Psoralen plus exposure to UVA light is sometimes used to treat alopecia areata

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  Psoralen Plus Ultraviolet A Radiation (PUVA) for Alopecia Areata

Psoralen Plus Ultraviolet A Radiation or PUVA has been used in alopecia areata treatment since 1974. PUVA is a photo chemotherapy that involves a topical or oral application of psoralen plus followed by a measured dose of ultraviolet radiation. Psoralen plus is a drug, which in its natural state is found in many plants. It contains a chemical 8-methoxypsoralen or 8 MOP, which is sensitive to ultraviolet rays. It enhances the effect of the ultraviolet rays on the skin by making the skin photosensitive. Psoralen has been known since ancient times as a cure for skin diseases.

Prior to its application in alopecia areata PUVA was used for treating skin disorders such as psoriasis, vitiligo, atopic dermatitis and pruritis or itching. PUVA therapy has shown the following effects:

  • It depresses the number of circulating E rosette forming cells in psoriatic patients and controls.
  • It reduces the fraction of circulating helper T-cells in psoriatic patients.
  • It induces suppressor T cells in mice.
  • It may prevent attack on the hair follicles by the immune system by depleting the number of Langerhan’s cells.
  • It has been to known to stimulate the dopa negative melanocytes in the outer root sheath to divide and multiply.

By its photo immunologic effect on T cells, PUVA may be a good alopecia areata therapy. The last two effects may also make PUVA an effective treatment for alopecia areata. Increasing evidence indicates an important role of melanocytes in alopecia areata. Studies have shown that oral applications were more effective than topical applications, perhaps, due to some kind of change in the immune system.

A typical PUVA session consists of, firstly, an oral or topical administration of psoralen plus and two hours later, irradiation to UVA rays. UVA is a broad spectrum, high intensity artificially sourced radiation. As the situation demands, the irradiation could be on the whole body or restricted to the area affected by hair loss. The source of UVA is a square or hexagonal light box, fitted with fluorescent tubes, emitting these UVA rays. The duration of each session is progressively and gradually increased.

Response Rate to PUVA

In practice, PUVA has shown mixed success in several studies. Under uncontrolled conditions, cosmetically acceptable hair growth was observed in 40% to 50% of the patients. Since studies were uncontrolled it was difficult to find out how much was genuine growth and how much spontaneous remission. One significant finding of these studies was the high relapse rate of 30% to 40% cases when PUVA treatment was discontinued. The reason for such high relapse rates is not known, the current belief being that the new hair growth prevents the UVA rays penetrating the skin. Technical improvements such as comb emitting UVA failed to show any significantly better response.

A five-year study on PUVA treatment was conducted on 23 patients. Out of these 23 patients, seven had patchy alopecia, thirteen had alopecia totalis and three had alopecia universalis. Irradiation was done in a stand-up light box with fluorescent tubes emitting radiation of 320 to 400nm strength. Twenty patients were orally administered 8-MOP two hours before irradiation. Out of these 20 patients, 17 were given total body UVA and three were given scalp-only treatment. The dosage ranged from 10mg for patients weighing less than 25kgs, to 60mg for those weighing more than 90kgs. Three alopecia totalis patients were given 0.1% 8 MOP application and scalp-only irradiation. Irradiation was given three times a week and was gradually increased with each session. Vellus hair growth was observed at the 30th session and complete hair growth was seen between the 50th and the 80th sessions. Of the 17 given an oral application and total body irradiation, 11 showed 90% or more hair growth. Complete hair regrowth was observed in:

  • 4 of 7 patients with patchy alopecia
  • 5 of 7 patients with alopecia totalis
  • 2 of 7 patients with alopecia universalis

The three who received topical application and scalp only UVA exposure were failed treatments and the three who received an oral application and scalp only irradiation reported partial response. Nausea was the most observed side effect affecting 30% of patients given oral application of eight MOP. No definite conclusions were possible from this study.

In another study, conducted along largely similar lines on 30 patients, the response of five patients with alopecia totalis and the rest with patchy alopecia was observed. After treatment for 7 to 9.4 months, one patient showed excellent response, 8, of which 3 were alopecia totalis patient, showed good results, seven gave poor results and 10 were treatment failures. All those who showed good results, had a relapse within a mean time of 7.7 months after the end of treatment.

Several such studies showed that there was no significant difference in response between patients having different types of alopecia areata.

Taylor and Hawke reporting on their 10-year study on PUVA, mention that the response rate – taken as more than 90% regrowth – was 43% in patchy alopecia and 50% in alopecia totalis and alopecia universalis. However, if cases of vellus hair growth and relapse after 4 months of treatment were excluded, the response rate was an unsatisfactory 6.3% for patchy alopecia and 12.5% for alopecia totalis and universalis. Not surprisingly, they concluded that PUVA was not a very effective long-term treatment for alopecia areata.

Side Effects of PUVA

Due to UVA irradiation, side effect posing the greatest risk to PUVA patients is the threat of various types of skin cancer, especially, potentially fatal melanoma. Therefore, post treatment monitoring of PUVA patients is essential. These patients should immediately contact doctors in case of skin abnormalities like unusual coloring, pain or itches. Nausea is the most prominent side effect reported. Other minor side effects include:

  • Sunburns called photoxic erythema
  • Headache and dizziness
  • Redness of the skin
  • Skin darkening
  • Skin ageing
  • Itching


The risk of cancer makes PUVA unsuitable for long-term therapy. Even otherwise, due to other factors, especially, high relapse rates; several studies have cast a doubt on their long-term efficacy. However, PUVA may have a role in alopecia areata management. Narrow band UFB may be a better alternative, once research on it is complete.

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