Summary about Disease
Solar urticaria is a rare, chronic inducible urticaria (hives) triggered by exposure to ultraviolet (UV) and/or visible light. The reaction typically appears within minutes of exposure and resolves within a few hours after cessation of exposure. It significantly impacts quality of life due to the need for strict sun avoidance.
Symptoms
Itchy skin
Redness of the skin (erythema)
Hives (wheals), which are raised, red bumps or welts
Burning or stinging sensation
Swelling (angioedema), particularly of the face, lips, or eyelids (less common)
Headache, nausea, and wheezing (rare, in severe cases)
Causes
The exact cause is unknown, but it is believed to be an immunological reaction. When exposed to UV or visible light, the body produces an unknown antigen (a substance that triggers an immune response). This antigen then causes mast cells in the skin to release histamine and other chemicals, leading to the typical symptoms of urticaria. Some research suggests a possible role of porphyrins or other light-absorbing molecules within the skin.
Medicine Used
Antihistamines: H1 antihistamines are the first-line treatment to reduce itching and hives. Both first-generation (e.g., diphenhydramine) and second-generation (e.g., cetirizine, loratadine, fexofenadine) antihistamines can be used, although second-generation antihistamines are preferred due to fewer sedative side effects.
H2 Antihistamines: Sometimes used in combination with H1 antihistamines to further reduce histamine release.
Corticosteroids: Topical corticosteroids can help reduce inflammation. Systemic corticosteroids (oral or injectable) are reserved for severe cases due to potential side effects.
Omalizumab: A monoclonal antibody that targets IgE. It is sometimes used in cases refractory to other treatments.
Phototherapy/Photochemotherapy (PUVA): Gradual exposure to controlled doses of UV light to desensitize the skin. Narrowband UVB is also sometimes used.
Immunosuppressants: In severe, refractory cases, medications like cyclosporine or azathioprine may be considered.
Is Communicable
No, solar urticaria is not communicable. It is not contagious and cannot be spread from person to person.
Precautions
Sun Avoidance: The most important precaution is to minimize exposure to sunlight and artificial UV light.
Protective Clothing: Wear tightly woven, long-sleeved shirts, long pants, wide-brimmed hats, and sunglasses.
Sunscreen: Use broad-spectrum sunscreens with high SPF (30 or higher) that protect against both UVA and UVB rays. Apply generously and reapply frequently, especially after swimming or sweating.
Window Tinting: Tint windows in cars and homes with UV-blocking film.
Avoid Peak Sun Hours: Stay indoors during the peak sun hours, typically between 10 AM and 4 PM.
Know Your Triggers: Determine the specific wavelengths of light that trigger your symptoms (through phototesting) to better avoid them.
How long does an outbreak last?
Individual outbreaks typically last from 30 minutes to a few hours after sun exposure is stopped. However, the condition itself is chronic, meaning it can persist for many years or even a lifetime.
How is it diagnosed?
Medical History and Physical Exam: The doctor will ask about your symptoms, when they occur, and any potential triggers. A physical examination will be performed to assess the skin.
Phototesting: This is the most important diagnostic test. It involves exposing small areas of skin to different wavelengths and intensities of UV and visible light to see which wavelengths trigger a reaction.
Skin Biopsy: Rarely needed, but may be performed to rule out other skin conditions.
Blood Tests: May be done to rule out other underlying medical conditions.
Timeline of Symptoms
Within Minutes of Exposure: Itching, tingling, or burning sensation begins.
5-10 Minutes: Redness (erythema) appears.
10-30 Minutes: Hives (wheals) develop.
30 Minutes to Several Hours After Exposure Stops: Symptoms typically resolve, though redness may linger.
Important Considerations
Impact on Quality of Life: Solar urticaria can significantly impact daily life due to the need for strict sun avoidance. This can affect work, social activities, and mental health.
Psychological Support: Consider seeking support from a therapist or support group to cope with the challenges of living with solar urticaria.
Vitamin D Deficiency: Due to sun avoidance, individuals with solar urticaria are at risk for vitamin D deficiency. Supplementation may be necessary; consult with a healthcare provider.
Accurate Diagnosis is Key: Other conditions, such as polymorphous light eruption (PMLE), can mimic solar urticaria. Accurate diagnosis is crucial for appropriate management.
Individualized Treatment: Treatment plans need to be individualized based on the severity of symptoms, triggering wavelengths, and overall health. Regular follow-up with a dermatologist or allergist is important.