By Margaret Songy, Pharmacy Resident, BHMC-North Little Rock
Have you ever wondered if your sunburn could have been related to the medication you were taking? Ever experienced burning and itching after applying certain brands of sunscreen?
These situations can be labeled as either phototoxicity or photoallergy, and with the summer season approaching it is important that you understand the potential reactions that some of your medications can have with the sun.
Phototoxicity (photoirritation) is defined as a toxic response that happens when your skin is first exposed to sunlight after administration of a particular chemical, specifically medication.
Phototoxicity can result when a person uses one or another of a wide range of photosensitizing products (products that enhance the reactivity of your skin to sunlight) and then is exposed to ultraviolet radiation, most commonly from sun exposure.
Typically, the initial reaction resembles severe sunburn and will appear within minutes to hours of sun exposure. Many of the photosensitizing products are medications such as those in the following table:
|Antibiotics||Tetracyclines(minocycline, doxycycline, tetracycline)
Fluoroquinolones(ciprofloxacin, ofloxacin, norfloxacin)
|NSAIDs(non-steroidal anti-inflammatory drugs)||Ibuprofen (Advil)
|Diuretics (water pills)||Furosemide (Lasix)
|Retinoids (acne medications)||Isotretinoin (Accutane)
Photoallergy is defined as a sensitivity to light that causes allergic reactions. Possible causes of photoallergic reactions could be fragrances, antiseptics found in antibacterial soaps, sunscreen, or even the medications listed in the table above.
Another class of medication that could potentially cause a photoallergic reaction is the sulfonylureas. This class of medication is used to treat diabetes and includes the medications glipizide (Glucotrol), glimepiride (Amaryl), and glyburide (Micronase).
Medication-induced photoallergy presents similar to allergic contact dermatitis (like poison ivy). Phototoxic reactions occur because of the damaging effects of light on cells and, in some instances, DNA. In contrast, photoallergic reactions are driven by your body’s immune response.
Of the two reactions, photoallergy is the least-common reaction, and photoallergic reactions develop in only a small number of people. The amount of medication required to elicit a photoallergic reaction is considerably smaller than the amount required for phototoxic reactions.
Moreover, photoallergic reactions often have a much later onset. You might not notice any reaction for as long as 24 to 72 hours after exposure to the medication and light.
Photoallergy, like other allergies, will not necessarily occur on the first exposure to light while taking a photosensitive medication. Random exposure to the ultraviolet rays from the sun while on the medication can launch a typical allergic reaction of intense itching and redness.
For some people, certain sunscreen ingredients cause photoallergy reactions. When this happens, you should switch sunscreens. Anyone with a known history of photosensitivity should stay out of the sun as much as possible and use generous amounts of sunscreen and other sun-protective measures.
If you think that you are reacting to your sunscreen, don’t hesitate to ask your pharmacist to suggest a suitable alternative.