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The Family Practice Newsletter
The Ohio University College of Osteopathic Medicine
The Ohio Northern University Raabe College of Pharmacy
Doctors Hospital Family Practice
Volume 5, Issue 12
July 2006
Appropriate sunscreen use with a focus on photosensitizing medications
Erin Hudeck, ONU Doctor of Pharmacy Candidate
Exposure to ultraviolet radiation can lead to serious problems, including premature skin aging,
precancerous and cancerous skin lesions, and sunburn. Of these, sunburn is the most common, yet it is very
preventable with the proper use of sunscreen. Unfortunately, the average consumer does not know the difference
between ultraviolet A (UVA) and ultraviolet B (UVB) radiation, the meaning of SPF, or the proper use of
sunscreen products. Patient education on these three key points can help prevent sunburn, skin aging, and cancer.
UVA radiation penetrates deeper into the skin and primarily affects the dermis. Although not usually
responsible for sunburn, UVA rays are responsible for sagging skin, thickening of the dermis and epidermis, and
increasing elastase activity. UVA is involved in the tanning process in two ways: immediate pigment darkening
lasting for up to 24 hours, and delayed tanning which contributes to the development of a slow natural tan. UVB
radiation is primarily responsible for causing sunburn, wrinkling of the skin, epidermal hyperplasia, elastosis,
and collagen damage. UVB is also involved in the tanning process. It stimulates epidermal hyperplasia and shifts
melanin up through the skin. Skin cancer is primarily caused by UVB radiation, but UVA rays augment this
effect. It is therefore important to protect the skin against both UVA and UVB radiation to prevent sunburn, skin
aging, and cancer.
It is not only important to protect the skin on sunny, hot, summer days, as it is possible to be exposed to
UVR all through the year and in cloudy places. Seventy to ninety percent of ultraviolet radiation (UVR)
penetrates clouds. Fresh snow reflects 85 to 100 percent of radiation, and sand and white painted surfaces reflect
a significant amount of radiation. This means that it is possible to sunburn on a cloudy day, in the winter, or even
when sitting under an umbrella at the beach. Conversely water reflects no more than 5 percent of UVR, meaning
that the remaining 95 percent penetrates through, making sunburn possible while swimming under the water.
Also of note, UVB radiation does not penetrate window glass, but UVA does. Therefore, patients sensitive to
UVA radiation may be exposed while driving a car, even with the windows rolled up.
Especially at risk for sun burn are patients with photodermatoses and medication induced
photosensitivity. Drug photosensitivity encompasses two conditions: photoallergy and phototoxicity.
Photoallergy is relatively uncommon, involves an immunologic response, and presents similar to allergic contact
dermatitis. Phototoxicity is increased reactivity of the skin to UVR and presents as exaggerated sunburn with
itching. See table 1 for a partial list of medications known to induce photosensitivity reactions.
In order to prevent short and long term sun damage, it is imperative that patients choose the correct sun
protection. Many factors should be considered when choosing sun protection such as: skin type and color,
activity being performed, length of exposure, and presence of photosensitizing factors. Persons at risk for the
development of UVR-induced problems include: those with fair skin that always burn; a history of one or more
serious, blistering sunburns; blonde or red hair; blue, green or grey eyes; freckles; family history of melanoma;
excessive lifetime exposure to UVR, current use of immunosuppressive agents, current use of photosensitizing
agents, or a UV-induced disorder. Patients with multiple risk factors should use higher SPF protection.
Specifically, patients with current use of photosensitizing agents or a UV-induced disorder should use a broad
spectrum sunscreen containing avobenzone with an SPF of at least 30.
When applying sunscreen, it is necessary to reapply at intervals of 40 to 80 minutes depending on the
labeling of each particular sunscreen. Generally water resistant sunscreen should be reapplied every 40 minutes
and waterproof or very water resistant sunscreen should be reapplied every 80 minutes as this is the amount of
time the sunscreen is expected to stay on the skin per the manufacturer.
