Psoriasis is a skin disease that causes a rash with itchy, scaly patches, most commonly on the knees, elbows, trunk and scalp.
Psoriasis is a common, long-term (chronic) disease with no cure. It can be painful, interfere with sleep and make it hard to concentrate. The condition tends to go through cycles, flaring for a few weeks or months, then subsiding for a while. Common triggers in people with a genetic predisposition to psoriasis include infections, cuts or burns, and certain medications.
Treatments are available to help you manage symptoms. And you can try lifestyle habits and coping strategies to help you live better with psoriasis.
Common signs and symptoms of psoriasis include:
- A patchy rash that varies widely in how it looks from person to person, ranging from spots of dandruff-like scaling to major eruptions over much of the body
- Rashes that vary in color, tending to be shades of purple with gray scale on brown or Black skin and pink or red with silver scale on white skin
- Small scaling spots (commonly seen in children)
- Dry, cracked skin that may bleed
- Itching, burning or soreness
- Cyclic rashes that flare for a few weeks or months and then subside
There are several types of psoriasis, each of which varies in its signs and symptoms:
- Plaque psoriasis. The most common type of psoriasis, plaque psoriasis causes dry, itchy, raised skin patches (plaques) covered with scales. There may be few or many. They usually appear on the elbows, knees, lower back and scalp. The patches vary in color, depending on skin color. The affected skin might heal with temporary changes in color (post inflammatory hyperpigmentation), particularly on brown or Black skin.
- Nail psoriasis. Psoriasis can affect fingernails and toenails, causing pitting, abnormal nail growth and discoloration. Psoriatic nails might loosen and separate from the nail bed (onycholysis). Severe disease may cause the nail to crumble.
- Guttate psoriasis. Guttate psoriasis primarily affects young adults and children. It's usually triggered by a bacterial infection such as strep throat. It's marked by small, drop-shaped, scaling spots on the trunk, arms or legs.
- Inverse psoriasis. Inverse psoriasis mainly affects the skin folds of the groin, buttocks and breasts. It causes smooth patches of inflamed skin that worsen with friction and sweating. Fungal infections may trigger this type of psoriasis.
- Pustular psoriasis. Pustular psoriasis, a rare type, causes clearly defined pus-filled blisters. It can occur in widespread patches or on small areas of the palms or soles.
- Erythrodermic psoriasis. The least common type of psoriasis, erythrodermic psoriasis can cover the entire body with a peeling rash that can itch or burn intensely. It can be short-lived (acute) or long-term (chronic).
Psoriasis is thought to be an immune system problem that causes skin cells to grow faster than usual. In the most common type of psoriasis, known as plaque psoriasis, this rapid turnover of cells results in dry, scaly patches.
The cause of psoriasis isn't fully understood. It's thought to be an immune system problem where infection-fighting cells attack healthy skin cells by mistake. Researchers believe that both genetics and environmental factors play a role. The condition is not contagious.
Many people who are predisposed to psoriasis may be free of symptoms for years until the disease is triggered by some environmental factor. Common psoriasis triggers include:
- Infections, such as strep throat or skin infections
- Weather, especially cold, dry conditions
- Injury to the skin, such as a cut or scrape, a bug bite, or a severe sunburn
- Smoking and exposure to secondhand smoke
- Heavy alcohol consumption
- Certain medications — including lithium, high blood pressure drugs and antimalarial drugs
- Rapid withdrawal of oral or injected corticosteroids
Anyone can develop psoriasis. About a third of instances begin in childhood. These factors can increase the risk of developing the disease:
- Family history. The condition runs in families. Having one parent with psoriasis increases your risk of getting the disease. And having two parents with psoriasis increases your risk even more.
- Smoking. Smoking tobacco not only increases the risk of psoriasis but also may increase the severity of the disease.
