Psoriasis is an inflammatory skin condition caused by an overactive immune system that causes skin cells to grow and divide faster than normal.1 According to the National Psoriasis Foundation, there are five types of psoriasis — each is associated with different symptoms and can affect certain parts of the body.2
In this article, we’ll discuss what causes psoriasis and detail the different types. We’ll also go over symptoms to be aware of and tests your doctor or dermatologist may use to give you a diagnosis. The sooner you receive a psoriasis diagnosis, the sooner you can begin treatment to help clear your skin and relieve your skin inflammation, itching, and pain.
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What Causes Psoriasis?
Psoriasis is an autoimmune-mediated condition — this means that doctors and researchers know that excess inflammation plays a role in psoriasis, but they’re not exactly sure what causes it.3 It’s important to note that psoriasis isn’t contagious, meaning it can’t be passed from one person to another. They believe it may be due to a combination of your environment and genetics.
Environmental Triggers of Psoriasis
When your psoriasis symptoms get worse in a short period of time, it’s known as having a flare. These episodes can be brought on by triggers in your environment that kick your immune system into overdrive. This creates more inflammation that affects your skin and, occasionally, other areas of your body.4
Examples of psoriasis triggers include:
- Bacterial infections that lead to upper respiratory tract infections, ear infections, etc.
- Skin injuries like cuts, scrapes, sunburn, or bug bites
- Allergic reactions to substances like pollen, alcohol, certain foods, medications
- Stress and anxiety
- Cold, dry weather
Genetics of Psoriasis
Psoriasis tends to run in families, meaning if a close family member is affected, you’re more likely to develop it yourself. Studies show that if you have a parent or sibling with psoriasis, your chances increase to 15 percent and 20 percent, respectively.5
There’s no one specific gene that increases your risk of psoriasis. Instead, researchers have found over 60 genes that may contribute to your chances of developing this skin condition.6 Many of them are involved in your immune system function — including how your immune cells work and the inflammatory signals they use to communicate with one another.
Skin Inflammation and Psoriasis
Your skin cells are constantly being replaced to keep your skin barrier healthy and to protect you from the environment. Normally, the process for your skin cells to grow and shed takes around one month. Excess inflammation from psoriasis speeds up this process to happen in around 3 to 4 days. When your skin cells grow and divide too quickly, they don’t shed properly.7
Instead, the extra skin cells begin building up on your skin’s surface. This creates inflamed, raised plaques or scales that can sting, itch, and burn. Depending on the type of psoriasis you have, you may find plaques anywhere on your body. The most commonly affected areas include the knees, elbows, and scalp.
Types of Psoriasis
There are five main types of psoriasis, and each is associated with its own set of symptoms. The most common type is plaque psoriasis, accounting for the majority of cases. We’ll also talk about the less common and even rare types of psoriasis, so you know what symptoms to look out for.
Plaque Psoriasis
When you think of classic psoriasis symptoms, you likely think of plaque psoriasis. This is the most common type of psoriasis, affecting between 80 to 90 percent of people living with this skin condition. In the United States, it affects around 6.7 million adults in total.8
Plaque psoriasis (also known as psoriasis vulgaris) creates thick plaques or scales on the skin. They often appear on the elbows, knees, lower back, and scalp. In severe cases, you may also notice plaques on your hands, legs, feet, face, and genitals. These plaques may be painful, dry, or itchy. Thicker scales and plaques can also crack open (known as fissures) and bleed.8
Plaques may appear differently depending on your skin tone. On lighter skin, they often look like raised, red scales covered in white or silvery dead skin. On darker skin tones, plaques are usually thicker and darker, with more of a gray, purple, or brown color.9
People with plaque psoriasis may also develop nail psoriasis years after they’re diagnosed.10 Some people have nail psoriasis without showing any signs of plaque psoriasis. Both your fingernails and toenails can be affected, so be sure to check them regularly. Symptoms of nail psoriasis to be aware of include:
- Crumbling nail
- Pitting or small dents in your nail
- Nail discoloration (yellow, white, or brown coloring)
- Dead skin cell buildup or blood underneath your nails
- Separation of your nail from the nail bed
Inverse Psoriasis
Inverse psoriasis is a type of psoriasis that affects areas where your skin rubs together, including your groin, armpits, or underneath your breasts.11 Skin folds in your belly, underneath your buttocks, or in your inner thighs or neck can also be affected. According to the National Psoriasis Foundation, up to 30 percent of people with psoriasis will develop inverse psoriasis at some point in their lives.
