What is psoriasis?
Psoriasis is a long-term skin condition that is characterized by patches of thick, red skin covered with silvery scales. These patches are known as plaques. Plaques can develop anywhere on the body but most often appear on the elbows, legs (including knees), lower back, scalp, palms of the hands and soles of the feet. Psoriasis can also affect the fingernails and toenails, the genital area, the joints and the inside of the mouth. It affects female and males equally and usually develops in adulthood, although it can affect younger people. Psoriasis is not contagious and does not spread by touch from person to person.
What causes psoriasis?
Psoriasis is a disorder of the immune system. Normally the body’s white blood cells (specifically the T cells) help to protect against infection and disease. In someone with psoriasis, the T cells are activated by mistake, causing the body’s immune system to over-react. This leads to inflammation and excess growth of skin cells, which build up to form plaques. Research suggests that psoriasis is inherited to some extent, and certain genes have been identified that are linked to the development of psoriasis.
Psoriasis can flare up for no reason or may worsen because of triggers such as infections, changes in the weather, dry skin and the use of certain medications.
What will be the treatment approach.
Psoriasis treatments can be divided into three main types: topical treatments, light therapy and systemic medications.
Used alone, creams and ointments that you apply to your skin can effectively treat mild to moderate psoriasis. When the disease is more severe, creams are likely to be combined with oral medications or light therapy. Topical psoriasis treatments include:
Topical corticosteroids. These powerful anti-inflammatory drugs are the most frequently prescribed medications for treating mild to moderate psoriasis. They slow cell turnover by suppressing the immune system, which reduces inflammation and relieves associated itching. Topical corticosteroids range in strength, from mild to very strong.
Vitamin D analogues. These synthetic forms of vitamin D slow down the growth of skin cells. Calcipotriene (Dovonex) is a prescription cream or solution containing a vitamin D analogue that may be used alone to treat mild to moderate psoriasis or in combination with other topical medications or phototherapy. This treatment can irritate the skin. Calcitriol (Rocaltrol) is expensive but may be equally effective and possibly less irritating than calcipotriene.
Anthralin. This medication is believed to normalize DNA activity in skin cells. Anthralin (Dritho-Scalp) also can remove scale, making the skin smoother. However, anthralin can irritate skin, and it stains virtually anything it touches, including skin, clothing, countertops and bedding. For that reason, doctors often recommend short-contact treatment — allowing the cream to stay on your skin for a brief time before washing it off.
Topical retinoids. These are commonly used to treat acne and sun-damaged skin, but tazarotene (Tazorac, Avage) was developed specifically for the treatment of psoriasis. Like other vitamin A derivatives, it normalizes DNA activity in skin cells and may decrease inflammation. The most common side effect is skin irritation. It may also increase sensitivity to sunlight, so sunscreen should be applied while using the medication. Although the risk of birth defects is far lower for topical retinoids than for oral retinoids, tazarotene isn't recommended when you're pregnant or breast-feeding or if you intend to become pregnant.
Calcineurin inhibitors. Currently, calcineurin inhibitors — tacrolimus (Prograf) and pimecrolimus (Elidel) — are approved only for the treatment of atopic dermatitis, but studies have shown them to be effective at times in the treatment of psoriasis. Calcineurin inhibitors are thought to disrupt the activation of T cells, which, in turn, reduces inflammation and plaque buildup.
Calcineurin inhibitors are not recommended for long-term or continuous use because of a potential increased risk of skin cancer and lymphoma. They may be especially helpful in areas of thin skin, such as around the eyes, where steroid creams or retinoids are too irritating or may cause harmful effects.
Salicylic acid. Available over-the-counter (nonprescription) and by prescription, salicylic acid promotes sloughing of dead skin cells and reduces scaling. Sometimes it's combined with other medications, such as topical corticosteroids or coal tar, to increase its effectiveness. Salicylic acid is available in medicated shampoos and scalp solutions to treat scalp psoriasis.
Coal tar. A thick, black byproduct of the manufacture of petroleum products and coal, coal tar is probably the oldest treatment for psoriasis. It reduces scaling, itching and inflammation. Exactly how it works isn't known. Coal tar has few known side effects, but it's messy, stains clothing and bedding, and has a strong odor.
Coal tar is available in over-the-counter shampoos, creams and oils. It's also available in higher concentrations by prescription. This treatment isn't recommended for women who are pregnant or breast-feeding.
Moisturizers. By themselves, moisturizing creams won't heal psoriasis, but they can reduce itching and scaling and can help combat the dryness that results from other therapies. Moisturizers in an ointment base are usually more effective than are lighter creams and lotions.