If you have psoriasis, you're at greater risk of developing other conditions, including:
- Psoriatic arthritis, which causes pain, stiffness, and swelling in and around the joints
- Temporary skin color changes (post-inflammatory hypopigmentation or hyperpigmentation) where plaques have healed
- Eye conditions, such as conjunctivitis, blepharitis and uveitis
- Type 2 diabetes
- High blood pressure
- Cardiovascular disease
- Other autoimmune diseases, such as celiac disease, sclerosis and the inflammatory bowel disease called Crohn's disease
- Mental health conditions, such as low self-esteem and depression
Psoriasis treatments aim to stop skin cells from growing so quickly and to remove scales. Options include creams and ointments (topical therapy), light therapy (phototherapy), and oral or injected medications.
Which treatments you use depends on how severe the psoriasis is and how responsive it has been to previous treatment and self-care measures. You might need to try different drugs or a combination of treatments before you find an approach that works. Even with successful treatment, usually the disease returns.
- Corticosteroids. These drugs are the most frequently prescribed medications for treating mild to moderate psoriasis. They are available as oils, ointments, creams, lotions, gels, foams, sprays and shampoos. Mild corticosteroid ointments (hydrocortisone) are usually recommended for sensitive areas, such as the face or skin folds, and for treating widespread patches. Topical corticosteroids might be applied once a day during flares, and on alternate days or weekends during remission.
Your health care provider may prescribe a stronger corticosteroid cream or ointment — triamcinolone (Trianex) or clobetasol (Cormax, Temovate, others) — for smaller, less-sensitive or tougher-to-treat areas.
Long-term use or overuse of strong corticosteroids can thin the skin. Over time, topical corticosteroids may stop working.
- Vitamin D analogues. Synthetic forms of vitamin D — such as calcipotriene (Dovonex, Sorilux) and calcitriol (Vectical) — slow skin cell growth. This type of drug may be used alone or with topical corticosteroids. Calcitriol may cause less irritation in sensitive areas. Calcipotriene and calcitriol are usually more expensive than topical corticosteroids.
- Retinoids. Tazarotene (Tazorac, Avage, others) is available as a gel or cream. It's applied once or twice daily. The most common side effects are skin irritation and increased sensitivity to light.
Tazarotene isn't recommended when you're pregnant or breastfeeding or if you intend to become pregnant.
- Calcineurin inhibitors. Calcineurin inhibitors — such as tacrolimus (Protopic) and pimecrolimus (Elidel) — calm the rash and reduce scaly buildup. They can be especially helpful in areas of thin skin, such as around the eyes, where steroid creams or retinoids are irritating or harmful.
Calcineurin inhibitors aren't recommended when you're pregnant or breastfeeding or if you intend to become pregnant. This drug is also not intended for long-term use because of a potential increased risk of skin cancer and lymphoma.
- Salicylic acid. Salicylic acid shampoos and scalp solutions reduce the scaling of scalp psoriasis. They are available in nonprescription or prescription strengths. This type of product may be used alone or with other topical therapy, as it prepares the scalp to absorb the medication more easily.
- Coal tar. Coal tar reduces scaling, itching and inflammation. It's available in nonprescription and prescription strengths. It comes in various forms, such as shampoo, cream and oil. These products can irritate the skin. They're also messy, stain clothing and bedding, and can have a strong odor.
Coal tar treatment isn't recommended when you're pregnant or breastfeeding.
- Anthralin. Anthralin is a tar cream that slows skin cell growth. It can also remove scales and make skin smoother. It's not intended for use on the face or genitals. Anthralin can irritate skin, and it stains almost anything it touches. It's usually applied for a short time and then washed off.
Light therapy is a first line treatment for moderate to severe psoriasis, either alone or in combination with medications. It involves exposing the skin to controlled amounts of natural or artificial light. Repeated treatments are necessary. Talk with your health care provider about whether home phototherapy is an option for you.
- Sunlight. Brief, daily exposures to sunlight (heliotherapy) might improve psoriasis. Before beginning a sunlight regimen, ask your health care provider about the safest way to use natural light for psoriasis treatment.
- Goeckerman therapy. An approach that combines coal tar treatment with light therapy is called the Goeckerman therapy. This can be more effective because coal tar makes skin more responsive to ultraviolet B (UVB) light.
- UVB broadband. Controlled doses of UVB broadband light from an artificial light source can treat single psoriasis patches, widespread psoriasis and psoriasis that doesn't improve with topical treatments. Short-term side effects might include inflamed, itchy, dry skin.
