Sun exposure can make some people literally break out in hives. Unfortunately, many people with sun-sensitive skin don’t even realize they’re at risk. Are you one of them?

Sun sensitivity is the increased sensitivity or abnormal response of the skin to sun or artificial ultraviolet (UV) light. Sunlight or tanning beds can trigger unusual skin reactions (such as burning more quickly than usual) in people taking common antibiotics, heart medicines, and other medications. Luckily, “It’s absolutely fine to take these medications, it is just that people taking these drugs may need to be extra diligent about sun protection,” according to Deborah S. Sarnoff, MD, Vice President of The Skin Cancer Foundation.

While drug-induced sun sensitivity (also known as photosensitivity) can manifest in a variety of ways, most reactions are considered phototoxic or, less commonly, photoallergic. Phototoxic reactions typically appear as exaggerated sunburns, and occur up to 24 hours after exposure to the photosensitizing medication and UV light. The reaction is limited to sun-exposed skin, which can be itchy and sore. In severe cases, blisters may form.

Photoallergic reactions, which can appear all over the body, do not develop until one to three days after the substance has come into contact with the body, when the immune system mounts a response to the allergen. Photoallergies, like other allergies, tend to occur in previously sensitized individuals and are generally caused by topical medications or cosmetic ingredients such as musk ambrette, sandalwood and bergamot oils. Repeat exposure to the same allergen plus UV light can prompt itching, red bumps, scaling, and oozing lesions similar to eczema.

While there are many medications, including over-the-counter pain relievers (such as ibuprofen), oral contraceptives, and antidepressants that may cause phototoxic or photoallergic reactions, the most common ones include antibiotics (tetracyclines, fluoroquinolones, and sulfonamides); diuretics (furosemide and hydrochlorothiazide); and oral and topical retinoids (isotretinoin, acitretin, tazarotene, and tretinoin).

“Photosensitivity will vary based on the individual,” Dr. Sarnoff explained. “Two people can take the same medication and one will have a reaction and the other won’t. The keys to preventing a phototoxic reaction are patient education and taking the proper precautions.” Photosensitive individuals should:

• Seek the shade: If outside for any length of time, find a pavilion roof or large, leafy tree to stay under. Or, carry shade with you — bring a sun umbrella.
• Wear protective clothing: All clothing provides some degree of sun protection; however, densely woven and bright- or dark-colored fabrics provide greater defense. Long sleeves and long pants cover more of the body, while a broad-brimmed hat helps protect the face, ears, and back of the neck. For all-day outdoor activities, consider specially formulated sun-protective clothing with a UPF (ultraviolet protection factor, a measure of the material’s sun-protective qualities) of 50.
• Use a broad-spectrum sunscreen with an SPF of at least 30: For photosensitive people, the higher the SPF (Sun Protection Factor, an indication of the product’s ability to screen UVB radiation), the better. Additionally, be sure the sunscreen contains some combination of UVA-blocking ingredients such as avobenzone, ecamsule (a.k.a. Mexoryl™), oxybenzone, zinc oxide, and titanium dioxide.
• Use the right amount of sunscreen: Most people do not apply enough sunscreen. People with heightened sun sensitivity should be especially careful to use at least one ounce (two tablespoons), including a nickel-sized dollop on the face.
• Apply sunscreen one-half hour before sun exposure: This gives it time to fully absorb and bind to your skin.
• Reapply sunscreen every two hours, since sunscreen gradually breaks down in the sun and wears off. Also reapply immediately after swimming or sweating heavily.

For more information on photosensitivity, please see Photosensitivity — A Reason to be Even Safer in the Sun