by Chiara Daina
The most common form is polymorphic solar dermatitis: diagnosis is possible with a photosensitivity test. The interaction between sun rays and medicines or cosmetics can lead to photo allergies
There are no real allergies to the sun, but conditions of hypersensitivity and intolerance of the skin to the sun’s rays, which generally manifest themselves with itchy skin rashes. «Having a clear phototype is a risk factor but it can affect all skin types. The causes are still little known, there may be a genetic predisposition or the reaction can be triggered by the use of drugs, in particular antibiotics, or by cosmetic products containing chemicals» explains Giuseppe Argenziano, full professor of dermatology at the Vanvitelli University of Naples and president of the Italian Society of Dermatology and Sexually Transmitted Diseases.
In solar polymorphous dermatitis
The most common form of what are commonly called “sun allergies” is polymorphic solar dermatitis. It occurs in both sexes, but women are more prone to it. “The age range most affected is from 20-30 years to 50” specifies Argenziano. In fact, to prevent the inflammatory reaction and get the skin used to the sun’s rays, we recommend gradual exposure to the open air as early as spring and outpatient phototherapy sessions using special lamps that emit type A and B ultraviolet rays, different from tanning ones. ».
How it looks
What does polymorphic solar dermatitis look like? ‘With small reddish itchy bumps on parts of the body that are not exposed to the sun most of the year, particularly the shoulders, neck and chest. While in the most exposed locations the skin has developed a mechanism of tolerance to the sun – says the professor -. These signs appear a few hours or days after intense exposure to ultraviolet rays but leave no scars once treated and healed. Other possible symptoms in association with the papules: fever, headache, tiredness and low blood pressure.
The diagnosis
The reference specialist to contact is the dermatologist, “who will be able to diagnose this form of dermatitis through a photosensitivity test and in case of positivity prescribe a treatment with cortisone cream and antihistamines” informs Argenziano. In addition to pharmacological therapy, “it is essential to wear protective clothing, including a hat and sunglasses, use creams that completely shield from ultraviolet rays, even if the sky is cloudy, and take shelter from the sun during the hours when the rays are at their most strong, from 10 to 16 – underlines the doctor -. In about ten days the problem is solved. It is necessary to accustom the skin to sunlight gradually and repeatedly starting from the spring months to prevent the eruption of the papules or their aggressive return ».
The photo allergy
There are other forms of the so-called “solar allergies”, but much less frequent: solar urticaria, which appears after about 30 minutes of intense exposure, and actinic prurigo, characterized by papules, which can form plaques or nodules (thicker lesions). While photoallergic dermatitis, triggered by the interaction between sunlight and some chemical substances contained in drugs or cosmetics, or by vegetable substances, «are a form of true allergy – specifies the expert -. To identify the responsible substance, the patient must perform a photopatch test. It will be enough to eliminate its use to avoid the autoimmune reaction ». Finally, Argenziano adds: “Even sunburn is considered a mild form of ‘allergy’, which disappears as the skin tans”.
July 31, 2023 (change July 31, 2023 | 09:26)
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