own or develop into plaque psoriasis over time.

Inverse psoriasis appears in skin folds—armpits, groin, under the breasts, or between buttocks. These patches are usually smooth and red without the typical silvery scaling, and they worsen with sweat and friction.

Pustular psoriasis causes pus-filled bumps surrounded by red skin. It can appear in small areas or cover large parts of the body and is less common than plaque or guttate forms.

Erythrodermic psoriasis is rare and severe, causing widespread redness and scaling that covers most of the body. This type requires medical attention because it can affect temperature regulation and fluid balance.

What triggers a psoriasis flare-up

Stress is one of the most common triggers. When your body is under emotional or physical stress, your immune system can become overactive, setting off a flare. This creates a difficult cycle: psoriasis causes stress, which triggers more psoriasis.

Infections, especially strep throat and upper respiratory infections, frequently precede flare-ups by one to two weeks. Skin injuries also trigger the condition—cuts, scrapes, sunburns, or even tattoos can cause psoriasis to appear at the injury site, a response called the Koebner phenomenon.

Cold, dry weather worsens psoriasis for many people because low humidity dries out the skin. Certain medications can also trigger flares, including beta-blockers (used for high blood pressure), lithium (used for bipolar disorder), and antimalarial drugs. If you take any of these and develop psoriasis, tell your doctor—switching medications may help, though you should never stop taking a prescribed medication without medical guidance.

Alcohol use and smoking can both trigger flares and make existing psoriasis worse. Some people also notice that specific foods worsen their symptoms, though this varies widely from person to person.

How psoriasis affects the body beyond the skin

Psoriasis is not just a skin problem. About 30 percent of people with psoriasis develop psoriatic arthritis, a type of inflammatory arthritis that causes joint pain, stiffness, and swelling. This can happen before, during, or after skin symptoms appear, and it most commonly affects the fingers, toes, knees, and lower back.

People with psoriasis also have higher rates of certain other conditions. These include heart disease, high blood pressure, type 2 diabetes, obesity, and depression. The inflammation that drives psoriasis appears to affect the whole body, not just the skin. This is why managing psoriasis is important for overall health, not just appearance.

Psoriasis can also affect nails, causing pitting (small dents), discoloration, thickening, or crumbling. Nail psoriasis is often harder to treat than skin psoriasis and may persist even when skin clears.

Why some people develop psoriasis and others don't

Psoriasis runs in families. If one parent has psoriasis, your risk is about 10 percent. If both parents have it, your risk rises to roughly 50 percent. However, having the genetic predisposition does not may provide you will develop the condition—many people with the genes never get psoriasis.

Genetics loads the gun, but triggers pull the trigger. You need both a genetic susceptibility and an environmental trigger—stress, infection, injury, or another factor—for psoriasis to appear. This is why two siblings with the same genes may have very different experiences: one might develop psoriasis after a strep infection while the other never develops it at all.

Age also matters. Psoriasis can start at any age, but it most commonly first appears between ages 15 and 35, or sometimes after age 50. Some people have their first flare-up after a specific stressful event or illness.

The difference between psoriasis and other skin conditions

Psoriasis is often confused with eczema because both cause itchy, inflamed skin. The key difference: psoriasis patches are usually thicker, more sharply defined, and covered with silvery scales, while eczema tends to be smoother and more diffuse. Psoriasis also typically itches less intensely than eczema, though this varies.

Ringworm, a fungal infection, can look similar to some psoriasis patches, but ringworm is contagious and psoriasis is not. A doctor can confirm which one you have with a simple examination or skin scraping.

Seborrheic dermatitis, which causes flaking and redness on the scalp and face, can coexist with psoriasis but is a separate condition. Some people have both at the same time.

How doctors diagnose psoriasis

There is no blood test or single diagnostic test for psoriasis. Doctors diagnose it by examining your skin, asking about your medical history, and sometimes taking a small skin sample (biopsy) to look at under a microscope. A biopsy is usually only needed if the diagnosis is unclear.

Your doctor will ask when the patches first appeared, what triggers you have noticed, whether psoriasis runs in your family, and whether you have joint pain. They may also ask about recent infections, stress, or medication changes. This history helps them confirm psoriasis and rule out other conditions.

If you have joint pain along with skin symptoms, your doctor may order blood tests or imaging to check for psoriatic arthritis. Early detection of arthritis matters because treatment can slow joint damage.

Frequently Asked Questions

Can psoriasis go away on its own?

Psoriasis is chronic and typically does not go away permanently, but individual patches can clear up and stay clear for months or years. Some people experience long periods of remission with no symptoms. However, most people have flare-ups at some point, often triggered by stress, infection, or other factors.

Is psoriasis contagious?

No. Psoriasis is not contagious and cannot spread from person to person through touch, contact with blood, or any other means. You cannot catch it from someone else, and you cannot give it to anyone else.

What's the difference between psoriasis and a rash?

A rash is a general term for any irritation or outbreak on the skin. Psoriasis is a specific chronic condition where your immune system causes skin cells to multiply too quickly. Many rashes are temporary and caused by irritation, allergy, or infection, while psoriasis is long-lasting and driven by immune system dysfunction.

Can children get psoriasis?

Yes, though it is less common in children than adults. When psoriasis starts in childhood, it is often triggered by a strep infection. Children with psoriasis may experience the same types and severity as adults, and the condition can significantly affect their quality of life and self-image.

Does psoriasis get worse over time?

Psoriasis does not follow a predictable pattern. Some people have mild, stable disease for years. Others experience worsening over time or unpredictable flare-ups. Severity can change based on triggers, stress levels, and overall health. Working with a doctor to identify your triggers and manage the condition can help prevent worsening.