Does Sun Exposure Help Eczema?

Though too much sun can make atopic dermatitis (eczema) worse, some research suggests that moderate sun exposure can alleviate symptoms by triggering the release of compounds that helps dampen inflammation and neutralize harmful bacteria, fungi, or viruses on the skin.

This means that, with the right ultraviolet (UV) protection, you may be able to boost the effectiveness of your eczema treatments by stepping outdoors and taking in a healthy dose of sunlight every couple of days.

Eczema and Vitamin D

Although it is not entirely clear why sunlight helps relieve atopic dermatitis, some scientists believe that vitamin D plays a central role. Sun exposure increases the production of vitamin D in the skin and, by doing so, helps modulate immune function in the outermost layer of skin (called the epidermis).

Key to this is cathelicidin, which helps trigger the body's innate immune response. By increasing vitamin D production, sunlight indirectly increases the production of this amino acid compound.

People with eczema characteristically have low concentrations of cathelicidin in the skin; this confers to an increased risk of bacterial, viral, or fungal colonization. Even if these microorganisms do not cause an infection, their increased presence can lead to a worsening of eczema symptoms.

This may help explain, in part, why people with atopic dermatitis often get better with moderate sun exposure. Vitamin D supplements may further enhance this effect if there is a nutritional deficiency, although the evidence of this remains unclear and subject to controversy.

A 2017 study from McGill University found that low vitamin D levels do not lead to an increased risk of eczema or increase the production of immunoglobulin E (IgE) that spur inflammation. Further research is needed to make sense of these contradictions.

Eczema and Inflammation

Besides vitamin D production, sunlight may have other positive effects. Research has shown that exposure to UV radiation from the sun may help reduce skin inflammation, thereby alleviating some of the dryness, itching, and rash that characterize eczema.

A 2017 study published in the Journal of Allergy and Clinical Immunology found that exposure UV light causes the release of nitric oxide into the bloodstream. Nitric oxide triggers an anti-inflammatory response by activating a cell known as a regulatory T-cell (Treg).

As per their name, regulatory T-cells regulate the immune response and help "put the brakes" on an overactive immune system. Because eczema is believed to be caused at least in part by an exaggerated immune response, it is theorized that activation of Tregs may help reduce symptoms.

Sunlight and Eczema Prevention

Other scientists also believe that a lack of sunlight may contribute to the rise in inflammatory skin conditions. The hypothesis suggests that, as modern society moves to a more indoor lifestyle, the lack of sunlight alters the skin's barrier function and dulls the body's natural inflammatory response.

From an epidemiological standpoint, researchers are already seeing evidence of this.

Clinical evidence supports the hypothesis. A 2019 study from the University of Western Australia found that there was no difference in eczema between infants who were given vitamin D supplements compared to those who received none. What was discovered, however, was that the infants who received less UV light exposure were more likely to have eczema.

This would suggest that UV exposure may play an important role in the prevention of eczema by promoting a healthy, rather than excessive, inflammatory response.

Sunlight vs. Phototherapy

Ultraviolet light treatments (also called phototherapy or UV light therapy) has been utilized as an adjunctive treatment for eczema for many years. It works by utilizing a device that exposes the skin to controlled bursts of UVB or UVA rays.

Phototherapy works similarly to natural sunlight but in a more controlled way. Because of this, dermatologists can maximize the response by selecting the specific bands of UV radiation and filtering out those that cause the most harm.

The procedure can be done at your healthcare provider's office and is typically recommended when the first-line treatments of eczema (including topical steroids and immunomodulators) fail to provide relief.

Exposure Time and Risks

The "ideal" exposure time will depend largely on how sensitive your skin is to sunlight. Generally speaking, natural sunlight is considered safe for people with eczema when exposure is limited to 10 to 30 minutes of sunlight several times per week. People with darker skin may need more to see any relief of eczema symptoms.

Consequences of excessive sun exposure include:

• Sunburn
• Premature skin aging
• Uneven skin tone
• Hyperpigmentation (including melasma)
• Solar lentigines ("liver spots")
• Xerosis (abnormally dry skin)
• Actinic keratosis (a form of precancer)
• Skin cancer

Speak with your dermatologist to determine how much sun you can take per day and if there are any conditions you have (or medications you take) that limit the amount of sun you can reasonably handle.

Sun Safety Tips

Be aware that sunlight won't help everyone. In fact, for some, sun exposure can make eczema worse. Heat and sweat are common eczema triggers, making sun therapy a poor choice if your eczema tends to flare when you are overheated or during summer months.

While moderate exposure to natural sunlight may have benefits for others, safe exposure is key. If your healthcare provider gives you the OK to try this, there are a few tips you should follow if living with eczema:

• Start by limiting your daily exposure: When first starting, limit yourself to five minutes of exposure and see how your skin reacts. If there is redness or itching after a few minutes, you'll probably want to cut back. If there is no redness, tightness, or tingling, you can gradually increase the exposure over the course of days or weeks.
• Avoid the sun between 11:00 a.m. and 3:00 p.m.: This is when the sun is strongest and most likely to cause sunburn. Remember, the aim of the therapy is to alleviate eczema symptoms, not bronze your skin.
• Use sunscreen: A high SPF sunscreen works by filtering out UV radiation. UVA radiation is associated with skin aging, while UVB is associated with sunburns. Using a sunscreen with an SPF rating of 30 or higher allows for ample sun exposure while limiting damage to your skin.
• Avoid tanning salons: Tanning beds and booths utilize high doses of UVA radiation that tans the skin quickly but increases the risk of eczema exacerbations (as well as skin cancer and premature aging).

A Word From Verywell

Sun exposure is just one of the many options one can pursue in the treatment of eczema. Always speak with your healthcare provider about any complementary therapy you decide to pursue. While you may assume that "natural" means "safe," it's not always the case. This is especially true if your eczema is severe or you are being treated with multiple drugs.