Does Sun Exposure Help Eczema?

Hand reaching for sun.

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Atopic dermatitis, most commonly referred to as eczema, is a common, chronic, inflammatory skin condition in infants and children, and also affects about 1 to 3 percent of all adults. The causes of eczema are complex, but generally entail two factors:

  • A dysregulated immune system
  • Deficiencies in a person's skin barrier

In addition to the itchy, red, and inflamed skin rash of atopic dermatitis, people with eczema are also more likely to develop skin infections, especially with the bacteria Staphylococcus aureus.

To make matters worse, colonization of these bacteria on the skin in people with eczema (when the bacteria live on the skin, but do not invade it) tends to worsen their disease, creating a vicious cycle of inflamed, itchy skin that becomes infected and then more inflamed. This is why doctors focus not only on treating a person's inflamed, irritated skin in atopic dermatitis, but also on preventing and treating skin infection.

The good news is that one type of treatment that may help combat both skin inflammation and infection is judicious exposure to sunlight.

Benefits of Sunlight

It's not completely clear why sun exposure helps atopic dermatitis, but one study suggests that vitamin D may play a role as sun exposure increases vitamin D production in the skin. More specifically, supplementation with oral vitamin D appears to increase the production of cathelicidin in the skin of people with atopic dermatitis.

Cathelicidin is a protein that protects against skin infections from viruses, bacteria, and fungi in healthy skin, and people with atopic dermatitis have low amounts of cathelicidin in their skin. These lower levels may result in colonization and infection of the skin with bacteria, viruses, and fungi, which is known to worsen eczema in people with atopic dermatitis.

The increased production of cathelicidin may explain why people with atopic dermatitis often get better with moderate amounts of sun exposure. Vitamin D supplementation may further enhance the effect, particularly if you are nutritionally deficient.

Always check with your doctor before taking any vitamin D supplement. Doses higher than the recommended 600 IUs per day should only be taken under the care of a doctor. Overdosing can lead to nausea, vomiting, bone pain, and kidney problems.

Similarly, while cautious amounts of exposure to natural sunlight may be very healthy, tanning salons should be avoided, as too much sun exposure puts a person at risk for skin cancer and premature aging. Furthermore, people with atopic dermatitis may be more prone to sunburn, especially when they are using topical steroids or Elidel/Protopic.

Diagnosing Vitamin D Deficiency

It is always wise to speak with your dermatologist before embarking on sun exposure therapy. If you do, your doctor recommends a vitamin D blood test, first, to ensure that you are indeed deficient.

The most accurate way to measure vitamin D is with the 25-hydroxy vitamin D blood test. Normal vitamin D levels are between 20 nanograms per milliliter (ng/mL) to 50 ng/mL. Anything less than 12 ng/mL indicates vitamin D deficiency.

Certain people are more prone to vitamin D deficiency than others and may inherently benefit from supplementation. Factors for deficiency include:

  • Obesity
  • Living in northern latitudes with low levels of sunlight
  • Having dark skin which decreases the natural production of vitamin D
  • Poor absorption of vitamin D in the intestines (such as happens with celiac disease)

While vitamin D deficiency often causes no symptoms, people who are deficient will often complain of fatigue, muscle weakness, and muscle pain. Over time, severe deficiencies can lead to brittle bones and the increased risk of fractures and osteoporosis.

Other Eczema Treatments

It's important to note that sensible sunlight exposure or vitamin D supplementation (if recommended) is simply one part of a person's eczema treatment regimen. This is because eczema care requires a holistic approach—a combination of therapies, so to speak.

With that, other eczema therapies you should discuss with your or your child's dermatologist include:

  • Behavioral modifications (for example, limiting bath time to five to ten minutes)
  • Avoiding known triggers like food allergens or very dry, hot environments
  • Good skin care (for example, applying a thick cream or ointment-based moisturizer like petroleum jelly at least twice daily)
  • Controlling itching by cutting fingernails short or taking an antihistamine
  • Considering eczema medication like topical steroids

A Word From Verywell

Vitamin D deficiency is a hot topic these days and has been linked to a number of other health conditions like multiple sclerosis, heart disease, diabetes mellitus, infectious diseases, and cancer. Even so, the research on its role is still being teased out, so be sure to communicate with your doctor about whether a Vitamin D supplement is reasonable for you.

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Article Sources

  • American Academy of Dermatology. (2017). Atopic dermatitis.
  • Hata TR, et al. Administration of Oral Vitamin D Induces Cathelicidin Production in Atopic Individuals. J Allergy Clin Immunol. 2008; 122:829-31.
  • Quirk SK, Rainwater E, Shure AK, Agrawal DK. Vitamin D in atopic dermatitis, chronic urticaria and allergic contact dermatitis. Expert Rev Clin Immunol. 2016 Aug;12(8):839-47.
  • Scaria S, James E, Dharmaratnam AD. Epidemiology and treatment pattern of atopic dermatitis in patients attending a tertiary care teaching hospital. Int J Res Pharm Sci.2011;2(11):38–44.