Psoralen Family information.
Psoralen and UVA light therapy (PUVA) for psoriasis
Examples
Psoralens
Pills, lotions, or bath salts
methoxsalen
A psoralen medication is taken 1 1/2 to 2 hours before you are exposed to ultraviolet A (UVA) light (PUVA). This treatment is repeated 2 to 3 times a week. The dose of medication is not increased, but the amount of light may be increased.
Goggles should be worn to protect eyes during UVA treatment. Special UVA-blocking glasses should be worn for 24 hours after PUVA therapy. Men should protect their genitals from UVA exposure during treatments.
Psoralens may also be used in a form that can be put into your bath water. This form causes greater sensitivity to UVA than the oral medication, so lower doses of UVA can be used.
How It Works
Psoralens increase the skin's sensitivity to UV light, including sunlight. They are used to improve the effectiveness of UV light therapy for psoriasis.
It is thought that PUVA therapy reduces the excess growth of skin cells. It also weakens the immune system.
Why It Is Used
PUVA is used to treat moderate to severe psoriasis (covering more than 20% of the skin).
PUVA is used to treat psoriasis that has not responded to creams, ointments, or tar products used with UV exposure (phototherapy). It should be used in the lowest doses possible. Higher doses and more exposure increase the risk of skin cancer.
Psoralens should not be used by:
Children under age 12, because the UV light therapy may cause cataracts.
People who have diseases that make their skin more sensitive to sunlight (such as lupus).
Fertile men and women who do not use birth control. There is a small risk of birth defects.
Pregnant women, because of possible effects on developing fetuses. How Well It Works
Many studies have shown that PUVA is effective in treating psoriasis.1
In most cases, the skin clears after 20 to 30 treatments.
Side Effects
Short-term side effects when using PUVA to treat psoriasis include:
Skin redness, headache, nausea, itching.
Burns.
The spread of psoriasis to skin that was not affected before (Koebner's response).
Nausea from the medication. The most significant potential long-term effect of PUVA treatment is squamous cell carcinoma, a type of skin cancer. PUVA treatments with cyclosporine have shown a significant increase in the risk of squamous cell cancer.2
The male genitals are highly susceptible to the cancer-causing effects of both PUVA and UVB therapy. High levels of exposure to UVB carry a higher risk of genital cancers than low levels. Female genitals do not seem to be affected.
Other long-term side effects when using PUVA to treat psoriasis include:
Premature skin damage associated with sun exposure.
Discolored spots on the skin.
Overgrowth of the scaly layer of skin caused by exposure to sunlight (actinic keratosis).
Nonmelanoma skin cancer.
Cataracts. Cataracts may be avoided by wearing sunglasses that block UV light when outdoors. See Drug Reference for a full list of side effects. (Drug Reference is not available in all systems.)
What to Think About
Psoralens applied to the skin (topical) may help to avoid some side effects of PUVA. They may be especially helpful when psoralens taken by mouth (oral) causes severe nausea. Topical psoralens may be used for psoriasis that affects only a small part of the skin.
Topical psoralens, such as those given in bath water, are as effective as oral psoralens. However, if light treatments are given in a doctor's office, they may be less convenient.
See a list of questions to ask your doctor about medications.
Author: Kerry V. Cooke
Kathleen M. Ariss, MS
Last Updated February 28, 2002
Medical Review: Adam Husney, MD - Family Practice
Randall D. Burr, MD - Dermatology
© 1995-2003, Healthwise, Incorporated, P.O. Box 1989, Boise, ID 83701. ALL RIGHTS RESERVED.
Additional:
**As far as I understand it,(psoralens)...although some may vary in strength, they are basically all the same, and are just used under different brand names.
Drugs known as psoralens cause the skin to be excessively sensitive to sunlight. Psoralens include Oxsoralen (methoxsalen or 8-MOP) and Trisoralen (trioxsalen). In addition, some antibiotics such as ciprofloxacin and tetracycline may make the skin more likely to sunburn. If St. John?s wort, which also sensitizes the skin to light, is taken at the same time as another of these sun-sensitizing drugs, the chance of sunburn increases.