What Is a Sun Allergy?
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Medically reviewed by Farah Khan, MD
A sun allergy—sometimes also called photosensitivity—occurs when your skin is hypersensitive to ultraviolet (UV) rays, a type of light that the sun naturally emits. When people with a sun allergy are exposed to sunlight or artificial UV rays, they may develop an itchy, painful, blistering, or peeling rash. This reaction can occur within minutes or hours of sun exposure and can vary in intensity from mild discomfort to severe skin irritation.
Genetics, certain medications, and underlying autoimmune conditions can cause sun allergies. Treatments for sun allergies range from lifestyle modifications to medications, depending on the severity and type of sun allergy. Researchers aren’t sure how many people sun allergies affect, but an estimated 2% to 18% of the worldwide population may live with a sun allergy.
Types of Sun Allergies
There are different types of sun allergies, each with its different causes, triggers, and symptoms. The four main types of sun allergy include:
Polymorphous light eruption (PMLE): PMLE is the most common type of sun allergy, mainly affecting people with fair skin. Within hours of sunlight exposure, an itchy or burning rash with red bumps or blisters develops, lasting from several days to two weeks. PMLE typically occurs in spring or early summer, as the skin is less acclimated to sunlight after winter.
Solar urticaria: A rare form of sun allergy that causes hives (raised, itchy welts) that appear on the skin within minutes of sun exposure and typically go away within 24 hours. Solar urticaria often occurs due to an abnormal immune response to UV rays.
Photoallergic reaction: This type of sun allergy occurs when ingredients in certain medications interact with UV rays, causing the immune system to overreact. As a result, you can develop a rash with red bumps or oozing blisters. The rash typically develops within one to three days after sun exposure.
Actinic prurigo: Actinic prurigo is a rare inherited sun allergy that causes itchy, bumpy, or scaly skin lesions after sun exposure. This condition is chronic and often begins in childhood before age 10.
Symptoms
Sun allergy symptoms can vary from person to person, depending on the severity and type of sun allergy they have. While some people may have only mild symptoms, others may develop more severe reactions to sunlight exposure.
Polymorphous Light Eruption (PMLE) Symptoms
PMLE symptoms usually develop within hours to four days after sun exposure. If you have PMLE symptoms, you may experience:
Redness or scaling of the skin
Small, red bumps or blisters on sun-exposed skin
Itchy or burning rash
Solar Urticaria Symptoms
Symptoms of solar urticaria often develop within minutes of sun exposure and may include:
Hives (raised, itchy welts) on sun-exposed skin
Redness and swelling in the exposed areas
Itching or burning sensation on the affected skin
Photoallergic Reaction Symptoms
Medications and certain cosmetic products may cause a photoallergic reaction to the sun. As a result, you might experience the following symptoms within hours or days of sunlight exposure:
Itchy rash or red blisters that develop on sun-exposed skin
Swelling and tenderness on the affected skin
A rash that spreads beyond sun-exposed areas
Actinic Prurigo Symptoms
With actinic prurigo, symptoms usually appear shortly after sun exposure and resolve within a few days. Additional sun exposure can re-trigger the allergic reaction to sunlight and cause a recurrence of symptoms, including:
Bumpy or scaly patches on sun-exposed skin
Burning or itching sensations
Red bumps, hives, or small blisters
Causes
Sun allergies occur when the skin has a hypersensitive reaction to sunlight or artificial ultraviolet (UV) rays (such as tanning beds). When you have a sun allergy and spend time in the sunlight, your immune system perceives UV rays as a threat, causing your immune system to produce and release inflammatory chemicals (e.g., histamines) to protect the body. The release of histamines and other immune system cells leads to skin inflammation, rash, and other sun allergy symptoms.
Specifically, the following causes and risk factors can increase your likelihood of developing sun allergy symptoms:
Polymorphous light eruption: Research suggests an abnormal immune reaction to UV light causes PMLE. A history of other skin conditions, a family history of PMLE, and people who live in northern climates and have fair skin are at an increased risk of developing PMLE.
Solar urticaria: What exactly triggers the immune response to sunlight or UV rays with solar urticaria is unknown. However, having fair skin, a family history of sun allergies, and a previous history of other allergic conditions can increase the risk of solar urticaria.
Photoallergic reaction: Certain medications and cosmetics are linked to allergic reactions after exposure to sunlight. Substances in certain medications (e.g., antibiotics, antihistamines, nonsteroidal anti-inflammatory drugs) and cosmetics (e.g., benzoyl peroxide or retinol) can sometimes trigger an immune response, which leads to skin inflammation and rash.
Actinic prurigo: An inherited (genetic) sun allergy that predominantly affects people with indigenous ancestry in Central and South America. A family history of actinic prurigo increases the risk of developing actinic prurigo.
Diagnosis
If you notice a rash, itchiness, or bumps on your skin after being in sunlight, it's a good idea to reach out to your healthcare provider for testing. To diagnose a sun allergy, your healthcare provider will thoroughly review your personal and family medical history, ask about your symptoms (such as when they developed and how long they lasted), and perform a physical examination.