- UVB narrowband. UVB narrowband light therapy might be more effective than UVB broadband treatment. In many places it has replaced broadband therapy. It's usually administered two or three times a week until the skin improves and then less frequently for maintenance therapy. But narrowband UVB phototherapy may cause more-severe side effects than UVB broadband.
- Psoralen plus ultraviolet A (PUVA). This treatment involves taking a light-sensitizing medication (psoralen) before exposing the affected skin to UVA light. UVA light penetrates deeper into the skin than does UVB light, and psoralen makes the skin more responsive to UVA exposure.
This more aggressive treatment consistently improves skin and is often used for more-severe psoriasis. Short-term side effects might include nausea, headache, burning and itching. Possible long-term side effects include dry and wrinkled skin, freckles, increased sun sensitivity, and increased risk of skin cancer, including melanoma.
- Excimer laser. With this form of light therapy, a strong UVB light targets only the affected skin. Excimer laser therapy requires fewer sessions than does traditional phototherapy because more-powerful UVB light is used. Side effects might include inflammation and blistering.
Oral or injected medications
If you have moderate to severe psoriasis, or if other treatments haven't worked, your health care provider may prescribe oral or injected (systemic) drugs. Some of these drugs are used for only brief periods and might be alternated with other treatments because they have potential for severe side effects.
- Steroids. If you have a few small, persistent psoriasis patches, your health care provider might suggest an injection of triamcinolone right into them.
- Retinoids. Acitretin and other retinoids are pills used to reduce the production of skin cells. Side effects might include dry skin and muscle soreness. These drugs are not recommended when you're pregnant or breastfeeding or if you intend to become pregnant.
- Biologics. These drugs, usually administered by injection, alter the immune system in a way that disrupts the disease cycle and improves symptoms and signs of disease within weeks. Several of these drugs are approved for the treatment of moderate to severe psoriasis in people who haven't responded to first line therapies. Options include apremilast (Otezla), etanercept (Enbrel), infliximab (Remicade), adalimumab (Humira), ustekinumab (Stelara), secukinumab (Cosentyx), ixekizumab (Taltz), guselkumab (Tremfya), tildrakizumab (Ilumya) and certolizumab (Cimzia). Three of them — etanercept, ixekizumab and ustekinumab — are approved for children. These types of drugs are expensive and may or may not be covered by health insurance plans.
Biologics must be used with caution because they carry the risk of suppressing the immune system in ways that increase the risk of serious infections. People taking these treatments must be screened for tuberculosis.
- Methotrexate. Usually administered weekly as a single oral dose, methotrexate (Trexall) decreases the production of skin cells and suppresses inflammation. It's less effective than adalimumab and infliximab. It might cause upset stomach, loss of appetite and fatigue. People taking methotrexate long-term need ongoing testing to monitor their blood counts and liver function.
People need to stop taking methotrexate at least three months before attempting to conceive. This drug is not recommended for those who are breastfeeding.
- Cyclosporine. Taken orally for severe psoriasis, cyclosporine (Gengraf, Neoral, Sandimmune) suppresses the immune system. It's similar to methotrexate in effectiveness but cannot be used continuously for more than a year. Like other immunosuppressant drugs, cyclosporine increases the risk of infection and other health problems, including cancer. People taking cyclosporine long-term need ongoing testing to monitor their blood pressure and kidney function.
These drugs aren't recommended when you're pregnant or breastfeeding or if you intend to become pregnant.
- Other medications. Thioguanine (Tabloid) and hydroxyurea (Droxia, Hydrea) are medications that can be used when you can't take other drugs. Talk with your health care provider about possible side effects of these drugs.
You and your health care provider will choose a treatment approach based on your needs and the type and severity of your psoriasis. You'll likely start with the mildest treatments — topical creams and ultraviolet light therapy (phototherapy). Then, if your condition doesn't improve, you might move on to stronger treatments.
People with pustular or erythrodermic psoriasis usually need to start with stronger (systemic) medications.
In any situation, the goal is to find the most effective way to slow cell turnover with the fewest possible side effects.