Medically Reviewed by Poonam Sachdev on April 25, 2023

Psoriasis is a skin disorder that causes skin cells to multiply up to 10 times faster than normal. This makes the skin build up into bumpy red patches covered with white scales. On darker skin, the patches can be purplish, violet, or brown with gray scales. They can grow anywhere, but most appear on the scalp, elbows, knees, and lower back. Psoriasis can't be passed from person to person. It does sometimes happen in members of the same family.

Yes. Psoriasis usually appears in early adulthood. For most people, it affects just a few areas. In severe cases, psoriasis can cover large parts of the body. The patches can heal and then come back throughout a person's life.

Psoriasis is a lifelong condition that can go through periods of remission and flare-ups, but there is currently no known cure.

The symptoms of psoriasis vary depending on the type you have. Some common symptoms for plaque psoriasis (which is the most common variety of the condition) include:

  • Plaques of red skin, often covered with silver-colored scales. In darker skin tones, plaques may be brown or purplish with gray scales. These plaques may be itchy and painful, and they sometimes crack and bleed. In severe cases, the plaques will grow and merge, covering large areas.
  • Disorders of the fingernails and toenails, including discoloration and pitting of the nails. The nails may also crumble or detach from the nail bed.
  • Plaques of scales or crust on the scalp.

People with psoriasis can also get a type of arthritis called psoriatic arthritis. It causes pain and swelling in the joints. The National Psoriasis Foundation estimates that between 10% to 30% of people with psoriasis also have psoriatic arthritis.

Other types of psoriasis include:

  • Pustular psoriasis, which causes discolored, scaly skin with tiny pustules on the palms of the hands and soles of the feet.
  • Guttate psoriasis, which often starts in childhood or young adulthood, causes small spots that are pink, red, brown, or purple in color, mainly on the torso and limbs. Triggers may be respiratory infections, strep throat, tonsillitis, stress, injury to the skin, and taking antimalarial and beta-blocker medications.
  • Inverse psoriasis, which causes discolored, shiny lesions that appear in skin folds, such as the armpits, groin, and under the breasts. On light skin, the lesions will be bright red. On darker skin, they'll be darker than the surrounding skin and can be purplish or brown in color. 
  • Erythrodermic psoriasis, which causes intense discoloration of the skin and shedding of scales in sheets. It's triggered by severe sunburn, infections, certain medications, and stopping some kinds of psoriasis treatment. It needs to be treated immediately because it can lead to severe illness.

No one knows the exact cause of psoriasis, but experts believe that it’s a combination of things. Something wrong with the immune system causes inflammation, triggering new skin cells to form too quickly. Normally, skin cells are replaced every 10-30 days. With psoriasis, new cells grow every 3-4 days. The buildup of old cells being replaced by new ones creates the scales. The exact cause of psoriasis is still a mystery; however, researchers think it is caused when something sets off your immune system. But it's probably a combination of risk factors and triggers.

Psoriasis tends to run in families, but it may skip generations. For instance, a grandfather and their grandson may be affected, but not the child's mother.

Things that can trigger an outbreak of psoriasis include:

  • Cuts, scrapes, or surgery
  • Emotional stress
  • Strep infections
  • Medications, including blood pressure medications, anti-malarial drugs, lithium and other mood stabilizers, antibiotics, and NSAIDs

Physical exam. It’s usually easy for your doctor to diagnose psoriasis, especially if you have plaques on areas such as your:

  • Scalp
  • Ears
  • Elbows
  • Knees
  • Belly button
  • Nails

Your doctor will give you a full physical exam and ask if people in your family have psoriasis.

Lab tests. The doctor might do a biopsy -- remove a small piece of skin and test it to make sure you don’t have a skin infection. There’s no other test to confirm or rule out psoriasis.

Luckily, there are many treatments. Some slow the growth of new skin cells, and others relieve itching and dry skin. Your doctor will select a treatment plan that is right for you based on the size and location of your rash, your age, your overall health, and other things. Common treatments include:

  • Steroid creams
  • Moisturizers for dry skin
  • Coal tar (a common treatment for scalp psoriasis available in lotions, creams, foams, shampoos, and bath solutions)
  • Vitamin D-based cream or ointment (a strong kind ordered by your doctor -- vitamin D in foods and pills has no effect)
  • Retinoid creams
  • Calcineurin inhibitors
  • Anthralin

Treatments for moderate to severe psoriasis include:

