Psoriasis signs and symptoms can vary from person to person but may include one or more of the following:
- Red patches of skin covered with silvery scales
- Small scaling spots (commonly seen in children)
- Dry, cracked skin that may bleed
- Itching, burning or soreness
- Thickened, pitted or ridged nails
- Swollen and stiff joints
Psoriasis patches can range from a few spots of dandruff-like scaling to major eruptions that cover large areas.
Most types of psoriasis go through cycles, flaring for a few weeks or months, then subsiding for a time or even going into complete remission.
Several types of psoriasis exist. These include:
- Plaque psoriasis. The most common form, plaque psoriasis causes dry, raised, red skin lesions (plaques) covered with silvery scales. The plaques itch or may be painful and can occur anywhere on your body, including your genitals and the soft tissue inside your mouth. You may have just a few plaques or many.
- Nail psoriasis. Psoriasis can affect fingernails and toenails, causing pitting, abnormal nail growth and discoloration. Psoriatic nails may become loose and separate from the nail bed (onycholysis). Severe cases may cause the nail to crumble.
- Scalp psoriasis. Psoriasis on the scalp appears as red, itchy areas with silvery-white scales. The red or scaly areas often extend beyond the hairline. You may notice flakes of dead skin in your hair or on your shoulders, especially after scratching your scalp.
- Guttate psoriasis. This primarily affects young adults and children. It's usually triggered by a bacterial infection such as strep throat. It's marked by small, water-drop-shaped sores on your trunk, arms, legs and scalp. The sores are covered by a fine scale and aren't as thick as typical plaques are. You may have a single outbreak that goes away on its own, or you may have repeated episodes.
- Inverse psoriasis. Mainly affecting the skin in the armpits, in the groin, under the breasts and around the genitals, inverse psoriasis causes smooth patches of red, inflamed skin. It's worsened by friction and sweating. Fungal infections may trigger this type of psoriasis.
- Pustular psoriasis. This uncommon form of psoriasis can occur in widespread patches (generalized pustular psoriasis) or in smaller areas on your hands, feet or fingertips. It generally develops quickly, with pus-filled blisters appearing just hours after your skin becomes red and tender. The blisters may come and go frequently. Generalized pustular psoriasis can also cause fever, chills, severe itching and diarrhea.
- Erythrodermic psoriasis. The least common type of psoriasis, erythrodermic psoriasis can cover your entire body with a red, peeling rash that can itch or burn intensely.
- Psoriatic arthritis. In addition to inflamed, scaly skin, psoriatic arthritis causes pitted, discolored nails and the swollen, painful joints that are typical of arthritis. Symptoms range from mild to severe, and psoriatic arthritis can affect any joint. Although the disease usually isn't as crippling as other forms of arthritis, it can cause stiffness and progressive joint damage that in the most serious cases may lead to permanent deformity.
When to see a doctor
If you suspect that you may have psoriasis, see your doctor for an examination. Also, talk to your doctor if your psoriasis:
- Progresses beyond the nuisance stage, causing you discomfort and pain
- Makes performing routine tasks difficult
- Causes you concern about the appearance of your skin
- Leads to joint problems, such as pain, swelling or inability to perform daily tasks
Seek medical advice if your signs and symptoms worsen or don't improve with treatment. You may need a different medication or a combination of treatments to manage the psoriasis.
The cause of psoriasis isn't fully known, but it's thought to be related to an immune system problem with cells in your body. More specifically, one key cell is a type of white blood cell called a T lymphocyte or T cell. Normally, T cells travel throughout the body to detect and fight off foreign substances, such as viruses or bacteria. If you have psoriasis, however, the T cells attack healthy skin cells by mistake, as if to heal a wound or to fight an infection.
Overactive T cells trigger other immune responses. The effects include dilation of blood vessels in the skin around the plaques and an increase in other white blood cells that can enter the outer layer of skin. These changes result in an increased production of both healthy skin cells and more T cells and other white blood cells. This causes an ongoing cycle in which new skin cells move to the outermost layer of skin too quickly — in days rather than weeks. Dead skin and white blood cells can't slough off quickly enough and build up in thick, scaly patches on the skin's surface. This usually doesn't stop unless treatment interrupts the cycle.
Just what causes T cells to malfunction in people with psoriasis isn't entirely clear. Researchers have found genes that are linked to the development of psoriasis, but environmental factors also play a role.
Psoriasis typically starts or worsens because of a trigger that you may be able to identify and avoid. Factors that may trigger psoriasis include:
- Infections, such as strep throat or skin infections
- Injury to the skin, such as a cut or scrape, bug bite, or a severe sunburn
- Cold weather
- Heavy alcohol consumption
- Certain medications — including lithium, which is prescribed for bipolar disorder; high blood pressure medications such as beta blockers; antimalarial drugs; and iodides.
Anyone can develop psoriasis, but these factors can increase your risk of developing the disease:
- Family history. Perhaps the most significant risk factor for psoriasis is having a family history of the disease. Having one parent with psoriasis increases your risk of getting the disease, and having two parents with psoriasis increases your risk even more.
- Viral and bacterial infections. People with HIV are more likely to develop psoriasis than people with healthy immune systems are. Children and young adults with recurring infections, particularly strep throat, also may be at increased risk.
- Stress. Because stress can impact your immune system, high stress levels may increase your risk of psoriasis.
- Obesity. Excess weight increases the risk of psoriasis. Plaques associated with all types of psoriasis often develop in skin creases and folds.
- Smoking. Smoking tobacco not only increases your risk of psoriasis but also may increase the severity of the disease. Smoking may also play a role in the initial development of the disease.
If you have psoriasis, you're at greater risk of developing certain diseases. These include:
- Psoriatic arthritis. This complication of psoriasis can cause joint damage and a loss of function in some joints, which can be debilitating.
- Eye conditions. Certain eye disorders — such as conjunctivitis, blepharitis and uveitis — are more common in people with psoriasis.
- Obesity. People with psoriasis, especially those with more severe disease, are more likely to be obese. It's not clear how these diseases are linked, however. The inflammation linked to obesity may play a role in the development of psoriasis. Or it may be that people with psoriasis are more likely to gain weight, possibly because they're less active because of their psoriasis.
- Type 2 diabetes. The risk of type 2 diabetes is upped in people with psoriasis. The more severe the psoriasis, the greater the likelihood of type 2 diabetes.
- High blood pressure. The odds of having high blood pressure are higher for people with psoriasis.
- Cardiovascular disease. For people with psoriasis, the risk of heart attack is almost three times greater than for those without the disease. The risk of irregular heartbeats and stroke is also higher in those with psoriasis. This could be due to excess inflammation or to an increased risk of obesity and other risk factors for cardiovascular disease. Some psoriasis treatments may cause abnormal cholesterol levels and increase the risk of hardened arteries.
- Metabolic syndrome. This is a cluster of conditions — including high blood pressure, elevated insulin levels and abnormal cholesterol levels — that increases your risk of heart disease. People with psoriasis have a higher risk of metabolic syndrome.
- Other autoimmune diseases. Celiac disease, sclerosis and the inflammatory bowel disease called Crohn's disease are more likely to strike people with psoriasis.
- Parkinson's disease. This chronic neurological condition is more likely to occur in people with psoriasis.
- Kidney disease. Moderate to severe psoriasis has been linked to a higher risk of kidney disease.
Psoriasis can also affect your quality of life by increasing your risk of:
- Low self-esteem
- Social isolation
- Problems at work, which can lead to a lower income