Introduction

Ultraviolet (UV) phototherapy is used for a myriad of dermatologic conditions such as psoriasis and mycosis fungoides (MF). UV phototherapy is most commonly administered in an office setting, with ideal treatment typically consisting of several sessions per week.

While phototherapy is effective for many conditions, the time and expense of this treatment can be a burden and an obstacle [1]. Many patients live over one hundred miles from a dermatologist or have other time and resource limitations that make in-office phototherapy inaccessible. Therefore, in-office phototherapy may not be a pragmatic treatment option for many patients who could potentially benefit from it.

Unsupervised sun exposure is a standard recommendation when in-office phototherapy is not feasible [2]. Commercial tanning facilities may offer another potential alternative means to access phototherapy, being both conveniently located and economically feasible. This can provide access to phototherapy to many patients who currently find treatment with in-office phototherapy to be cumbersome or impracticable. We examined available evidence for the use of commercial tanning facilities as a dermatologic treatment modality in diseases such as atopic dermatitis, acne, hand eczema, MF, vitiligo, and pruritus.

Methods

Literature searches were done in PubMed in February 2015 combining therapy descriptor keywords, such as “tanning beds” and “phototherapy”, with dermatologic conditions known or believed to be sensitive to UV light, including “psoriasis”, “mycosis fungoides”, “acne”, and “atopic dermatitis”/“eczema”. No inclusion or exclusion dates were defined. From there, further articles were found using the reference sections of the initial papers. A similar methodology was used with the Google Scholar search engine. Additional information was sought with targeted searches in both PubMed and Google Scholar. In conditions that did not have studies using commercial tanning beds, we investigated the efficacy of UV radiation overlapping with the emission spectrum of tanning beds. Only articles in English and prospective studies were included in this review. This article is based on previously conducted studies and does not involve any new studies of human or animal subjects performed by any of the authors.

Results

Characteristics of Indoor Tanning Light

The light used during indoor tanning is poorly defined. The US Food and Drug Administration does not specify limits on the power of UV light emissions, instead defining “irradiance ratio limits”, where the ratio of irradiance between wavelengths of 200 and 260 nm to the irradiance between wavelengths 260 and 320 nm should not exceed 0.003 at any distance and direction from the source [3]. While in the US there are state and federal regulations, according to a study performed in North Carolina, the extent to which commercial tanning facilities comply is poor, with only 1 out of 32 commercial tanning establishments within complete compliance of state and federal guidelines [4].

The wavelengths of UVA and UVB irradiation from tanning beds are highly variable; however, tanning beds as a whole tend to emit primarily UVA irradiation. Rates of UVB emissions range from 0.5% to 5.0% in North Carolina tanning beds [4]. Another study of North Carolina tanning beds found a wide range of UVA irradiance, 17.7–674.0 W/m2 and a UVB range of 0.12–0.82 W/m2 (2.11–14.00 minimal erythemal dose/h) [5].

Tanning beds analyzed in the UK between 2004 and 2005 showed tremendous variability in spectral distribution of UV output, resulting in the average erythemal irradiance ranging from 0.02–0.93 W/m2, with an average of 0.41 W/m2 [6]. In a study conducted in 2008, 78 indoor tanning facilities from 6 regions throughout Norway were characterized [7]. The average UVB irradiance was 0.194 W/m2 erythema-weighted dose (range 0.059–0.489 W/m2), and the average UVA irradiance was 0.156 W/m2 erythema-weighted dose (range 0.079–0.568 W/m2). Norway regulates indoor tanning facilities, with both short-wave and long-wave UV irradiance limits set at 0.15 W/m2. Only 23.3% of tanning facilities were in compliance with maximal irradiances for both UVA and UVB spectra. Ninety-six percent of tanning bed devices were approved models, but only 74% of lamps in these tanning beds were an approved type. The maximum erythema-weighted UV irradiance varied by up to a factor of 2 for the same tanning bed devices in different facilities, due to the difference in lamps used. Additionally, within each facility, irradiance measures varied by up to a factor of two, due to the different tanning bed devices [7]. The variety of tanning bed devices and lack of standardization of lamps within these devices present a therapeutic hurdle to recommending their use as a treatment for skin disease.

