Medical Health Encyclopedia

Some evidence suggests that by using a simple emollient (e.g., Vaseline, mineral oil) that enhanced UVB light penetration can be effective. (This increases the risk for sunburning, however, and care must be taken.)

Combinations of other topical and oral medications are being tried. For example, combining UVB with methotrexate or retinoids, such as a tazarotene gel or oral acitretin, is producing positive results. Combinations with any of these agents, however, must be supervised carefully to avoid adverse reactions.

Side Effects of UVB. The treatment can cause itching and redness. UVB radiation from sunlight is known to increase the risk for skin cancers. There is no strong evidence, however, that UVB treatments pose any risk for skin cancers except on male genitalia, which can be significant (4.5%) at high doses.

Narrow Band Ultraviolet B (NB-UVB) Radiation

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Narrow band NB-UVB radiation uses fluorescent lighting that emits radiation in a specific range between 310 and 312 nm, which, theoretically, is the most beneficial component of sunlight. Exposure times are shorter but of higher intensity than with broadband UVB.

Clearance of 75% typically occurs after 10 to 12 treatments. NB-UVB treatments performed three times a week achieve results that are equal to twice-weekly PUVA treatments. (Weekly NB-UVB treatments are not effective.) It is also probably less likely than PUVA to cause skin cancers. Studies are mixed on whether its remissions rates are equal to those of PUVA, but the weight of evidence is currently positive.

Patients prefer this approach over other PUVA treatments because they do not have to wear protective eyewear, take medications, or experience unpleasant side effects, notably nausea. It is also safe for pregnant women and children.

Some experts, then, believe that NB-UVB should be the first choice for patients with chronic plaque, with PUVA reserved for patients who fail.

According to one 2002 study, however, NB-UVB does not have any affect on the disease process itself. In the study NB-UVB radiation only affected the specific areas of skin that it targeted. Given these results, it is not clear, then, if this approach has any significant long-lasting value for treating chronic psoriasis. Combinations with topical agents, such as tazarotene or psoralens, may improve its effectiveness.

Laser Treatments

Laser UVB Treatment. A recent variation of a device called an excimer laser (Xtrac) delivers a precise UVB wavelength of 308 nm. The excimer laser is more effective than narrow-band UVB (NV-UVB) for localized psoriasis, since it allows targeting of very specific areas of skin. (It is not suitable for the scalp, however.) Generally, eight to 10 treatments administered twice a week are needed to clear psoriasis. Remission rates are similar to NB-UVB, but the excimer laser can clear the psoriasis faster and at lower doses. It also spares the healthy skin around it. Blistering is a common side effect. More comparison studies are needed to determine risk and benefits compared to NB-UVB, particularly any long-term risk for skin cancer.

Pulsed-Dye Lasers. Pulsed-dye lasers emit high-intensity yellow light, which destroy the tiny blood vessels that make up psoriatic plaques. (This treatment has been used for years to remove birthmarks, such as port wine stains, and unsightly blood vessels on the skin.) Some studies have reported significant (but not complete) improvement and remissions that have lasted up to 13 months. Treatments last up to 30 minutes and can feel uncomfortable (similar to being repeatedly snapped with a rubber band). It typically takes up to six sessions to clear the target areas. Bruising is common and there is a small risk for scarring.

Commercial Tanning Units

Home tanning devices and tanning salons are not ordinarily recommended, but they may be helpful for patients without access to a medical unit. In a 2003 study, many patients achieved a significant reduction in symptoms with a combination of acitretin and exposure to a UV-B commercial tanning unit (A Wolff tanning bed). However, UV outputs can vary widely among tanning beds and salons. Some units emit UVA radiation, which poses a higher risk for skin cancers. Adverse effects of tanning salons that use UVA or UVB radiation are the same as with any UV phototherapies, including a risk for skin cancer.