phototherapy in psoriasis (including a summary of NICE guidance)

Last reviewed 10/2021

Secondary care management option for psoriasis.

  • benefits of sunlight in psoriasis are well recognised
    • led to the development of phototherapy units, which emitted UV light of different wavelengths (UVA 320-400nm and UVB 290-320nm)

NICE suggest that (1):

  • phototherapy (broad- or narrow-band ultraviolet B light)
    • narrowband ultraviolet B (UVB) phototherapy should be offered to people with plaque or guttate-pattern psoriasis that cannot be controlled with topical treatments alone
    • treatment with narrowband UVB phototherapy can be given 3 or 2 times a week depending on patient preference. Tell people receiving narrowband UVB that a response may be achieved more quickly with treatment 3 times a week

  • alternative second- or third-line treatment should be offered when:
    • narrowband UVB phototherapy results in an unsatisfactory response or is poorly tolerated or
    • there is a rapid relapse following completion of treatment (rapid relapse is defined as greater than 50% of baseline disease severity within 3 months) or
    • accessing treatment is difficult for logistical reasons (for example, travel, distance, time off work or immobility) or
    • the person is at especially high risk of skin cancer

  • consider psoralen (oral or topical) with local ultraviolet A (PUVA) irradiation to treat palmoplantar pustulosis

  • when considering PUVA for psoriasis (plaque type or localised palmoplantar pustulosis) discuss with the person:
    • other treatment options
    • that any exposure is associated with an increased risk of skin cancer (squamous cell carcinoma)
    • that subsequent use of ciclosporin may increase the risk of skin cancer, particularly if they have already received more than 150 PUVA treatments
    • that risk of skin cancer is related to the number of PUVA treatments

  • do not routinely offer co-therapy with acitretin when administering PUVA

  • consider topical adjunctive therapy in people receiving phototherapy with broadband or narrowband UVB who:
    • have plaques at sites that are resistant or show an inadequate response (for example, the lower leg) to phototherapy alone, or at difficult-to-treat or highneed, covered sites (for example, flexures and the scalp), and/or
    • do not wish to take systemic drugs or in whom systemic drugs are contraindicated

  • do not routinely use phototherapy (narrowband UVB, broadband UVB or PUVA) as maintenance therapy.

UVB treatment:

Is an effective treatment method for guttate or plaque psoriasis which is resistant to topical therapy (2).

There are 2 types of UVB treatment:

  • broad band ultraviolet radiation - most effective waveband is around 290-320 nm
  • barrow band
  • spectrum of around 311nm is most effective for treatment of psoriasis - phototherapy bulbs with an output in this range have been developed and are used in narrowband UVB (nUVB) therapy
  • nUVB therapy (311-313nm) is more effective than conventional broadband UVB with respect to clearing times and remission
  • nUVB is administered three times per week (similar treatment schedule as used with broadband UVB)
  • nUVB is less erythemogenic than broadband UVB and has mainly replaced it as a treatment for psoriasis

Contraindications to UVB therapy include:

  • patients with a history of skin maliganacies
  • SLE
  • Xeroderma pigmentosum (1)

Side effects of UVB treatment:

  • acute skin burn
  • with longterm use, risk of skin malignancy (2)

nUVB in comparison to photochemotherapy (PUVA)

  • nUVB-treated patients do not have to take tablets or wear protective eyewear
  • nUVB can also be used during pregnancy and in children (2)
  • nUVB is thought to be less carcinogenic than PUVA

PUVA photochemotherapy

  • it is used in patients with severe psoriasis resistant to topical treatment and UVB
  • combination of oral or topical psoralen and subsequent irradiation with long-wave UVA light (Psoralens + UVA = PUVA)
  • oral psoralen (8-methoxypsoralen) is usually taken 2 hours prior to UVA irradiation and should be taken with a light meal in order to ensure constant and optimal drug absorption throughout a course of PUVA (2)
  • oral psoralen can cause nausea - patients must wear protective eyewear on the treatment days (24 hours from the time of psoralen ingestion) to prevent cataract formation (2)
  • topical PUVA - patients apply psoralen paint or gel to the skin or soak in a bath of psoralen solution prior to light exposure
  • remission is variable and patients will require repeat courses
  • there is a risk of nonmelanoma skin cancers associated with prolonged PUVA therapy (associated to with the number of treatments or the cumulative dose of UVA) (2)
  • PUVA therapy is often combined with other treatments such as retinoids and vitamin D analogues to reduce the number of exposures required for clearance (2)