Efficacy of Tanning Beds

While different tanning beds emit variable amounts of UVB and UVA (varying in both the absolute flux and the ratio of UVB to UVA), there is extensive in vitro evidence that both UVA and UVB have anti-inflammatory effects (Tables 1, 2).

Table 1 Summary of the known anti-inflammatory mechanisms of UV light
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Table 2 Summary of evidence supporting commercial tanning beds or UV light in the treatment of selected dermatologic conditions graded on the basis of level of evidence by using the Scottish Intercollegiate Guidelines Networks grading recommendations
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Risks of Tanning

As with any UV light-based therapies, there are potential risks of using tanning beds as treatment (Table 3). There is a link between artificial UV light exposure and an increased risk of developing skin cancer. In 2006, a meta-analysis showed an increased risk of developing melanoma, squamous cell carcinoma (SCC), and basal cell carcinoma (BCC) in patients who have ever used a tanning bed compared with those who have never tanned with artificial UV light [8]. A particularly large increase in melanoma risk was found when comparing those who ever tanned before age 35 years to those who had never used an indoor tanning device. A subsequent study found a dose/response relationship between artificial UV light exposure and increasing risk of melanoma, with those having tanned 10 times or fewer having only a 34% increased risk of developing a melanoma, compared to 272% in those patients who have used indoor tanning beds over 100 times [9]. In a more recent study, an association was found between age of first tanning bed exposure and increased risk of melanoma in patients with more than 10 tanning bed exposures [10]. A large prospective study found no association between age range of most frequent tanning bed use and risk of melanoma or SCC, but did find an even greater risk of BCC in women who visited tanning beds most frequently during their high school and college years compared to those who visited most frequently during age 25–35 years, both of which were greater than the risk in women who had never used a tanning bed [11]. This was further supported by findings that a dose/response relationship can be found between the risk of developing a BCC and increasing numbers of tanning sessions, hours spent indoor tanning, years spent indoor tanning, number of burns at the biopsy site, and number of burns associated with indoor tanning [12]. This study also found a strong relationship with artificial UV light exposure and truncal BCCs, as compared to the head and neck, indicating a possible increases susceptibility of bodily areas that receive less incidental solar irradiation [12]. Furthermore, the World Health Organization characterizes tanning beds as carcinogenic to humans, therefore, caution should be exercised in recommending tanning beds for treatment, especially in those who are at risk for developing melanoma or other skin cancers [13]. While there is strong evidence supporting association of tanning bed use and the increased risk of skin cancer, some of this association may not be causal in nature.

Table 3 Risks and side effects associated with excess ultraviolet light exposure [73]
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Tanning and Conditions Treated by Phototherapy

Psoriasis

Assessing the evidence for commercial tanning facilities as a treatment for psoriasis is important as indoor tanning is already commonly used by people as a psoriasis treatment, perhaps the most frequently used form of phototherapy for psoriasis. One center reported that more than 50% of patients presenting to their clinic had tried or were currently treating their psoriasis with commercial tanning sessions [14]. Another survey found that 36% of patients reported having tried commercial tanning beds as a psoriasis treatment [15].

There may be concern that tanning beds that emit primarily UVA would not be effective for the treatment of psoriasis. While one study found that UVA doses up to 30 J/cm2 were ineffective for psoriasis, Parrish [16] found that psoriatic plaques are responsive to erythemogenic doses of either UVA or UVB light [16, 17]. The ability of tanning beds to treat psoriasis was compared on the basis of their UVB output, one with a UVB output of 4.6% was compared to another with a lower UVB output (0.7%) in a within-patient comparison technique [18]. There were marked and equivalent improvements in Psoriasis Area Severity Index (PASI) scores from baseline in patients treated unilaterally with either lamp with 12 exposures to an equal erythemal dose over a 4-week period. While exposure to either UVA or UVB light can induce clearance of psoriatic plaques, UVA requires more energy (time × power) to reach erythemogenic dosing [16].

