What is it?

Photosensitivity is an allergy to sunlight — especially excessive exposure — which can cause a multitude of rashes on the skin. The severity of these rashes varies from person to person. Such skin reactions are triggered by an immune system response that interprets “sun-altered” skin as a threat to the body, reports the Web site, YourTotalHealth.

According to The Merck Manual online medical dictionary, there are three main types of photosensitivity:

• Solar urticaria: Comes on quickly, sometimes after as little as 10 minutes in the sun. Symptoms do disappear within a few hours. Often, people with this condition continue to develop symptoms indefinitely for many years.

  • Symptoms: Hives covering the exposed areas and possibly accompanied by nausea, dizziness or headache.

• Chemical photosensitivity: A reaction that occurs as a result of oral or topical medications that causes UV sensitivity.

  • Symptoms: Inflammation and redness, or sometimes even brown or blue discoloration. The occurrence of itchiness and hives may indicate a drug allergy, brought on by exposure to sunlight.

• Polymorphous light eruption: Usually occurs among women or people who are seldom exposed to the sun, although the actual cause isn’t yet understood. For some individuals, increased exposure to the sun will reduce sensitivity over time.

  • Symptoms: Red patches and small red bumps appear anywhere from 30 minutes to several hours after sun exposure. Although new patches can continue to occur for several days, generally all symptoms clear up within a week.

Causes

Skin care professionals aren't sure why some people are more sensitive to sun exposure than others, but several pre-existing conditions may lead to photosensitivity:

• Lupus
• Herpes
• Skin disorders including rosacea, acne and psoriasis
• Genetic disorders

To know if a pre-existing condition is to blame for photosensitivity, consult a doctor.

Check your treatments

Many medications, essential oils and skin care products and treatments can cause the skin to become more sensitive to UV light.

• Medications: Often, an increased risk of sun sensitivity is indicated on the label of your medication. Browse your medicine cabinet for these common culprits:

  • Antibiotics
  • Accutane
  • Oral contraceptives
  • Diuretics
  • Antidepressants
  • Anti-fungals
  • Diabetes drugs
  • Anti-inflammatory drugs
  • Sulfa drugs

Additionally, St. John's wort, an herb commonly used to treat depression, can increase sensitivity to sunlight. When taking this herb, be on the lookout for any rashes or burns following sun exposure.

Diagnosis

If you notice symptoms that signal sun sensitivity, check the labels on your medications and consult your doctor. He or she will evaluate your skin and consider your exposure to potentially sun-sensitive substances when making a diagnosis.

A diagnosis may include one of the following procedures to determine the cause of photosensitivity:

• Blood tests: A small sample of blood is drawn and analyzed to find out whether other medical conditions are responsible.

• Skin biopsy: A very small section of skin is removed and examined under a microscope.

• Phototesting: Skin is exposed to small amounts of controlled UV light to determine which type of light (UVA or UVB) is causing the reaction, if any.

• Allergy tests: A small amount of a suspected allergen is injected into the skin and the doctor watches for potential reactions to pinpoint the perpetrator.

Prevention

Whether the cause of sensitivity is a genetic predisposition, a new medication or a skin care product, prevention is crucial. Here are some tips:

• Avoid the sun: During the summer, avoid going outdoors when the sun's rays are strongest — usually between the hours of 10 a.m. and 4 p.m. To protect skin when driving, consider having car windows tinted to block UV light.

• Wear protective clothing: When outside, wear clothing that doesn't allow sunlight to pass through the fabric, such as tightly woven materials and dark colors. Also, look for clothing that’s been treated with SPF protection.

• Slop on sunscreen: If you’re photosensitive, to simply stay out of direct sunlight isn’t enough. Sunscreen must be worn daily, even on days when you aren't planning on being outdoors for a long time; UV rays can pass through windows and clothing, and reactions can occur even while sitting in the shade.

  Also, keep in mind that not all sunscreens are created equal. Individuals who are photosensitive may experience an allergic reaction to some sunscreens. Find a formula that’s hypoallergenic and free from chemicals such as PABA (para-aminobenzoic acid), benzophenone or avobenzone (butyl methoxydibenzoylmethane), which can irritate the skin.

  Instead, use a broad-spectrum, physical sunscreen that contains zinc or titanium oxide. Opt for a waterproof formula with an SPF 30 or higher. Apply 15 to 30 minutes before going outdoors. Reapply it throughout the day if you’re outside for an extended period of time or when you’re engaging in activities like swimming or sports.

Product picks

• Pre-sun: Protect the skin year-round from UV rays with SkinCeuticals Physical UV Defense SPF 30, a transparent formula that contains zinc and titanium dioxide that’s safe for sensitive skin and children.

  To boost the efficacy of your sunscreen and prevent free radical damage, consider an oral supplement such as Murad Pomphenol Sunguard Dietary Supplement, which contains pomegranate extract and Ellagic acid. Be sure to consult your physician before taking any supplement.

• Post-sun: Once the skin has reacted to the sun, at-home treatments such as cooling baths or soothing lotions can be helpful. Korres Yogurt Cooling Gel can be applied as often as necessary to cool inflamed skin.

See also:

Intrinsic and Extrinsic Aging

10 Simple Secrets to Healthy Hair

Keep Your Skincare Simple

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Treating Sun Spots with Lightening Products