People who are overweight or obese and those with deep skin folds tend to be affected by inverse psoriasis more.11 This is because their skin rubs together more often, creating friction and inflammation that causes irritation. Other factors that increase your risk of inverse psoriasis include:
- Alcohol use
- Smoking tobacco
- Stress and anxiety
- Low levels of vitamin D
Inverse psoriasis can appear as smooth, shiny, discolored skin that varies based on your skin tone. In people with lighter skin tones, rashes tend to be pink or bright red. For those with darker skin tones, rashes are often purple or brown. Plaques and scales typically don’t form in inverse psoriasis because the affected skin is moist.12
Guttate Psoriasis
Guttate psoriasis affects around eight percent of people living with psoriasis.13 It’s characterized by the presence of papules or small, raised, round or teardrop-shaped red spots on the skin.
These papules can often be found on your arms, legs, and torso. Less commonly, they can also be found on your scalp, ears, and face. You might notice that your skin becomes dry and peels off over the papules, making them red, irritated, and itchy at times.14
Unlike other types of psoriasis, guttate psoriasis symptoms appear suddenly. The most common trigger of this psoriasis type is a Group A Streptococcus infection, which is responsible for causing strep throat.13 As a result, guttate psoriasis is more common in children than adults, but it can develop at any age. Studies show that around 40 percent of people with guttate psoriasis will go on to develop plaque psoriasis.15
Other known conditions or triggers of guttate psoriasis include:13
- Upper respiratory infections, sinus infections, or influenza (the flu)
- Taking certain medications, like beta-blockers (blood pressure medications) or antimalarials (help prevent or treat malaria)
- Skin injuries like cuts or burns
- Stress or anxiety
- Tonsillitis or inflammation of your tonsils (tissues found in the back of your throat)
If you have a weakened immune system, you’re also more likely to develop guttate psoriasis.14 This is especially true if you’re undergoing cancer treatment with chemotherapy or living with an autoimmune disorder like rheumatoid arthritis or if you’ve been infected with human immunodeficiency virus (HIV).
Pustular Psoriasis
A less common type of psoriasis is pustular psoriasis, which accounts for around three percent of all cases.16 It’s characterized by the formation of large white or yellow pus-filled blisters — known as pustules — that form on your skin. Within 1 to 2 days of appearing, the pustules merge together and burst open. The pus inside becomes exposed and dries, making your skin red and tender to the touch. New pustules can form over the burst ones, creating a cycle that can be difficult to control.17
Common triggers of pustular psoriasis include:16
- Starting or stopping certain medications, like corticosteroids
- Overexposure to sunlight or ultraviolet (UV) rays
- Stress
- Pregnancy
- Bacterial infections
Palmoplantar pustular psoriasis (PPPP) is the most common form, which creates pustules on the palms of your hands and the bottoms of your feet.18 After they burst, the pustules may dry and crack, creating bleeding fissures. Studies estimate that around 16 percent of people with PPPP also have plaque psoriasis.
Generalized pustular psoriasis (GPP) — also known as von Zumbusch psoriasis — affects large areas of skin all over your body.19 GPP tends to flare suddenly and severely, lasting for several weeks at a time. Interestingly, symptoms typically disappear spontaneously, clearing up some or all of your skin.
GPP has the potential to become life-threatening if your blood pressure suddenly drops. Call 911 or seek medical attention immediately if you begin experiencing any of the following GPP symptoms:
- Fever
- Chills
- Elevated heart rate (fast pulse)
- Joint aches and pain
- Headache
- Fatigue
- Nausea
- Intense skin itching
Erythrodermic Psoriasis
Erythrodermic psoriasis is a rare type of psoriasis that affects only two percent of those living with psoriasis.20,21 People with erythrodermic psoriasis often have symptoms affecting their entire body, which can become life-threatening if they’re not treated.