Your healthcare provider will generally try to rule out other possible causes of your symptoms. They may evaluate your symptoms using one or more of the following tests:
Phototesting: Involves exposing small areas of the skin to controlled amounts of UV light to observe any allergic reactions. This test helps determine the specific wavelength of light (UVA or UVB) that triggers an allergic reaction.
Patch testing: Helps identify photoallergic reactions. A provider will apply small amounts of potential allergens (e.g., medications or certain substances found in cosmetics) to patches and place the patches on the skin. Then, your provider will expose the patches to UV rays and ask you to return to the office later so they can examine your skin to look for allergic responses to the substances they placed on the patches.
Blood tests: Uses a sample of your blood, which your healthcare provider will send to a lab to rule out other conditions that can cause sun sensitivity, such as lupus.
Skin biopsy: Takes a small sample of your skin, which your provider sends to a lab technician to examine under a microscope. This helps them rule out other skin conditions, such as cancer, that may produce similar symptoms to a sun allergy.
Treatments
While there is no cure for most sun allergies, treatments can help relieve symptoms, reduce the frequency of allergic reactions, and improve your quality of life. Treatment options vary based on the specific type of sun allergy and the severity of symptoms. Your provider can recommend a combination of lifestyle changes, medications, and therapies.
Lifestyle Changes
Making adjustments to your lifestyle may help manage a sun allergy. This may include:
Avoiding direct sunlight during peak hours of the day (usually between 10 AM to 4 PM)
Wearing protective clothing, such as wide-brimmed hats, long sleeves, and UV-blocking sunglasses
Applying a broad-spectrum sunscreen with a high sun protection factor (SPF) to exposed skin
Identifying and avoiding specific substances (medications or cosmetics) that trigger the allergic response in combination with sunlight
Topical Medications
For mild sun allergies, your provider may recommend over-the-counter hydrocortisone creams or ointments that you can apply directly to the skin. These topical medications can help relieve itching and inflammation after an allergic reaction. In some cases, your provider may opt to prescribe stronger corticosteroid creams for more severe reactions.
Oral Medications
Your healthcare provider may prescribe oral medications (taken by mouth) for severe sun allergies to help you manage symptoms and prevent future allergic reactions. These medications may include:
Antihistamines to reduce itching and allergic reactions
Nonsteroidal anti-inflammatory drugs (NSAIDs) to help relieve pain and inflammation
Monoclonal antibodies, which block the body’s response to sunlight to reduce allergic reactions
Phototherapy (Light Therapy)
Light therapy uses a technique to give you controlled, gradual exposure to UV light that may help desensitize your skin to sun exposure and reduce reactions to sunlight. Phototherapy is a common treatment approach for PMLE.
How to Prevent a Sun Allergy
While there is no surefire way to prevent most sun allergies, there are several things you can do to help reduce the frequency and severity of allergic reactions to sunlight, such as:
Staying inside on hot days
Seeking shade during peak sunlight hours
Wearing protective clothing, sunglasses, and hats when outdoors
Applying a broad-spectrum sunscreen with a high SPF before sun exposure
Reapplying sunscreen throughout the day, especially if you are swimming or exercising outside
Being cautious about the medications or cosmetics you're using, as some can increase your sensitivity to the sun
Related Conditions
Certain conditions may increase your risk of developing a sun allergy. These include:
Atopic dermatitis (eczema): A chronic skin condition that causes itchy and inflamed skin. While sun exposure may help clear eczema in some people, research shows that some may experience worsened symptoms after sunlight exposure.
Systemic lupus erythematosus (SLE or lupus): An autoimmune disease that affects various body systems, including the skin. Some people with lupus may experience photosensitivity, where exposure to sunlight can trigger skin rashes and worsen the disease.
Psoriasis: A chronic skin condition that produces a rapid buildup of skin cells, leading to red, scaly patches that can be itchy and painful. While psoriasis is not directly related to sun allergies, some people with psoriasis may experience worsened symptoms when they have sun exposure.
Living With a Sun Allergy
Living with a sun allergy can profoundly affect your life, from everything between work to leisure activities with friends and family. While it can be challenging to live with a sun allergy, embracing lifestyle adjustments and taking your medications (if any) as prescribed can help you manage your symptoms, spend time outdoors, and lead a fulfilling life.
Frequently Asked Questions
Can you suddenly develop a sun allergy?
Yes, it is possible to suddenly develop a sun allergy, especially after exposure to certain medications, cosmetics, or environmental factors that make your skin more sensitive to sunlight.
Is sun allergy an autoimmune disease?
Sun allergies, including conditions like solar urticaria and actinic prurigo, are not classified as typical autoimmune diseases. While these reactions often involve abnormal immune responses, sun allergies are known as allergic reactions rather than autoimmune disorders.
What vitamin deficiency causes sun allergy?
Research shows that a severe niacin deficiency (a form of vitamin B3) is linked to sun allergy. Following a healthy, balanced diet may help reduce the risk of skin reactions to sunlight.
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