There are two general classes of sunscreen: physical and chemical. Physical sunscreens are usually
opaque and reflect UVR. Common physical sunscreens include titanium dioxide and zinc oxide. Chemical
sunscreens work by absorbing and thus blocking transmission of UVR to the epidermis. Some chemical
sunscreens include aminobenzoic acid, avobenzone, and octocrylene
Once the correct sunscreen has been chosen, each patient must understand how to correctly use the
product in order for it to be effective. Patients should be told that suns rays are most powerful between 10am and
3pm. Approximately one ounce of sunscreen must be applied 15 to 30 minutes before exposure to the sun taking
care to avoid contact with the eyes. Sunscreen must be reapplied every 40 to 80 minutes in order to confer
continuing protection estimated by the SPF; reapplication does not increase the amount of time the patient can
stay out in the sun. Sunscreen bottles should be kept out of direct light as this may decrease potency. Sunscreens
may cause an allergic reaction, it is important to stop using the sunscreen if redness, itching, rash or exaggerated
sunburn occurs. Sunscreens are safe and effective for children 6 months and older. The risks and benefits of
sunscreen in infants younger than 6 months have not been identified. Infants should be kept out of direct sunlight
and covered with protective clothing including a hat. With correct patient education, many sunburns, premature
skin aging, and cancer can be prevented.
If a patient does not adequately protect their skin against UVR, the focus shifts to treatment of sunburn.
Most sunburns are minor, superficial burns that can be treated with over the counter remedies. Many options are
available for relieving the pain and discomfort of sunburn. Skin protectants including allantoin, cocoa butter,
petrolatum, shark liver oil, and white petrolatum are FDA approved to protect the burn from friction and also to
hydrate the burned skin. Skin protectants may be applied as often as the patient feels necessary. To relieve the
pain, an NSAID such as ibuprofen or naproxen should be used within the first 24 hours to decrease inflammation
mediated by prostaglandins. Topical anesthetics provide short-lived relief of pain lasting 15-45 minutes, and may
only be applied up to three or four times daily which only provides minimal relief. Examples of commonly used
topical anesthetics are benzocaine and lidocaine. Due to the risk of systemic absorption and toxicity, topical
anesthetics should not be used on broken skin. Topical hydrocortisone 1% may be used to combat inflammation,
although it is not FDA approved for sunburn relief. Hydrocortisone should not be used on broken skin because it
may promote bacterial growth. Topical antibiotics are of little value because most sunburns are superficial and
the skin is often intact. Aloe gel is often used to combat pain, itching, and dryness, but there is insufficient
evidence to support these claims. Although simple, cool water baths may provide relief to the patient. Any of the
above treatments may provide the patient with relief of pain or provide protection of the damaged skin.
Treatment is only symptomatic and will not reverse the damage caused by the sunburn, so it is important to
protect the skin against burn with sunscreen to prevent damage from occurring.
Table 1: Commonly used photosensitizing medications
TCA Antidepressants: amitriptyline, nortriptyline, imipramine; trazodone
Antihistamines: brompheniramine, chlorpheniramine, clemastine,cyproheptadine, dimenhydrinate,
diphenhydramine, hydroxyzine, meclizine, promethazine
Antihypertensives: ACEI’s, Calcium channel blockers, methyldopa
Diuretics: Thiazide agents, Loop’s, triamterene
Hormones: Estrogen products, MPA, Progestin products
NSAIDS: diclofenac, ibuprofen, indomethacin, ketoprofen, naproxen
Antibiotics: sulfonamides, tetracyclines, fluoroquinolones
Others: phenytoin, carbamazepine, amiodarone, osotretinoin, lamotrigine, lovastatin
References:
1. DeSimone EM. Prevention of sun-induced skin disorders. In: Beradi RR, McDermott J, Newton GD, et al. Handbook of
nonprescription drugs: an interactive approach to self care. 14th edition. Washington DC: American Pharmaceutical Association; 2004.
2. Meurer LN, Jamieson B. What is the appropriate use of sunscreen for infants and children? J Fam Pract 2006; 55(5): 437-440.
3. Lenane P, Murphy GM. Sunscreens and the photodermatoses. J Dermatolog Treat 2001; 12: 53-57.
4. Bowman JD, Moore RH. Minor burns and sunburn. In: Beradi RR, McDermott J, Newton GD, et al. Handbook of nonprescription
drugs: an interactive approach to self care. 14th edition. Washington DC: American Pharmaceutical Association; 2004.
The Family Practice Newsletter is edited by Stephanie Gibson, Pharm.D., Director of Clinical Pharmacy Services at Doctors Hospital Family
Practice and Assistant Clinical Professor, ONU Raabe College of Pharmacy. Address questions and/or comments to [email protected].