Light therapy (phototherapy)
As the name suggests, this psoriasis treatment uses natural or artificial ultraviolet light. The simplest and easiest form of phototherapy involves exposing your skin to controlled amounts of natural sunlight. Other forms of light therapy include the use of artificial ultraviolet A (UVA) or ultraviolet B (UVB) light either alone or in combination with medications.
Sunlight. Ultraviolet (UV) light is a wavelength of light in a range too short for the human eye to see. When exposed to UV rays in sunlight or artificial light, the activated T cells in the skin die. This slows skin cell turnover and reduces scaling and inflammation. Brief, daily exposures to small amounts of sunlight may improve psoriasis, but intense sun exposure can worsen symptoms and cause skin damage. Before beginning a sunlight regimen, ask your doctor about the safest way to use natural sunlight for psoriasis treatment.
UVB phototherapy. Controlled doses of UVB light from an artificial light source may improve mild to moderate psoriasis symptoms. UVB phototherapy, also called broadband UVB, can be used to treat single patches, widespread psoriasis and psoriasis that resists topical treatments. Short-term side effects may include redness, itching and dry skin. Using a moisturizer may help decrease these side effects.
Narrow band UVB therapy. A newer type of psoriasis treatment, narrow band UVB therapy may be more effective than broadband UVB treatment. It's usually administered two or three times a week until the skin improves, then maintenance may require only weekly sessions. Narrow band UVB therapy may cause more severe and longer lasting burns, however.
Photochemotherapy or psoralen plus ultraviolet A (PUVA).Photochemotherapy involves taking a light-sensitizing medication (psoralen) before exposure 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 cases of psoriasis.
Excimer laser. This form of light therapy, used for mild to moderate psoriasis, treats only the involved skin. A controlled beam of UVB light of a specific wavelength is directed to the psoriasis plaques to control scaling and inflammation. Healthy skin surrounding the patches isn't harmed. Excimer laser therapy requires fewer sessions than does traditional phototherapy because more powerful UVB light is used. Side effects can include redness and blistering.
Oral or injected medications
If you have severe psoriasis or it's resistant to other types of treatment, your doctor may prescribe oral or injected drugs. Because of severe side effects, some of these medications are used for only brief periods and may be alternated with other forms of treatment.
Retinoids. Related to vitamin A, this group of drugs may reduce the production of skin cells if you have severe psoriasis that doesn't respond to other therapies. Signs and symptoms usually return once therapy is discontinued, however. Side effects may include lip inflammation and hair loss. And because retinoids such as acitretin (Soriatane) can cause severe birth defects, women must avoid pregnancy for at least three years after taking the medication.
Methotrexate. Taken orally, methotrexate helps psoriasis by decreasing the production of skin cells and suppressing inflammation. It may also slow the progression of psoriatic arthritis in some people. Methotrexate is generally well-tolerated in low doses but may cause upset stomach, loss of appetite and fatigue. When used for long periods, it can cause a number of serious side effects, including severe liver damage and decreased production of red and white blood cells and platelets.
Cyclosporine. Cyclosporine suppresses the immune system and is similar to methotrexate in effectiveness. Like other immunosuppressant drugs, cyclosporine increases your risk of infection and other health problems, including cancer. Cyclosporine also makes you more susceptible to kidney problems and high blood pressure — the risk increases with higher dosages and long-term therapy.
Drugs that alter the immune system (biologics). Several immunomodulator drugs are approved for the treatment of moderate to severe psoriasis. They include etanercept (Enbrel), infliximab (Remicade), adalimumab (Humira) and ustekinumab (Stelara). These drugs are given by intravenous infusion, intramuscular injection or subcutaneous injection and are usually used for people who have failed to respond to traditional therapy or who have associated psoriatic arthritis. Biologics work by blocking interactions between certain immune system cells and particular inflammatory pathways. Although they're derived from natural sources rather than chemical ones, they must be used with caution because they have strong effects on the immune system and may permit life-threatening infections. In particular, people taking these treatments must be screened for tuberculosis.
Other medications.Thioguanine and hydroxyurea (Droxia, Hydrea) are medications that can be used when other drugs can't be given.
Experimental medications. There are a number of new medications currently being researched that have the potential to improve psoriasis treatment. Some of the treatments being looked at include A3 adenosine receptor agonists; anti-interleukin-17, anti-interleukin-12/23 and anti-interleukin-17 receptor agents; Janus kinase (JAK) inhibitors; and phosphodiesterase 4 inhibitors.