Medical Treatment of Psoriasis
No cure for psoriasis exists, but a number of good treatment options are available to control the skin lesions. Since this disease is incurable, psoriasis control must be considered for the long-term. The spectrum of treatment options depends on the extent and severity of the disease: topical agents (drugs applied to the skin), phototherapy (controlled exposure to ultraviolet light), and systemic agents (orally or percutaneously administered agents). All of these treatments may be used alone or in combination with one another. Psoriasis in children younger than age 15 is extremely rare; therefore, the following treatments are confined to adult use.
Topical agents: Medications applied directly to the psoriatic skin lesions are the safest approaches to treatment but is only practical if treating localized disease. The main topical treatments are corticosteroids (in vehicles such as foams, creams, gels, liquids, sprays, or ointments), vitamin D-3 derivatives, coal tar, anthralin, or retinoids (vitamin A analogs). There isn't one topical drug that is best for all people with psoriasis. Because each drug has adverse effects or becomes less effective over time, it is common to rotate them. Sometimes topical preparations are combined together. For example, keratolytics (substances used to break down scales or excess skin cells) are often added to these preparations. Some preparations should never be mixed together because they interfere with each other. For example, salicylic acid inactivates calcipotriene cream or ointment (a form of vitamin D-3). On the other hand, drugs such as anthralin (tree bark extract) may require addition of salicylic acid to work effectively.
Phototherapy (light therapy): Ultraviolet (UV) light, a portion of the sunlight spectrum with wavelengths between 290-400 nm, can have beneficial effects on psoriatic skin presumably by altering certain immune functions. Disease considered too extensive to be treated by topical approaches is usually greater than 5%-10% of the total body surface area is an appropriate indication for this sort of treatment. Resistance to topical treatment is another indication for light therapy. Although normal sunlight contains these wavelengths, self-exposure to sunlight must be done in under controlled conditions to minimize the potential problems. In a physician's office, proper facilities are required to administer the two main forms of light therapy. Medical light sources use special wavelengths of light and timers to assure the correct dosage of light. Sunlamps and tanning booths are usually not acceptable substitutes for medical light sources.
Systemic agents (drugs taken within the body): These drugs are started only after both topical treatment and phototherapy have been carefully considered. Certain systemic agents are also very effective in controlling psoriatic arthritis. People whose disease is disabling because of physical, psychological, social, or economic reasons may also be considered for systemic treatment.
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