The ability of a specific tanning bed using the Bellarium S lamp (a commonly used tanning bulb) to clear psoriatic plaques was tested in a clinical trial [19]. Twenty patients with psoriasis vulgaris were treated with three to five tanning bed sessions per week for a 6-week period. Sixteen patients had improvement in their disease as measured by PASI and 17 patients as measured by the self-administered PASI (SAPASI). The average reduction in the PASI and SAPASI was 35.4% and 36.2%, respectively, for all enrolled patients and 39.4% and 52.3%, respectively, in those completing the 6-week study. A clear dose response was observed, with greater cumulative UV exposure associated with greater disease improvement. The magnitude of PASI reduction was modest compared to recent studies of biologics, but the authors commented that the improvement was comparable to PASI reductions reported in patients treated with betamethasone valerate, calcipotriol, dithranol, and etretinate [20, 21]. Short-term side effects were minimal, including mild phototoxic reactions in seven patients and itching in three patients [15]. Long-term risks, however, were not assessed. Overall, this study demonstrated the efficacy and feasibility of using commercial tanning beds in the treatment of psoriasis, but as the tanning bed treatments were administered in a well-monitored medical setting, the findings may not fully extrapolate to tanning in the community setting.

A study assessing the effectiveness of a UVA light-dominant commercial tanning unit compared to visible light using each patient as their own control demonstrated a slight, but significant improvement in the PASI score, with the difference coming from an improvement in the erythema component of the PASI score [22].

One of the most effective treatments for psoriasis is the combination of phototherapy and oral retinoids [23]. Acitretin and tanning bed UV exposure combination therapy has been studied and is more effective than tanning alone, with 83% of patients achieving clearance or near clearance in a retrospective review, and PASI scores demonstrating an average reduction of 79% from baseline in a prospective open-label trial of 17 patients [24]. Not only did many patients clear or experience near clearing of the psoriasis, but in both the retrospective review and prospective trial, several patients were able to remain clear after stopping acitretin and only using two maintenance tanning bed light treatments per week. This illustrates the potential for tanning bed treatments as the only maintenance therapy for patients who are currently clear of their psoriasis [24].

Home UVB therapy is also a convenient option for patients with psoriasis, although not all patients have access to it. One randomized, controlled study comparing home UVB to outpatient administered UVB treatment demonstrated similar efficacy to that of outpatient UVB therapy [25]. In this study, median PASI scores decreased for patients receiving home phototherapy 74%, respectively, compared to a 70% decrease in the outpatient phototherapy group.

Acne

Various light source therapies are either currently used or under investigation for the treatment of acne vulgaris, mainly pulsed dye laser or photodynamic therapy [26–28]. While the evidence for the use of tanning beds to treat acne is limited, in a study of Swedish tanning bed users, 34% believed that sunbathing in natural light improved acne versus only 11% of non-users, which suggests a potential use of tanning beds as a possible adjuvant treatment for acne [29]. However, we did not identify any clinical trial supporting the use of tanning bed UV light in the treatment of acne vulgaris.

Atopic Dermatitis

The prevalence of therapeutic use of tanning beds in patients with atopic dermatitis has been reported to be 66% [29]. This is not unexpected as narrow band (NB) UVA1, medium-dose UVA1, and combination UVA/UVB irradiation have been successfully employed as treatments for atopic dermatitis [30–32].

Daily exposure to high-dose UVA1 (130 J/cm2) resulted in significant improvement of study subjects’ atopic dermatitis [21]. UVA1 (60 J/cm2) is equally effective compared to topical tacrolimus in treating atopic dermatitis [33]. UVA/UVB treatment was also effective at reducing clinical score [34]. NB-UVB as monotherapy is also effective in treating atopic dermatitis [35]. To our knowledge, no studies have been done investigating the use of tanning beds in atopic dermatitis, however, the range of UV light sources demonstrated to be effective in the treatment of atopic dermatitis suggests that the use of tanning beds as a treatment for atopic dermatitis may be efficacious.

