Sunlight Exposure and Atopic Dermatitis

Sunlight may help improve atopic dermatitis (AD), the most common form of eczema. Many people with AD find their skin improves or clears in summertime, when there is more sunlight and more time is spent outdoors. In contrast, AD tends to worsen in winter, when the colder temperatures and lack of humidity frequently cause flare-ups of AD.1,2

The positive benefit of sunlight on skin affected by AD is behind the idea of phototherapy, the use of artificial light waves as a treatment. Phototherapy works by decreasing the inflammation in skin affected by AD. The American Academy of Dermatology recommends that phototherapy be used to treat atopic dermatitis (AD) as a second-line therapy, meaning that it is only used after the primary recommended treatment hasn’t worked to clear AD. In the treatment of AD, primary treatment is the use of emollients (moisturizers), topical steroids, and topical calcineurin inhibitors. Phototherapy may also be used as a maintenance therapy for people with chronic AD.1

Exposure to sun

When skin is exposed to sunlight, the body naturally produces vitamin D. Researchers have been studying the connection between vitamin D and the development of AD. While the exact cause of AD remains unknown, experts know there are several genetic and environmental factors involved. One of those environmental factors may be vitamin D. Some studies have shown lower levels of vitamin D are related to more severe AD. However, others studies have found high dietary intake of vitamin D may increase a person’s risk of developing AD. Additional research is needed to fully understand the role of vitamin D and AD.3

Practicing healthy sun behavior

Sunlight also has known risks, namely, increasing the risk of skin cancer. Skin cancer is the most commonly diagnosed cancer in the United States.

The National Eczema Association recommends practicing safe sun exposure practices, including:

  • Limit exposure to the sun between 10 a.m. and 4 p.m. The sun’s rays and exposure to UV light is strongest during this middle portion of the day, even on an overcast day. People should seek shade as much as possible. Young children (under 6 months of age) should be kept away from direct sunlight at any time of the day.
  • Wear protective clothing. If sun exposure is unavoidable, cover your skin with a wide-brimmed hat, long sleeves, and pants. Sun-protective clothing is also available that blocks out dangerous UV rays, and sunglasses can protect your eyes from damage.
  •  Apply sunscreen. Sunscreens provide a layer of protection against sun damage. Sunscreens can contain chemical UV blockers or physical UV blockers; chemical blockers absorb UV rays while physical blockers reflect them.4

Choosing a sunscreen

Some sunscreens contain chemicals that may irritate the skin of people with AD. AD causes damage in the skin’s natural barrier, which can make it more sensitive to irritating substances. Dermatologists frequently recommend physical blocker sunscreens, such as zinc oxide and titanium dioxide, which sit on the surface of the skin and are not absorbed into it. People with AD should also look for sunscreens that are hypoallergenic and that provide broad-spectrum protection, which protects against both UVA and UVB radiation.4 A sunscreen with SPF 30 or higher is usually recommended.

Emily Downward | June 2017
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