Vernon E. Ansdell

Description

• Travelers to the tropics and subtropics are at increased risk of overexposure to the sun. Important consequences include sunburn, premature aging of the skin, wrinkling, and skin cancer, including melanoma.
• Sunlight consists of ultraviolet (UV) rays (i.e., UVA, UVB, and UVC).
  • UVA rays are present throughout the day and are the most important cause of premature aging of the skin. In addition, UVA rays are responsible for photosensitivity reactions and also contribute to skin cancer.
  • UVB rays are intense from 10 am to 4 pm and are most responsible for sunburn and skin cancer development.
  • UVC rays are filtered by the ozone layer and do not reach the earth’s surface.
• The benefits of UV radiation include vitamin D protection, which is important for calcium absorption.

Occurrence and Risk for Travelers

Increased exposure to UV radiation occurs nearer the equator, during summer months, at higher elevation and between 10 am and 4 pm. Reflection from the snow, sand, and water increases exposure, a particularly important consideration for beach activities, skiing, swimming, and sailing.

Commonly Used Medications that May Cause Photosensitivity Reactions

Antimicrobials

Fluoroquinolones, sulfonamides, and tetracyclines (especially demeclocycline); less frequently, doxycycline, oxytetracycline, and tetracycline; rarely, minocycline.

Antimalarials

Doxycycline.

Others

Nonsteroidal anti-inflammatory drugs, thiazide diuretics, furosemide, amiodarone, sulfonylureas, acetazolamide (Diamox), phenothiazines.

Clinical Presentation

• Symptoms from sunburn appear 3–5 hours after overexposure, worsen over the next 24–36 hours, and resolve in 3–5 days.
• Serious burns are painful, and the skin may be tender, swollen and blistered. There may be fever, headache, itching, and malaise. Skin peeling occurs 3–8 days after excessive sun exposure.
• Overexposure to the sun over several years leads to premature aging of the skin, wrinkling, age spots, and an increased risk for skin cancer, including melanoma.
• Overexposure to the sun can cause red, dry painful eyes. Repeated exposure to sunlight results in pterygium formation and important causes of blindness such as cataracts and macular degeneration.

Preventive Measures for Travelers

Sun Protection Factor (SPF)

SPF defines the extra protection against UVB rays that an individual will get by using a sunscreen. For example, if a person using SPF 15 sunscreen normally acquires a sunburn within 20 minutes without protection, the benefit will be 20 × 15 minutes extra protection with sunscreen (i.e., 300 minutes = 5 hours). SPF does not refer to protection against UVA rays. Products containing Mexoryl, Parsol 1789, titanium dioxide, zinc oxide, or avobenzone block UVA rays.

UV Index

The UV index provides travelers with an indication of the risk of UV radiation. Information is often available on the Internet or in local newspapers. The UV index ranges from 1 (low) to 11 or higher (extremely high).

Sun Avoidance

Staying indoors or seeking shade between 10 am and 4 pm is very important in limiting exposure to UV rays, particularly UVB rays. Be aware that sunburn and sun damage can occur even on cloudy days.

Protective Clothing

• Wide-brimmed hats and long sleeves and pants provide important protection against UV rays.
• Tightly woven clothing and darker fabrics provide additional protection.
• High SPF sun-protective clothing is recommended for those at increased risk of sunburn or with a history of skin cancer. This type of clothing contains colorless compounds, fluorescent brighteners, or specifically treated resins that absorb UV rays and often provides an SPF of 30 or higher.
• Sunglasses that provide 100% protection against UV radiation are strongly recommended.

Sunscreens

Sunscreens protect the skin by absorbing or reflecting UV radiation.

Physical Sunscreens contain large particulate substances such as titanium dioxide and zinc oxide, which act to reflect and scatter both visible and UV light. They are effective sunscreens but are less popular because of aesthetically unappealing characteristics such as opaqueness and tendency to stain clothing. They are recommended for those who burn easily or who take medications that may cause photosensitivity reactions.

Chemical Sunscreens absorb rather than reflect UV radiation. A combination of agents is recommended to provide broad-spectrum protection against UVA and UVB rays.

Key Points Regarding Sunscreens

• Choose a sunscreen with at least 15 SPF.
• Select a water- and sweat-resistant product that provides protection against both UVA and UVB rays.
• Look for a sunscreen with at least three different active ingredients to provide broad-spectrum UVA and UVB ray protection. These ingredients generally include PABA derivatives, salicylates (homosalate, octyl salicylate), or cinnamates (octyll methoxycinnamate and cinoxate) for UVB ray absorption; benzophenones (oxybenzone, dioxybenzone, sulisobenzone) for shorter-wavelength UVA ray protection; and avobenzone (Parsol1789), ecamsule (Mexoryl), titanium dioxide, or zinc oxide for the remaining UVA spectrum.
• Apply 30 minutes before exposure to the sun.
• At least 1 oz of sunscreen is needed for total body application (i.e., quarter of a 4-oz bottle).
• Apply to all exposed areas, especially the ears, scalp, lips, back of the neck, tops of the feet, and backs of the hands.
• Reapply after 1–2 hours and after sweating, swimming, or toweling (even on cloudy days).
• Many sunscreens lose potency after 1–2 years.
• Sunscreens should be applied to the skin before insect repellents.
• Avoid products that contain sunscreens and insect repellents. (DEET-containing insect repellents may decrease the effectiveness of sunscreens and may increase absorption of DEET through the skin.

Treatment

• Hydration and staying in a cool, shaded, or indoor environment
• Topical and oral nonsteroidal anti-inflammatory drugs decrease erythema if used before or soon after exposure to UVB rays and may relieve symptoms such as headache, fever, and local pain. Topical steroids are of limited benefit, and systemic steroids appear to be ineffective.
• Moisturizing creams, aloe vera, and diphenhydramine may help to relieve symptoms.
• In severe cases, narcotic analgesics may be indicated to relieve pain.

References

1. Kaplan LA, Exposure to radiation from the sun. In: Auerbach PS, editor. Wilderness medicine. 5th ed. Philadelphia: Mosby; 2007. p. 351–71.
2. McClean DI, Gallagher R. Sunscreens. Use and misuse. Dermatol Clin. 1998;16(2):219–26.
3. Diffey BL, Grice J. The influence of sunscreen type on photoprotection. Br J Dermatol. 1997;137(1):103–5.
4. Murphy ME, Montemarano AD, Debboun M, et al. The effect of sunscreen on the efficacy of insect repellent: a chemical trial. J Am Acad Dermatol. 2000;43:219–22.
5. Gu X, Wang T, Collins DM, et al. In vitro evaluation of concurrent use of commercially available insect repellent and sunscreen preparations. Br J Dermatol. 2005;152(6):1263–7.
6. Han A, Maibach HI. Management of acute sunburn. Am J Clin Dermatol. 2004;5(1):39–47.