Photosensitivity Reaction to Medications

Photosensitivity is a skin reaction (i.e., rash) that occurs after exposure to ultraviolet (UV) radiation from the sun or an artificial light source. Photosensitivity can be caused by various agents, including drugs, perfume, cosmetics, and even the sunscreen that is meant to protect your skin. It is estimated that one in 100 people are affected by photosensitivity.

The condition can occur even after brief exposure to sunlight in both warm and cold weather. Photosensitizing agents can be topical medications or medications that are taken orally. Some people continue to be sensitive to sunlight long after discontinuation of the offending medication or lotion.

Phototoxic Reactions

There are two main types of sun-sensitizing drug reactions: phototoxic and photoallergic. Phototoxic reactions account for 95% of all cases of photosensitivity—occurring as a result of ingestion of certain drugs. The incidence and severity of phototoxic reactions have been directly linked to the drug's dosage and the amount of UV exposure.

In a phototoxic reaction, drug molecules absorb the energy of a specific UV wavelength, which causes the molecule to undergo a chemical change and emit energy that damages surrounding tissues. The reaction is often immediate. It usually occurs after the first dose of a drug and within 24 hours of taking the drug and exposure to the sun. Symptoms include severe redness on the areas of skin exposed to light, akin to an exaggerated sunburn with severe tenderness.

For drugs taken in high doses, blisters, edema (swelling), and urticaria (hives) may also be present. These symptoms usually resolve within 2 to 7 days of withdrawing from the drug therapy.

Drug categories which are associated with photosensitivity include but are not limited to:

• NSAIDs
• Diuretics
• Antibiotics
• Tricyclic antidepressants

Photoallergic Reactions

Photoallergic reactions are caused by the reaction of a topical ointment with UV radiation. Topical ointments are applied directly to the skin. Reactions may develop after one to 10 days of exposure but often recur within 24 to 48 hours of re-exposure. In a photoallergic reaction, the ointment, which can include cosmetic creams and sunscreen, absorbs the UV energy and binds to the protein in the skin, causing an allergic or eczema-type rash. A photoallergic reaction may also occur over skin areas not exposed to the sun and may develop with even a small amount of the irritating topical agent.

Preventative Measures and Recommendations

If you are taking any of the drugs thought to cause photosensitivity, your best bet is to avoid sun exposure. If you must venture outside, minimize your exposure in terms of duration, time of day, and clothing you choose to wear. Take extra precautions to shield yourself from the sun. Light-colored clothing, long-sleeve shirts, long pants or skirts, sunglasses, sunscreen that is rated SPF-30 or higher, and a wide-brimmed hat are important protection, but they will not totally block UV radiation.

Sunscreens containing physical blockers, such as zinc oxide and/or titanium dioxide, are recommended as a preventive measure against sun sensitivity.

Drugs Associated With Photosensitivity Reactions

Antibiotics

• Cipro (ciprofloxacin), Levofloxacin
• Minocin (minocycline)
• Tetracycline
• Sulfonamides
• Vibramycin (doxycycline)

Disease-Modifying Anti-Rheumatic Drugs

• Azulfidine (sulfasalazine)
• Gold
• Methotrexate
• Plaquenil (hydroxychloroquine)

NSAIDs

• Feldene (piroxicam)
• Ibuprofen (less likely)
• Naproxen and others

Antihypertensives

• Captopril
• Cardizem (diltiazem)
• Methyldopa
• Procardia (nifedipine)

Hypoglycemics

• glyburide
• Glucotrol XL (glipizide)

Antidepressants

• Amitriptyline
• Imipramine
• Norpramin (desipramine)
• Pamelor (nortriptyline)
• Silenor (doxepin)
• Trazodone

Antihistamines

• Benadryl and others

Diuretics

• Diuril (chlorothiazide)
• Hydrochlorothiazide
• Lasix (furosemide)

Retinoids

• Acitretin
• Amnesteem (isotretinoin)

Others

• Oral contraceptives
• Xanax (alprazolam)