Psoriasis Patient Information Fact Sheet
How is psoriasis treated?
Natural sunlight seems to be of benefit in many psoriasis sufferers. However, the greater the exposure to sun, the greater the risk of developing skin cancer, so the amount of exposure to sunlight needs to be monitored carefully such that the risks do not outweigh the benefits. Sun lamps also have the potential to be harmful to skin and should be used only under the direction of your doctor.
Professional treatment may be available in the form of PUVA. This treatment involves the administration of a compound known as a psoralen, such as methoxsalen (either orally by mouth [8-MOP, Oxsoralen-Ultra] or applied topically to the skin [Oxsoralen]) followed two hours later by exposure to long-wave ultraviolet light (UVA) for 15 to 30 minutes. This treatment is repeated two or three times a week and in most people the psoriasis is cleared in four to six weeks. Although this treatment has been popular in the past, there are still risks associated with the future development of skin cancer and its use needs to be carefully supervised.
There are many topical products available for treating psoriasis: Anthralin (Zithranol-RR) is available as a cream and is sometimes used in combination with another medication such as salicylic acid. Anthralin is known to be a potential skin irritant. The irritant potential of anthralin is directly related to the strength being used, the time of contact, and each patient's individual tolerance. Where the response to anthralin treatment has not previously been established, treatment is usually started using a short contact time (5–15 minutes) for at least 1 week. When a short contact time is used initially, it can be increased stepwise to 30 minutes before removing the cream by washing or showering. The optimal period of contact will vary according to the patient's response to treatment. Apply sparingly to the psoriatic lesions avoiding normal skin and rub gently and carefully into the skin. Avoid applying an excessive quantity which may cause unnecessary soiling and staining of the clothing and/or bed linen. At the end of each period of treatment, rinse the skin thoroughly with cool to lukewarm water before washing with soap. The margins of the lesions may gradually become stained purple/brown as treatment progresses, but this will disappear after cessation of treatment.
Tar products such as coal tar (Scytera) may be used on areas where anthralin is unsuitable as they tend to be less irritating. Although the smell, color and staining properties of coal tar make it undesirable, it does not have any significant side effects and the effects are usually long-lasting.
Topical corticosteroids (eg, creams, gels and ointments) are useful for treating small areas of psoriasis but long-term use, particularly in large doses, is not advisable because of the potential side effects. Topical corticosteroids are often prescribed as first-line treatment because they are so easy to use. Once-daily application is usually sufficient. Examples of topical steroids include betamethasone (Diprolene, Luxiq), clobetasol propionate (Clobex, Olux, Temovate), hydrocortisone and mometasone (Elocon).