When the Sun Can Be Your Enemy

Dear Pharmacist,
You recently wrote an article about how good the sun can be for you in creating vitamin D. The instructions with the medication I take for acne (doxycycline) state that I should stay away from the sun, so I do. What can happen if I don’t?
D.P., Gainesville, Florida

Answer: The sun does help you make more D, so long as your liver and kidneys are healthy enough to activate D to a useable form. Some medications warn against sun exposure because of a side effect known as “photosensitivity.” It isn’t a given because not everyone who uses a photosensitizing drug is affected. Offending drugs of this type cause some people to suffer a dreadful sunburn, brown splotchy patches or skin rash. Some drugs are more likely to cause reactions than others. Depending on the medication, this side effect may or may not be reversible.

Doxycycline is an antibiotic often prescribed for acne and has a strong reputation for causing skin damage in some people who are photosensitive. It is one of many drugs that increase a person’s photosensitivity, so you could burn after only a few minutes of exposure, where it might normally take two hours to get sunburned. Sunburn is just one type of reaction; it is possible to experience other short-term effects such as hives, eye burn, itches, blistering or scaling of the skin. Chronic effects with certain photosensitizing drugs include premature aging of the skin, skin cancer, strong allergic reactions and even cataracts.

For the record, the FDA reports that many household substances also cause photosensitive reactions. Such ingredients are commonly found in deodorants, antibacterial soaps, artificial sweeteners, mothballs, nylon and wool fibers and cadmium sulfide, a chemical injected into the skin during tattooing.

Interestingly, many blood pressure reducing medications, female hormones, birth control pills, anti-inflammatory arthritis medications and diabetic medications have the potential to cause photosensitive reactions.