If you notice any of the following symptoms, call 911 or seek medical attention immediately:
- Skin shedding and severe redness covering large areas of skin
- Severe skin pain, burning, or itching
- Skin that looks like it’s been burned
- Fingernails or toenails falling off
- Fast pulse
- Skin peeling off in large “sheets” rather than small flakes or scales
- Large swings in body temperature, especially on hot or cold days
- Shivering or chills
- Edema or swelling in your legs, feet, or ankles caused by fluid buildup
It’s thought that around one-third of people with erythrodermic psoriasis also have plaque psoriasis. Certain situations can trigger your symptoms, including allergic reactions to medications, severe sunburn, anxiety or stress, or alcohol or substance use disorders.20,21
How Is Psoriasis Diagnosed?
If you’re experiencing any symptoms of psoriasis, make an appointment with your primary care provider. They’ll be able to refer you to a dermatologist or a doctor who specializes in treating skin conditions. This is important because psoriasis symptoms can also be mistaken for other conditions like eczema.22,23
Your dermatologist will use the results of your medical history, physical exam, and a handful of other tests to make a final diagnosis. They’ll first start by asking about your symptoms, allergies, and family history of psoriasis and other skin conditions. Your dermatologist may also ask if you’ve recently been sick (especially with strep throat) or if you’ve had a recent life event that could increase your stress levels.
During your physical exam, your dermatologist will look closely at your skin and note if you have any scales, plaques, papules, pustules, or rashes. Be sure to tell them how long your symptoms have lasted and whether there are any triggers that cause them or make them worse.
They may also choose to take a small piece of skin (known as a biopsy) to look at it under a microscope. This close-up look at your skin cells can tell your dermatologist if you have psoriasis or another skin condition.24
Once you receive a psoriasis diagnosis, your dermatologist will work with you to come up with a treatment plan to help control your symptoms.
Complications of Psoriasis
The most common complication of psoriasis is psoriatic arthritis (PsA), an inflammatory joint condition that affects around 30 percent of people living with psoriasis.25 Along with your psoriasis symptoms, you may also have:
- Painful, swollen, throbbing, or tender joints
- Swollen fingers and toes (dactylitis)
- Stiff joints when first waking up in the morning
- Limited range of motion in your joints
- Fatigue
- Inflammation or redness and pain affecting your eyes (uveitis)
PsA symptoms can affect anyone at any age (even children and teenagers), but it’s more common in adults between the ages of 30 and 50. Some people experience PsA symptoms before they develop psoriasis, while others aren’t affected until years after their initial psoriasis diagnosis.
Other complications that affect people with psoriasis include:26
- Obesity
- High blood pressure
- Type 2 diabetes
- Skin discoloration and pigment changes near healed plaques
- Eye inflammation and infections
- Depression and anxiety
- Other autoimmune diseases, such as inflammatory bowel disease
Can Psoriasis Be Prevented or Cured?
Unfortunately, there’s currently no way to cure psoriasis or prevent it from developing.27 However, you can take steps to help prevent psoriasis flares.28 For example, if stress makes your psoriasis symptoms worse, you can work on finding ways better manage it. The American Academy of Dermatology Association recommends trying yoga or other stress-relieving exercises.
Be sure to avoid your triggers as best you can. If you’re starting or stopping a medication, work with your doctor to prevent a psoriasis flare. If you smoke or drink alcohol regularly, stopping may help control skin inflammation and psoriasis symptoms. Taking extra precautions to protect your skin from cuts, bites, and UV light can also help prevent flares.28
Resources for Living with Psoriasis
If you’re living with psoriasis and/or PsA, you may be interested in meeting others who are in the same situation. There are several patient support groups and websites with resources to help you live a healthier, more comfortable life with psoriasis. Use the sources below to learn more about psoriasis and connect with others who understand.
