From the Guidelines
Cetirizine (Zyrtec) and fexofenadine (Allegra) are the recommended antihistamines for allergic rashes caused by the sun, with cetirizine often being the first choice. The standard adult dose is 10mg once daily for cetirizine or 180mg once daily for fexofenadine. These second-generation antihistamines are preferred because they effectively block histamine release that causes itching, redness, and swelling while causing less drowsiness than older antihistamines 1. For severe sun allergies, you may need to take the medication before sun exposure and continue daily during periods of high sun exposure. Some key points to consider when treating sun-induced allergic rashes include:
- Combining the antihistamine with sun protection measures is essential - wear broad-spectrum SPF 30+ sunscreen, protective clothing, and limit sun exposure between 10am-4pm.
- If your rash is severe, persistent, or accompanied by other symptoms like difficulty breathing, seek medical attention as you may need prescription-strength treatments such as corticosteroids.
- In some cases, treatment of solar urticaria with phototherapy can potentially result in provocation, syncope, and anaphylaxis, highlighting the importance of careful management and consideration of alternative treatments 1.
From the FDA Drug Label
The FDA drug label does not answer the question.
From the Research
Antihistamine Recommendations for Allergic Rashes Caused by the Sun
- There are no specific studies that directly recommend an antihistamine for allergic rashes caused by the sun.
- However, cetirizine has been found to be effective in treating various forms of urticaria and reducing pruritus in atopic eczema 2.
- It is also important to note that antihistamines can be used to treat contact dermatitis, which can be caused by exposure to allergens and irritants, including those found in sunscreen products 3.
- In the treatment of contact dermatitis, antihistamines can be used to reduce skin inflammation and relieve symptoms such as itching and burning 3.
- Some studies have also discussed the potential for antihistamines to cause contact dermatitis, highlighting the importance of patch testing and careful selection of medications 4, 5.