Hand Eczema

Psoralen UVA (PUVA) is highly effective in the treatment of hand eczema [36, 37]. In an open-label randomized controlled trial comparing two established protocols, oral methoxsalen UVA treatments three times per week at home with a portable facial tanning unit were found to be as effective as inpatient, biweekly trioxsalen bath UVA treatments [38]. A 9 mW/cm2 (90 W/m2) UVA facial tanning unit was used; the power output of this device is far below the average of 192.1 W/m2 found in the North Carolina tanning bed study. Due to commercial tanning beds having primarily UVA irradiation, use of tanning beds with psoralen may have a place in the out of office treatment of chronic hand eczema, however, care must be taken because of the risks of severe burns. Concurrent use of tanning beds and psoralen may be potentially used in hand eczema due to the low body surface area involved, as patients would only need to expose their hands to the tanning bed radiation. The application of psoralen to extensive areas or systemic psoralen should not be used with tanning beds, as the risks of burns may be life threatening in these patients.

Cutaneous T Cell Lymphoma

Various phototherapeutic modalities are currently used for MF. Treatment with NB-UVB is effective for MF, leading to complete remission in the majority of patients [39]. The efficacy of five times weekly UVA1 phototherapy for the treatment of MF was also investigated [40]. After 3 initial treatment sessions with standardized doses of 10, 20, and 40 J/cm2, symptoms were used to determine future dosing, with all 4 patients clearing with maximum doses of 120 J/cm2 UVA1 and 3 out of 4 clearing with maximum doses of 80 J/cm2. With minimal erythemal dosing of UVA light noted to be 10–100 J/cm2 [16] commercial tanning beds could be used to deliver therapeutic doses of UVA light in the treatment of cutaneous T cell lymphoma, though we found no reported cases of this therapeutic approach.

Vitiligo

Many UV-based therapies are employed when treating vitiligo, including PUVA, NB-UVB (both in office and home units) and excimer laser, along with adjuvant treatments such as topical calcineurin inhibitors and topical corticosteroids [41–44]. One study found that broadband UVB phototherapy was superior to NB-UVB in treating vitiligo, which suggests that tanning beds would also be effective [45]. Sun exposure induces repigmentation of vitiligo lesions during the summer in many patients [46]. While there is a possibility of using commercial tanning beds to deliver therapeutic doses of UV light to patients with vitiligo, we did not find clinical trials assessing this potential use.

Pruritus

The pathophysiology of itch is still being elucidated, and the mechanism by which UV light reduces pruritus is not well defined. Given the relative lack of penetration of UVB through the epidermis, the effect of UVB is thought to be through its action on epidermal keratinocytes and Langerhans cells. The effects of UVA light are generally believed to be dermal in origin, affecting lymphocytes, mast cells, and fibroblasts [47]. Dermal Schwann cells and perineural cells degenerate after exposure to UVA light as well [48].

UVB light has been successfully employed in the treatment of uremic pruritus for decades. Early studies demonstrated the efficacy of broadband UVB, with 9 out of 10 patients experiencing a significant reduction in pruritus [49]. NB-UVB is also effective [50, 51]. There are several theories on the mechanism of UVB light in the treatment of uremic pruritus, including UVB-induced reduction in skin phosphorus, leading to decreased microprecipitation of divalent cations with phosphorous in the skin and UVB-induced mast cell apoptosis [52, 53]. There may be a systemic effect of UV on uremic itch, as patients treated unilaterally with UVB light report a reduction in pruritus on both sides of their body [54].

HIV pruritus can be treated with either UVB or PUVA [55, 56]. And while in vitro and animal studies on the safety of UV light therapy raise concerns about induction of viral replication, these safety concerns have not shown up in vivo, and reviews of the literature have endorsed UV light therapy as safe in this setting [57, 58]. However, we found no data on the potential use of commercial tanning beds in the treatment of HIV-associated pruritus.

