Plaque psoriasis: Plaque psoriasis is the most common type of psoriasis. About 80% to 90% of people with psoriasis have plaque psoriasis.
Guttate psoriasis: Guttate psoriasis may appear after a sore throat caused by a streptococcal infection. It looks like small, red, drop-shaped scaly spots and often affects children and young adults.
Pustular psoriasis: Pustular psoriasis has small, pus-filled bumps on top of plaques.
Erythrodermic psoriasis: This is a severe type of psoriasis that affects a large area (more than 90%) of your skin. It causes widespread skin discoloration and skin shedding.
Sebo psoriasis: This type typically appears on your face and scalp as bumps and plaques with a greasy, yellow scale. This is a cross between psoriasis and seborrheic dermatitis.
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.
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 second-hand smoke
Heavy alcohol consumption
Certain medications — including lithium, high blood pressure drugs and antimalarial drugs
Rapid withdrawal of oral or injected corticosteroids
Psoriatic arthritis is a type of arthritis that causes joint pain and swelling. Similar to psoriasis, psoriatic arthritis is an autoimmune condition that causes your immune system to function abnormally and cause symptoms. About 1 in 3 people diagnosed with psoriasis will also develop arthritis due to inflammation. Early treatment of psoriatic arthritis can reduce damage to your joints.
The appearance of a skin plaque leads to a psoriasis diagnosis, but symptoms can relate to other similar skin conditions. Skin biopsy helps determine the type of psoriasis and rule out other disorders.
How is psoriasis treated?
Choice of treatment depends on severity of psoriasis 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.
TOPICAL THERAPY
Corticosteroids: are the most commonly prescribed creams to treat mild to moderate psoriasis. They are available as oils, ointments, creams, lotions, gels, foams, sprays and shampoos. Topical corticosteroids might be applied once a day during flares, and on alternate days or weekends during remission. A stronger corticosteroid cream or ointment triamcinolone (Trianex) or clobetasol (Cormax, Temovate, others) may be prescribed for more severe symptoms.
Vitamin D analogues: slow skin cell growth. This type of drug may be used alone or with topical corticosteroids. Calcitriol may cause less irritation in sensitive areas.
Retinoids in the form of gels or cream can be applied once or twice daily. The most common side effects are skin irritation and increased sensitivity to light.
Calcineurin inhibitors: 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.
Salicylic acid: shampoos and scalp solutions reduce the scaling of scalp psoriasis. They are available in nonprescription or prescription strengths.
Coal tar: reduces scaling, itching and inflammation.
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
Light therapy (also known as phototherapy) can be combined with medications for moderate to severe psoriasis. Daily exposures to sunlight (heliotherapy) might improve psoriasis.
Calculated doses of broadband or narrow band ultraviolet B (UVB) can be administered to psoriatic patches. 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.
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.
ORAL OR INJECTED MEDICATION
For a few small, persistent psoriasis patches, your health care provider might suggest an injection of triamcinolone (steroid).
Acitretin and other retinoids are pills used to reduce the production of skin cells.
Certain drugs that alter the immune system include etanercept (Enbrel), infliximab (Remicade), adalimumab (Humira), Ustekinumab (Stelara), risankizumab-rzaa (Skyrizi). These 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 (Trexall), administered once/week, decreases the production of skin cells and suppresses inflammation.
