Solar Urticaria Treatment & Management

Updated: Apr 18, 2017
  • Author: Marc Zachary Handler, MD; Chief Editor: Dirk M Elston, MD  more...
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Treatment

Approach Considerations

Treatment of solar urticaria can be frustrating. A combination of different modalities is often necessary, but the success of these methods is highly variable. Taking measures to avoid or minimize sun exposure is the most important step for patients with solar urticaria. Unfortunately, this often requires major adjustments in lifestyle, which might be impractical for some patients.

Long-acting, nonsedating H1-receptor blockers are the first line of treatment for solar urticaria. This is because the disease involves IgE-mediated mast cell degranulation with consequent histamine release.

Phototherapy with UV-A, [9] broadband UV-B, or narrowband UV-B or photochemotherapy with oral methoxsalen (8-MOP, a form of psoralen) plus UV-A is also effective for treating solar urticaria.

In rare systemic cases of the disease, supportive medical measures to maintain blood pressure and adequate ventilation may be required if extensive cutaneous surfaces are simultaneously involved.

One case report described two cases of idiopathic solar urticaria treated with intravenous (IV) immunoglobulin, with durable remissions of 13 months and 4 years. Treatment was with 2 g/kg over several 5-day courses approximately 1 month apart. [10] Another case report also described successful treatment of solar urticaria with IV immunoglobulin and suggested that it be discussed as a therapeutic option if high-dose antihistamines provide unsatisfactory results. [11, 12]

Omalizumab, an anti-IgE antibody approved for use for chronic spontaneous urticaria, has been reported to be effective in the treatment of solar urticaria. [13, 14, 18] Use of the medication for solar urticaria is currently off-label. A small, single-arm, French study administered 300-mg subcutaneous doses of omalizumab every 4 weeks for three total visits; despite some improvement, results were lackluster. [15]

Plasma exchange therapy has been effective in a few cases, especially in patients with a circulating factor in their serum demonstrated by a positive intradermal test finding. [16] However, therapy has been reported to be ineffective in some centers. Until definitive studies are conducted to evaluate the efficacy of this therapy, it should be reserved as a last resort.

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Antihistamines

The success of antihistamine therapy depends on disease severity. For example, antihistamine monotherapy would probably not benefit someone who develops hives after just a few seconds of sun exposure, but it would help a patient who requires at least 10 minutes’ sun exposure before hives appear.

Antihistamines seem to block wheal response and minimize pruritus, but they do not entirely eliminate an erythematous reaction. This should be explained to the patient.

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Phototherapy and Photochemotherapy

As previously mentioned, phototherapy with UV-A, [9] broadband UV-B, or narrowband UV-B or photochemotherapy with the psoralen agent oral methoxsalen (8-MOP) plus UV-A is effective for treating solar urticaria. Desensitization treatments are usually performed in the spring. Unfortunately, the tolerance induced by these modalities is often short-lived, and maintenance therapy is needed. [17]

Psoralen–UV-A, or PUVA, can cause disease improvement or remission lasting several months. Based on available evidence, it is probably the treatment of choice for patients not sufficiently helped by antihistamines.

A number of treatment protocols are used for the different light sources mentioned, but the optimal protocol has not been clearly established.

Minimum urticarial dose

The minimum urticarial dose (MUD) with the specific light box being used in the treatment of solar urticaria must be determined. The MUD is repeated during the course of treatment in order to monitor the patient's progress, because development of tolerance is usually paralleled by an increase in the MUD.

If the initial MUD is very low, it is difficult to immediately start the patient on oral methoxsalen photochemotherapy. Initial exposures using UV-A alone may be performed until the MUD is increased to a level at which oral methoxsalen photochemotherapy can be initiated.

Mechanisms of action

The mechanisms of action for phototherapy and photochemotherapy in solar urticaria are not entirely known. The resulting epidermal thickening and increase in skin pigmentation may be important factors but are probably not the main mechanisms behind tolerance induction.

Some authorities have postulated a UV-induced increase in the mast cell degranulation threshold as a possible mechanism.

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Prevention

Sun exposure must be avoided or minimized because it is the primary causative agent of solar urticaria. Educate patients about practical measures, such the following:

  • Wearing protective clothing

  • Judiciously applying sunscreens with adequate protection against the causative wavelengths

  • Using UV protective shields over glass windows

  • Altering lifestyle to minimize time spent outside during the day - Ie, changing job hours and shifting to indoor recreational activities

Some patients with UV-A or visible, induced solar urticaria may find it helpful to use self-tanning lotions containing dihydroxyacetone.

If medical therapy is unsuccessful, some patients benefit from complete avoidance or, possibly, a combination of avoidance and medical therapy.

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