Understanding Photodermatitis: Causes, Symptoms, and Prevention Methods
Photodermatitis is more likely to occur during the spring and summer when people switch from wearing heavy winter clothing to cooler, short-sleeved garments. This exposes skin, which has not been exposed to sunlight for a long time, to large amounts of ultraviolet radiation, thus making the skin prone to allergic reactions.
Patients with photodermatitis are allergic to the ultraviolet rays of the sun and can experience either acute or chronic reactions.
Acute Reactions
Upon exposure, the skin can develop eczema-like dotted red rashes, small papules, and blisters.
Chronic Reactions
Mostly, gray-white, scaly, circular patches that resemble bran appear on sun-exposed areas, and some cases can develop into small nodules the size of peas.
Sunburn vs. Photodermatitis
Both sunburn and photodermatitis are skin conditions caused by sun exposure. The primary difference is that sunburn results from excessive sun exposure, whereas photodermatitis is due to an individual’s sensitivity to sunlight. Sunburn essentially manifests as erythema caused by ultraviolet rays, with symptoms typically appearing 6 hours after exposure. Mild cases involve slight swelling and redness, while severe cases can exhibit significant swelling and blistering, accompanied by unbearable burning and pain. The most severe cases can lead to fever, electrolyte imbalance, and leukocytosis. If blisters break, bacterial infection may occur. Redness and swelling generally subside after 3-5 days, followed by peeling, sometimes leaving pigmentation without scarring if no complications arise.
How to Know If You Have Photodermatitis?
The intensity of the sunlight can be a clue. If within 5 minutes of sun exposure, the uncovered skin develops itchiness, papules, and red patches, and severe cases may lead to peeling and blistering, particularly on the outer sides of the arms, chest, back of the neck, and facial areas such as the cheeks, nose, and chin, it is likely photodermatitis.
Itching is the first sign, and symptoms usually subside if no further sun exposure occurs. However, if the itchiness becomes uncontrollable, it is best to seek medical treatment immediately. Otherwise, scratching the blisters open could lead to bacterial infection and chronic eczema.
How is Photodermatitis Treated?
Since photodermatitis is caused by an individual’s physical reaction to sunlight, it can only be managed, not cured. To prevent photodermatitis, patients should minimize their sun exposure. For outbreaks, treatment can involve oral antihistamines or a combination of topical steroids, prickly heat creams, and ultraviolet therapy.
Practical Prevention Methods for Photodermatitis
If sun exposure is necessary, it is best not to exceed 15 minutes, especially avoiding the sun from 9 a.m. to 3 p.m. when UV rays are strongest. Prepare for sun protection by using umbrellas, wearing hats, long-sleeved clothes, and applying sunscreen. Remember to stay hydrated to prevent skin dehydration when walking under the sun. Those with photosensitive constitutions should avoid eating photosensitive vegetables and fruits, as they can trigger the onset of photodermatitis.
Photosensitive Vegetables and Fruits
When sunlight irradiates vegetables and fruits containing coumarins and psoralens, these substances transform into photoreactive compounds. Once ingested and metabolized, these can form phototoxic substances in the body. Exposure to sunlight and individual constitution can then trigger photodermatitis. Examples of such produce include leaves of radishes, tomatoes, amaranth, eggplants, potatoes, cucumbers, lettuce, rape, mustard, spinach, coriander, celery, mushrooms, wood ear mushrooms, lemons, and citrus fruits.
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