Discussion

Many skin conditions are responsive to office phototherapy, however, office phototherapy can be expensive and inconvenient. Home UVB therapy is a potential alternative. When phototherapy is desired and office and home UVB treatments are not feasible, indoor tanning may be of benefit. There are certainly limitations to this approach—imprecise outputs of the lamps and beds, imprecise spectral targeting of commercial tanning beds, administration by the patient or non-medical staff, acute and long-term side effects—but there are limitations to all treatment options. Due to the significant risks of tanning beds and the potential variability in dosing, practitioners should exercise their clinical judgment in recommending it to their patients. While some patients may benefit, others may have significant risk factors, such as a predisposition to skin cancer, that would need to be taken into account (along with the risks of other treatments and the risk of suffering with no treatment) when recommending treatment options.

A significant concern for use of commercial tanning facilities in phototherapy is their considerable variability in emission make up and dosing. Variability in exposure can be reduced by selecting a single bed, with additional caution/dose reduction when bulbs are changed; doing so may provide more predictable dosimetry than is obtainable with sun exposure. For psoriasis treatment, 3–5 sessions per week for 6 weeks with 4.6% UVB tanning lamps was effective (Table 4) [19]. The length of the sessions was based upon self-reported skin type and the manufacturer’s suggestions for the particular bulb used in that study. For patients on an oral retinoid, a starting dose of 2–3 min with 1 min incremental increases (30 min maximum), 5–7 times a week was safe in a single study that used a 4.7% UVB output commercial tanning unit (Table 5) [24]. Because of the variability between different tanning beds, these data can give only a limited reference point for dosing; starting with a low dose and increasing slowly as tolerated would be prudent.

Table 4 Fleischer et al. [19] exposure schedule for the use of tanning beds for psoriasis treatment
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Table 5 Suggestion for a regimen for using commercial tanning beds as a dermatologic treatment
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Given the variability demonstrated in the UV output of indoor tanning devices, we recommend some practical safety tips (Table 5). Patients should keep treatment time the same if they have asymptomatic pinkness or erythema of the skin and should be aware side effects such as pain and/or blisters. Patients with lighter skin types should exercise more care as they are more susceptible to burns from tanning compared to darker skinned individuals. After about six times per week for 1 month, reassess for response to treatment. This approach maximizes safety and allows for increasing doses as tolerated.

This study is limited by the lack of double-blind, placebo-controlled trials, long-term follow-up studies and meta-analyses for tanning facility use in dermatologic phototherapy, and by the lack of standardization of both tanning facilities and exposure dosing. Furthermore, much of what is extrapolated for the efficacy of tanning beds is through methods which emit UV therapy that overlaps with the UV emissions of tanning beds.

Commercial tanning beds have been successfully used as a treatment modality for patients with psoriasis, and show promise for the treatment of many other dermatoses (Table 2). The evidence for the use of commercial tanning, with its clear dose–response effect [18], is as strong as or stronger than for sun exposure, which lacks demonstration of a dose–response effect [59]. Moreover, dosimetry can be better controlled with the use of indoor tanning when compared to exposure to natural sunlight, which can vary greatly based on geographical location, weather conditions, and the time of day and year [59]. The National Psoriasis Foundation [2] recommends natural sunlight as a potential treatment for psoriasis. Considering this, recommending the use of tanning beds as a potential treatment may be just as reasonable.

Conclusions

While the use of tanning beds may not be right for every patient, in some patients the benefits of tanning beds as a source of UV therapy for their dermatological disease may be beneficial. Whether physicians recommend commercial tanning bed use or not, patients are likely to try it. In one study, nearly a third of male patients with psoriasis and nearly half of female patients with psoriasis reported having tried tanning as a treatment [15]. Withholding information on how to best use tanning may not be in our patients’ best interest. While tanning beds carry the possibility for significant side effects, their benefits and risks should be weighted just as with any treatment or medication. Furthermore, the risks of treatments that would be used as an alternative to tanning beds should also be considered, as many medications, such as methotrexate, carry the risk of severe side effects. Although there are significant risks associated with tanning beds, completely discounting its use may be a disservice to patients who have poor access to in-office and home phototherapy.