If, after spending a couple of hours in the sun, you develop a rash or hives on the "V" of your neck, chest, and arms, you more likely experience photosensitivity or photodermatoses – sun-related skin conditions that are often mistaken for allergies. True sun allergy (solar urticaria) is fairly rare, but photosensitivity is not.
Photosensitivity disorders of the skin are conditions in which an abnormal cutaneous response occurs after exposure to ultraviolet radiation (UVR) or visible light. It can be triggered by various agents such as drugs, perfume, cosmetics, and even the sunscreen.
When experiencing photosensitivity, one of two separate reactions could occur – phototoxic (account for more than 90% of all cases) or photoallergic reactions.
PHOTOTOXIC REACTIONS. Phototoxic reactions resemble an exaggerated sunburn and result from direct tissue or cellular damage following exposure to a phototoxic agent and UVR. Most drug-induced photosensitivity reactions are phototoxic.
PHOTOALLERGIC REACTIONS. A photoallergic reaction is a form of allergic contact dermatitis in which a photosensitizing chemical or drug once activated by UVR serves as the allergen and elicits an eczematous reaction in a sensitized individual. Most photoallergic reactions are caused by topical agents, rather than systemic medications.
IDIOPATHIC PHOTODERMATOSES. The idiopathic photodermatoses are photosensitive disorders, many of which may be immunologically mediated, although the inciting agents are unknown.
One of the most common form - roughly affecting 10% to 15% of the U.S. population – is polymorphous light eruption (PLE). Shortly after sun exposure a person's skin around the chest, upper arms, backs of the hands becomes red, raised and itchy. It can take up to a week for the symptoms to go away.
In many cases, time alone will resolve the problem. PLE tends to flare up in spring and early summer after several hours of being exposed in the sun. As the summer progresses, symptoms ease up or disappear altogether. However, PLE can recur every year after the first episode.
A severe form of idiopathic photodermatoses is solar urticaria, also known as sun allergy. Large hives could occur on exposed skin after just a few minutes in the sun. A reaction could start with itching and burning and then develop into welts, affecting large areas of the skin.
Once you are out of the sun, symptoms disappear. It rarely lasts longer than 24 hours and tends to go away on its own. Solar urticaria is a rare condition but can be life-threatening. If you suspect you’ve experienced solar urticaria, it’s best to talk to a specialist.
The cause of photodermatoses (photosensitivity) is still unknown, but some drugs can potentially trigger it:
Antibiotics (ciprofloxacin, doxycycline, levofloxacin)
Antihistamines (cetirizine, diphenhydramine, loratadine)
Acne (doxycycline) and anti-aging creams
NSAIDs pain relievers (Ibuprofen, naproxen, ketoprofen)
Cardiac drugs
Blood pressure drugs
Birth control pills
If you think you experience photosensitivity that is severe or persistent, see a specialist to discuss a medical treatment.
And remember, prevention is just as important as treatment. In many cases, avoidance of the sun and adherence to a strict sunscreen routine are the best means of protection.
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