  • Light therapy. A doctor shines ultraviolet light on your skin to slow the growth of skin cells. Psoralen plus ultraviolet-A radiation (PUVA) is a treatment that combines a medicine called psoralen with a special form of ultraviolet light.
  • Methotrexate. This drug can cause bone marrow and liver disease as well as lung problems, so it’s only for serious cases, and doctors closely watch patients who take this drug. You will have to get lab tests, perhaps a chest X-ray, and possibly a liver biopsy.
  • Retinoids. These pills, creams, foams, lotions, and gels are a class of drugs related to vitamin A. Retinoids can cause serious side effects, including birth defects, so they’re not recommended for women who are pregnant or planning to have children.
  • Cyclosporine. This drug, made to suppress the immune system, may be taken for serious cases that do not respond to other treatments. It can damage the kidneys and raise blood pressure, so your doctor will closely watch your health while you take it.
  • Biologic treatments. These work by blocking the part of the body's immune system that is overactive in psoriasis. Biologic medications include adalimumab (Humira), brodalumab (Siliq), certolizumab pegol (Cimzia) etanercept (Enbrel), guselkumab (Tremfya), infliximab (Remicade), ixekizumab (Taltz), risankizumab-rzaa (SKYRIZI), secukinumab (Cosentyx), tildrakizumab (Ilumya), and ustekinumab (Stelara).
  • Enzyme inhibitors. The medications, apremilast (Otezla) or deucravacitinib (Sotyktu), are new kinds of drug for long-term inflammatory diseases, such as psoriasis and psoriatic arthritis. They are pills that block a specific enzyme, which helps slow other reactions that lead to inflammation.
  • An aryl hydrocarbon receptor (AHR) agonist. Tapinarof (Vtama) is a steroid-free, once-a-day topical cream, which can be used on all body areas, including most sensitive locations except the eyes and inside the vagina.

Genes: Little bits of your DNA, called genes, carry instructions for your cells. They control your eye and hair color, your ability to taste certain things, and the other ways your body works. Some genes are active only at certain times.

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

Scientists have found more than 80 genes that are different in people with psoriasis. They think it takes more than one gene 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.

AlcoholHeavy drinkers are at a higher risk, especially younger men. Moreover, alcohol can make treatments less effective.

Smoking: Lighting up can double your risk of getting psoriasis. If you also have relatives with the condition, you're nine times more likely to get it. And smoking makes it harder to get rid of symptoms. It's closely linked to a hard-to-treat type called pustular psoriasis, which affects the palms of your hands and the soles of your feet.

Hormone changes: The condition often shows up or flares during puberty. Menopause can also trigger it. During pregnancy, your symptoms may get better or even go away. But after the baby’s born, you might have a flare.

Stress: Scientists think your immune system may respond to emotional and mental pressures the same way it does to physical problems, such as injuries and infections.

Medications: Some treatments can make psoriasis worse. These include:

  • Lithium, which treats bipolar disorder and other mental illnesses
  • High blood pressure and heart medicines, including propranolol (Inderal) and other beta-blockers, angiotensin-converting enzyme inhibitors, and quinidine
  • Antimalarial medicines, including chloroquine, hydroxychloroquine (Plaquenil), and quinacrine
  • Indomethacin (Indocin), which treats inflammation

Steroid withdrawal: Topical steroids (medications that fight inflammation, in forms that you put on your skin) are some of the most common psoriasis treatments. But they can also cause symptom flares if you stop using them too quickly.

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

Other infections: Strep infections, in particular, are linked to guttate psoriasis, which looks like small red drops. Kids often have strep throat before their first flare. Earaches, bronchitis, tonsillitis, or a respiratory infection such as a cold or the flu may also be triggers.

Sunlight: A little natural light is good for most people with psoriasis. But for a few, the sun makes their condition worse and so can a bad sunburn. Hence, protect your skin if you’re going to be outside.

Skin injuries: A cut, scrape, bug bite, infection, or too much scratching can trigger the condition.

Weight: People who are obese tend to get plaques in their skin creases and folds.

Weather: Your psoriasis might get worse in the winter. Dry air, less natural sunlight, and cold temperatures can make symptoms worse. Keep your skin moist, and try a humidifier at home.

There’s no cure, but treatment greatly reduces symptoms, even in serious cases. Recent studies have suggested that when you better control the inflammation of psoriasis, your risk for heart disease, stroke, metabolic syndrome, and other diseases associated with inflammation goes down.

Psoriasis affects:

  • 2%-3% of people throughout the world
  • About 3% of people in the United States
  • Some cultures more than others. Worldwide, psoriasis is most common in northern Europe and least common in eastern Asia.

Show Sources

Photo Credit: Allan Harris/Medical Images


National Institute of Arthritis and Musculoskeletal and Skin Disease.

National Psoriasis Foundation.

The Psoriasis Foundation.

American Academy of Dermatology.

UpToDate: “Epidemiology, clinical manifestations, and diagnosis of psoriasis.”

FDA: "FDA approves new psoriasis drug Taltz," "FDA approves Amjevita, a biosimilar to Humira."

Medscape: "FDA OKs Biologic Guselkumab (Tremfya) for Plaque Psoriasis."

National Psoriasis Foundation: “Statistics,” "Inverse Psoriasis." 

PubMed Health: "Plaque Psoriasis."

World Health Organization: “Global report on psoriasis.”

Mayo Clinic - Photo Caption

National Library of Medicine - Photo Caption

Precision Clinical Medicine: “Genetics of psoriasis: a basis for precision medicine.”


Photo credit: Science Photo Library/Science Source

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