Medical Health Encyclopedia

It takes an average of about 25 PUVA treatments for full effect, but during that period, treatment intensity may vary:

• If there is no response after 10 treatments, the doctor may increase the UVA energy.
• If there is still no response after 15 treatments, then the psoralen dosage may be increased.
• If a patient's skin does not improve at all or worsens after these changes, then the treatment is temporarily stopped. PUVA may be causing a toxic response in such cases, and, often, the condition gradually improves over the following two weeks.
• If the skin does not improve, then PUVA treatment is considered to have failed. If skin improves during this resting period, then treatment resumes.

Maintenance Phase. Once the psoriasis has improved by about 95%, the patient may be put on a maintenance schedule. Often only one or two treatments a month are needed, but some people may need more frequent treatments. As maintenance continues and the interval between treatments lengthens, the patients may become more susceptible to tanning and sunburn. They should reduce exposure to natural sunlight during this time.

Success Rates. Nearly 90% of patients achieve marked improvement or clearing within 20 to 30 treatment sessions.

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Combinations. Effectiveness may be enhanced or response hastened by combining PUVA with oral retinoids, such as acitretin, or drugs such as calcipotriene, methotrexate, or tazarotene gel. In addition, combinations may allow for lower doses of radiation or medications to be used, minimizing side effects. Retinoids may also help protect against skin cancers. On the other hand, methotrexate may increase the risk. In some cases, patients resistant to PUVA or UVB may respond when the phototherapies are combined.

Side Effects and Complications of PUVA. Adverse side effects include the following:

• The psoralen methoxsalen causes malaise and nausea in 20% of patients. Dividing up the dose and taking it in 15-minute intervals with food or taking the herb ginger 20 minutes before taking the drug may be helpful.
• Skin reactions, including itching, sunburn, and blistering, are common. These can generally be avoided with careful administration of PUVA therapy and protective measures. Antihistamines, baths with special oatmeal preparations (Aveeno), and capsaicin (Zostrix)--an ointment prepared from the active ingredient in hot chili peppers--may be helpful.
• After treatment, white spots commonly develop where psoriasis plaques had been, particularly in people with naturally darker skin. If they are troublesome, tanning products may help darken them. Small, dark raised spots called PUVA lentigines may also develop in affected areas with long-term treatment
• Prolonged standing may trigger fainting in people with certain heart or blood pressure problems.
• People with liver disease should discuss using topical psoralens, since oral forms may have adverse effects on the liver.
• UVA penetrates the skin more deeply than UVB, so there is a greater danger of deep skin damage, accelerated skin aging, and skin cancers. Anyone who needs to avoid sunlight should not undertake this treatment.
• The procedure increases the risk for cataracts if eyes are not protected for up to 24 hours after treatment.